Elisabeth C. Miller Library

Gardening Answers Knowledgebase

Search Results for: Pruning | Search the catalog for: Pruning

Recommended Websites

Plant Amnesty

Information Resources for Pruning and Tree Care

More websites

Plant Answer Line Question

Keywords: Pruning, Clematis

There is a very large evergreen clematis starting to devour my detached garage. How far back can I cut this and when should I prune it back? It's one of the first early spring bloomers with white flowers, possibly armandii? But I am uncertain...I need help since I don't want to butcher it and lose it, but it needs a big haircut!


Clematis armandii does have the reputation for taking over the world. According to the American Horticultural Society's Practical Guide on clematis (Clematis, by Charles Chesshire, 1999), you can prune it AFTER is has finished flowering, which in Seattle, it normally does by the end of March. While this type of clematis can be pruned in late winter, it flowers on the previous year's wood, so pruning at that time may remove buds and prevent flowering that spring.

Step 1 - remove any dead, dying, damaged, or deranged shoots.
Step 2 - they suggest that no real pruning is necessary but you can cut it back to control its growth. But you do NOT want to cut it all the way back into old dark, woody growth. Prune directly above a pair of strong side shoots.
Step 3 - you will need to keep after it each year to avoid a build up of tangled growth.

Fine Gardening has an article by Lee Reich on pruning clematis here.

Date 2020-03-28
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Pruning, Perennials--Care and maintenance

What causes my chrysanthemums to do the big flop? One even came out of the ground! We have had a lot of rain lately, and it seems like a lot of plants did the big floppy, from roses to sedum, and now the mums. Is it all weather-related?


Yes, certainly the weather contributes to the big flop. Certain perennials just can't stand up to heavy mist and rain.

Some gardeners stake their flop-prone plants before they flop over, while others dig them up and grow things that don't flop.

You can prune perennials to help prevent flop. Typically you cut a perennial back by 1/3 a few months before it flowers. This causes the plant to branch out, producing a bushier, shorter, less floppy plant. In The Well-Tended Perennial Garden (Tracy DiSabato-Aust, 1998), the author suggests that staking be done early: ...after the first flush of growth but before full growth. The stems need to be sturdy, and flower buds should not be formed yet...[stake] without adulterating the normal habit of the plants. Follow the natural line of the stem. (p.63)

Date 2019-11-07
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Abelia, Pruning

I recently bought an Abelia 'Edward Goucher.' When I got it home, I noticed a lot of the stem tips were broken off. I figured it probably happened when the salesperson pulled it away from the other plants. I tried to be very careful when I planted it, but again, some of the tips bent and broke. Then after a rainstorm the other day, I found a couple more broken. I love the plant, but is it going to be that fragile? I planted it on the southwest side of my house. Will the stems grow more sturdy?

Also, what is the best way to prune it? I thought I read that you shouldn't just trim branches but rather take some back to the ground. So if branches keep breaking, what will happen?


Woody shrubs purchased in nurseries often have the damage you describe, mainly from being packed into a truck for transport from the grower. Abelias are not particularly fragile when established - the branches thicken up and get stronger with time. You are right about not trimming (shearing) branches but cutting them to the ground or to a strong main branch.

The best guide to pruning abelias that I found is in Cass Turnbull's Guide to Pruning (Cass Turnbull, 2004, Sasquatch Books). She recommends removing whole branches if they are dead or damaged. When the plant is older, she suggests removing some of the lower branches that grow along the ground, and some of the taller branches that grow straight upwards. As mentioned, prune them back to a main stem. You can remove up to a quarter of the branches at a time. Pruning is best done in the winter months; pruning an abelia during the growing season will encourage it to grow even more. (In your situation, though, you might want to do some pruning during the growing season to encourage this sort of quick growth.)

Of course, if all your branches are broken, you will have to wait a year before you can do this kind of pruning - don't cut them all off. Old, overgrown plants can be cut to the ground for renewal, but a new plant probably will not survive this.

Finally, remember that this variety grows to 5 feet. Trying to keep it smaller by shearing it will lead to growth of water sprouts, and even more pruning...Cass explains all of this very well.

Date 2019-05-09
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Vitis, Pruning

I have a grapevine that is totally out of control and growing from the arbor into the trees. How and when should it be pruned back? I cut one vine that was up in the tree and it seemed to "bleed water."


From the American Horticultural Society Pruning and Training Manual, ed. by C. Brickell (1996, p. 289.):
"Prune only in midwinter when the risk of sap bleeding from cuts is at a minimum; any later, and bleeding may be difficult to stop (cauterization with a red-hot poker is the traditional remedy)."

From the book The Grape Grower, by L. Rombough (2002, p. 44-45.):
"Pruning Neglected or Overgrown Vines...If the trunk of the vine is straight, or is otherwise healthy, you may be able to short-cut the process by cutting everything back to the head of the trunk. You will have no crop that season, but you can easily train the new shoots that emerge as canes or new cordons to bear a full crop the following year.
More often, the vine will be such a mess of old growth and oversized wood combined with twisted, multiple trunks that the simplest way to prune it is with one quick cut, through the base of the trunk(s), right at ground level.
Kill the vine? No! Almost without fail, the vine will bounce back and refill the arbor or trellis in one season, because it has the full vigor of a large, established root system behind the new growth. The newly regrown vine should resume full production the very next year."

Date 2019-10-11
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Crocosmia, Pruning

Can Crocosmia be pruned or cut way down? When? The tall leaves are looking ungainly.


According to The Plant Care Manual by Stefan Buczacki (Crown, 1993), you should cut back the foliage as it discolors.

According to the Royal Horticultural Society, perennials that produce leaves and flower stems from below the soil level, such as crocosmia and peony, are cut back to soil level.

Date 2019-05-15
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Rosa, Pruning

I would like to know when is the best time of year to prune back (heavily) the roses in my garden. I have read that winter is best, when they are dormant, but I have also read spring is the right time.
Also, with roses that are possibly 20 years old or more, and have very woody stems, is it all right to prune them back to the woody (brown parts)? Or should I not cut back past the green parts?


In the Pacific Northwest, most sources recommend pruning in late fall or early spring. Where to cut depends on the type of roses you have (modern, climbers, shrub, etc.).

The Seattle Rose Society also provides excellent pruning information.

You don't mention what type(s) of roses you are hoping to prune, but the June/July 2011 Organic Gardening article by E.J. Hook, former gardener at the Woodland Park Rose Garden, covers basic pruning techniques for the 5 main types of rose.

Date 2019-10-02
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Pruning, Clematis

We are tearing out an old wood fence and replacing it with a new cedar fence, 6 feet high. We have a mature Clematis montana rubens growing on the old fence, prolific in growth and bloom, that I would very much like to save. Can I save it? We will have to start taking the old fence down right away. The new one is being installed next week, so I cannot wait until fall, which would probably be a better time to cut it back. Where do I begin pruning? Where do I stop? Anything I can do to lessen the shock to the plant?


Clematis montana is in pruning group 1 (or A) which means they do not take well to hard pruning. However, if it is the only way to save your Clematis, it is worth a try.

This is what the British Clematis Society recommends:
Category 1 (or A): No pruning.
"This category includes: C. montana If you wish to prune these types because they have outgrown their space they should be pruned immediately after flowering. You may or may not lose your plant as a result of the pruning. You might want to reduce the plant size over two or three seasons rather than in one go.
How-to: Start at the bottom of the plant and work your way up the stem to the first pair of plump, healthy buds. Prune the stem above the buds and remove everything above the cut. Treat each stem in a similar way."

Pruning is safer than transplanting:
"If a Clematis is to be replanted from an existing site, the late winter before bud break is the time to do this. However, it is only the large-flowered cultivars that generally can be replanted from an open ground position due to their large fleshy roots. The Clematis species and their cultivated forms have a very fibrous root system that usually breaks up when it is being dug up. The montana types are extremely difficult to replant once they have been established for more than two or three years."
Source: The Gardener's Guide to Growing Clematis, by R. Evison, 1998, p. 39).

Date 2019-11-07
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Sambucus, Pruning

I have two different elderberries that I would like to prune.
1. The first is a 'Sutherland Gold' (a cultivar of Sambucus racemosa) that is 5 years old, and I have never pruned it.
2. The second is a 'Black Beauty' (a cultivar of Sambucus nigra) that I just bought last year.
When should I prune? At what point on the stems? How far from the ground?


I consulted Peter McHoy's Practical Guide to Pruning, (Abbeville Press, 1993), and he recommends cutting one stem in three in mid-spring on plants that have been established for three or more years. You would cut to just above the ground level, choosing to prune out the oldest and weakest shoots first. Continue with cutting out shoots that will open up the center of the plant or improve its shape. It may look sparse afterwards, but new shoots will grow and fill in the space.

If you are growing the plants mainly for their foliage, he suggests cutting all the shoots back to 1-2 inches from the framework of the old wood in mid-spring.

Below is some more detailed information from the website of the Ontario Ministry for Agriculture, Food and Rural Affairs, which assumes you are growing the plants for their fruit production.
"During the first two seasons plants should be encouraged to grow vigorously with little to no pruning required. After the second year, pruning should be done annually in early spring. All dead, broken and weak canes should be removed. Three-year-old canes should be removed as they produce less fruit and appear to be more prone to winter injury. Removal of older canes will encourage the growth of new, more fruitful canes.
"Mowing of all the canes in a mature planting may be a method of reducing labour costs while encouraging growth of new canes. The disadvantage of this system is that there is a loss of production in the season following mowing as there is limited production on the one-year-old canes."

Date 2019-11-07
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Pruning, Fuchsia

I have several hardy Fuchsias that are quite large, about 4 - 5 feet tall, that bloomed profusely this year. The leaves are gone now, but when should I prune them? How far back should I prune? Is there anything special I need to know about pruning Fuchsias?


Fuchsias are pretty tough shrubs, especially once established. You can prune just to tidy them up, but it is best to wait until the leaves begin to grow (between March and June).

Here are two links to more detailed information:

From Rainy Side Gardeners, "Some years when we have an exceptionally cold winter, Fuchsias will die down to the ground. Before pruning in spring, wait until leaf buds swell, then prune out dead twigs, or prune down to the ground if winter knocked it completely back."

Another site is the Hardy Fuchsia List from the Northwest Fuchsia Society.

Date 2019-11-14
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Topiary work, Pruning, Hibiscus

I have a small hibiscus that I would like to train into a tree with the twisted trunk and I have no idea how to go about that. Please advise.


When you prune your hibiscus into a tree-like form with a single trunk, it is called a standard. There are even braided topiary forms. To achieve the twisted shape, you will probably need to create a support or frame.

The following general information on pruning comes from Tropical Hibiscus:

"While the tropical hibiscus can be pruned any time, probably the ideal is the earliest where the resulting tender new growth will be safe from cold damage*. For shaping purposes, some growers will prune the longest third of the branches and return in 4 to 6 weeks and prune the next longest third. Only sharp, clean shears should be used. A clean cut should be just above and angled down and away from an 'eye' or node. (A node is the junction of a leaf and the stem. There is a small bud in this junction that is activated after pruning.) Cutting above outward pointing "eyes" will encourage growth in that direction. The new growth resulting from pruning invigorates the plant and will provide a source for many new blooms."

The American Horticultural Society's Pruning & Training (edited by Christopher Brickell and David Joyce, DK Publishing, 2011) describes the technique for creating a braided stem:
"Form a braided stem simply by braiding together three flexible young shoots. Select the strongest three on a multistemmed young plant, and remove the remainder. Single-stemmed plants can be cut back hard to produce multiple stems."
The book also describes what is called a "barleysugar stem," which may be more like the twist or spiral you envision: in this technique, "use a sturdy wooden pole with dowel pegs inserted in a spiral along its length. Train one or two stems around the pole, holding them in place by looping them beneath the dowels. Remove the pegs and the pole in sections when stem growth has hardened."

Here is a link to Brooklyn Botanic Garden's article on espalier forms, Special Cases: Pruning for Particular Purposes.

The Miller Library has a good selection of books on pruning and training, and specifically on topiary. You can search the library's catalog by clicking this link.

Date 2020-01-31
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Wisteria, Pruning

Is it all right to cut off the hanging pods from the Japanese Wisteria? Will cutting them have any adverse affects to blooming next year? Some are hanging so long that we keep walking into them! Maybe I should cut them and bring them inside for decoration.


Cutting off the seedpods on your Wisteria is not a problem, just be careful not to cut the stems back too far (unless you are intending to prune, which you can certainly do if you need to control growth) as there may be buds further up which will be next spring's flowers.

Fine Gardening online has a helpful illustrated article on wisteria pruning which includes the following:
"Some seedpods may be left on the vine for winter interest, but just know that if you bring them inside, warm temperatures will cause them to explode."

You may find the following links to general information on care and pruning of Wisteria helpful:

  • Wisteria care: Get out your clippers twice a year and go to town from OSU Extension
  • Growing Wisteria from Ohio State University Extension
  • Excerpt from an article, "Pruning Vines," by Donald Hodel and Dennis Pittenger:

    Pruning wisteria extensively during the dormant season may encourage rampant vegetative growth the next spring. Instead, in July prune out the long, straggly growth except those branches needed for climbing. This is more likely than anything else to induce flowering. Shoots should be cut back one-third to one-half their length. This will induce them to produce the short spurs that will bear next season's flower clusters.

    Date 2019-05-09
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Polystichum munitum, Pruning

    We leave for about 5 months in the winter and by the time we get back our sword ferns have sprouted and it's hard to prune the old fronds out without cutting off the new ones. These ferns are in a fairly protected area, so I was wondering if it would be okay to cut off the old fronds in October before we leave? Also would it help if we just cut the old fronds and lay them over the plant to help protect it over the winter?


    There are some slight differences of opinion on cutting back sword ferns. It might be fine to cut the old fronds this fall and leave them as protection over the winter, but it isn't really necessary to cut them back until early spring, if at all. The local web site for Great Plant Picks recommends cutting sword ferns to the ground in late winter, or only cutting back every 3 years or so on plants growing in poor soil:

    Paghat's Garden, another local gardening site recommends only cutting away dead fronds. Excerpt:

    It was once believed it was necessary to cut all the fronds off in February immediately before new growth begins, but it is now the recommendation to only trim dead fronds. By April when the fiddleheads are thickly erupting, any of last year's fronds that have lost their beauty should be removed, but only for looks' sake, removing up to as many as all of them. They'll soon enough be replaced by new. Just don't remove the fronds before winter's final frosts, as the reason this fern adapted itself to keeping its fronds green at least until winters' end is to shelter & protect the humping crown from excessive cold or from sunlight in winter when deciduous trees might not adequately shade the rootcrown.

    Since your plants are in a protected area, you might be able to go ahead with your October trimming, but really the main reason to trim is an aesthetic one, so it isn't absolutely necessary.

    Date 2019-05-17
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Aceraceae (Maple family), Pruning

    I live in Wausau, Wisconsin. Our city planted small maples two years ago near the street. They are now about 8-10 feet tall. Both of ours show some encircling roots above the surface of the ground under the mulch. The roots are about 1/2 inch diameter in one case and a bit larger in the other. Is it too late to prune these away? Any other suggestions?


    The answer to your question will depend, to some extent, on the type of maple tree you are growing. Silver maple will tolerate root-pruning, but sugar maples are intolerant of it, and can be more likely to break in windstorms if roots are pruned. There is always some risk of loss involved in root-pruning a tree. Source: Iowa State Extension.

    Since encircling roots are not good for the tree, you probably will need to prune, but it would be best to consult a certified arborist in your area to make sure this is done correctly. University of Minnesota has a guide called "Stem Girdling Roots: The Undergound Epidemic Killing Our Trees" by Gary Johnson. Excerpt:

    Removal is the most common treatment of encircling roots or SGRs that have caused minimal stem compression. Roots may be removed with wood gouges, saws, or pruners during the examination process.

    When SGRs have caused extensive stem compression and are fully or partially embedded in the stem, modify the removal treatment to avoid damage to the stem. Embedded and severely compressing SGRs are often left in place when they cannot be safely removed; there is some belief that SGRs reduce the typically short life span of urban trees by only a few years, and the potential damage associated with SGR removal is not justified (Watson et al. 1990; Tate 1981). A compromise is to prevent the SGR from growing and further compressing stem tissues by severing it at the edges of the stem. Remove the remaining root to a distance where it no longer poses a threat to the stem and allow the severed SGR to decay with time. Annual examination of the stem to assess for decay is recommended.

    The season during which SGRs are removed might influence the success of the treatment. Smiley (1999a) found that summer removal resulted in better diameter growth over two years than did fall removal or a combination of summer and fall removal for red maple trees under an irrigation system.

    Regardless of treatment, do not backfill the examination area. Lightly mulch the exposed roots but not the root collar flare or stem area. Subsequent examinations will not require the time-consuming removal of soil.

    To find a certified arborist in your area, you can search your local chapter of the International Society of Arboriculture.

    Date 2019-05-18
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Woody plant propagation, Brugmansia, Pruning

    When should I cut back angel's trumpet and can I replant the part that was cut?


    I've checked a book called Brugmansia and Datura: Angel's Trumpets and Thorn Apples by Ulrike and Hans-Georg Preissel. It has a whole chapter on growing angel's trumpets from cuttings as well as a section on pruning them, which should be done after they bloom. As you probably know, they can't take freezing temperatures, so people often prune them in the fall to make them easier to bring into a greenhouse (for overwintering warm) or 41-50 degree room (for overwintering cool). The important thing to remember is to confine your pruning to the flowering part of the plant, so you don't have to wait as long for more flowers. The book says you can tell the flowering part of the plant by looking closely at the leaves--the flowering part has an asymmetrical leaf base on each leaf, but the base of the "vegetative" leaves is symmetrical.

    The cuttings you take can be used to start new plants, and the success rate will vary depending on the time of year (spring and summer cuttings work best) and the variety of angel's trumpet you have. Viruses can be a problem, so keep your shears very clean. You can often get them to form roots by placing them in a jar of water so that only the lowest 1.5 inches of the stalk are under water. Alternatively, place woody fall cuttings "about 10 inches long...in a mixture of peat and sand, in vermiculite, or in pumice... temperature between 53 and 64 degrees... Many of these cuttings will form roots by the following spring. For root development the cuttings need the same light levels as for good growing conditions... It is a good idea to pot all cuttings into a nutrient-rich soil as soon as possible after they have formed roots."

    Date 2019-05-23
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Wisteria, Pruning

    I have a wisteria that has gone untamed for a few years, and I need to know when and how to go about pruning it back to a reasonable size. It grows up the fence to a pergola-like structure, but it's gone way past that to begin attaching itself to surrounding trees.


    Local pruning expert Cass Turnbull of Plant Amnesty has written about pruning wisteria. Here is a link to the article on Plant Amnesty's website. The relevant passage (about renovating an out-of-control vine) is excerpted below:

    RENOVATION. If it gets away from you or you have moved into a home that already has an enormous wisteria tangle, grabbing and strangling everything in sight, show no mercy. Lop, saw and chain saw whatever is necessary to get it back down. I suggest you cut several feet below where you want the regrown vine to be, since you will experience an upsurge of new shoots the following spring. As with all heading cuts, the new growth occurs directly beneath the cut and heads up from there. You will need some room to let it regrow over the next few years. New growth will be vegetative (not flowering) and rampant for a few years. I wouldn't be surprised if some major stems die back partially or totally, if you make cuts one inch or over. But I doubt that you will kill the plant. As some stems die back, cut off the dead bits. Others will supply the replacement shoots to be tamed in upcoming years.

    Local gardener Ciscoe Morris also has information about maintaining wisteria vines. Excerpt:

    To prevent damage to your house and to encourage flowering, prune the tendrils to about 4 inches from the main structural vines when they grow beyond a foot long. This is a form of spur pruning. It encourages flower buds to form by concentrating all of the energy that would have been used to grow the long tendril into a 4-inch stub. While you are at it, you may as well construct a shed under the wisteria to store your ladder, because within only a few weeks, new tendrils will begin to grow and you'll be climbing up to do it all again.

    The Royal Horticultural Society also has information on pruning and training wisteria in an article entitled Pruning and Training Wisteria.

    According to the American Horticultural Society's Pruning & Training (edited by Christopher Brickell; DK Publishing, 1996), the times to prune are midwinter and again in summer, about 2 months after flowering. With an established wisteria, the goal of regular pruning is "to control extension growth and to encourage the production of lateral flowering spurs. The current season's shoots are cut back in two stages to within two or three buds of their base. These will bear the coming season's flowers. Growth and flower buds are easily distinguished in late winter, the former being narrow and pointed, the latter plump and blunt."

    Date 2019-10-30
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Juniperus, Pruning

    I have a young 5-foot tall Hollywood juniper. How do I prune it to shape and train it so it looks good?


    Because of the natural beauty of its form, Hollywood juniper, or Juniperus chinensis 'Torulosa', is not a good candidate for pruning, and I would recommend only pruning branches which are interfering in some way, such as intruding into a walkway. Below are links to information on pruning junipers:
    University of Georgia Extension
    "Junipers do not tolerate heavy pruning because of the lack of new growth on old wood. This makes it important to know the growth habit of a particular juniper prior to planting so that future pruning can be minimized. Junipers can be tip pruned and thinned, but not cut back to large limbs. Pruning out old. dead foliage underneath creeping junipers will often contribute to better air circulation and thus better health of the plant."
    University of Florida Extension
    Excerpt: "Torulosa Juniper develops into a showcase specimen without pruning and is probably best used for this purpose."

    In her Guide to Pruning (Sasquatch Books, 2006), local pruning expert Cass Turnbull advises strongly against shearing and cutting into old wood, because you will be looking at woody stubs for a long time, if not forever. You can remove lower limbs which may be blocking sidewalks, but in general, avoid pruning. "Junipers, like most conifers, are difficult to prune. This is because the barren portions of the branches can't produce new greenery (break bud) once the exterior green has been removed (headed back). Never expose those ugly, barren internal branches . . . What little can be done to help an overgrown planting involves removal of the lowest limbs, and/or selective heading (grab and snip) or thinning off the worst, most interfering branches. Always hide the cut beneath some natural-looking greenery."

    Your young plant should shape and train itself without the intervention of pruning.

    Date 2019-10-11
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Pruning, Phormium, Lavandula stoechas, Hebe, Effect of storms

    How should I prune winter-damaged Phormium, Hebe, and Spanish lavender? The Phormium leaves look wilted. They are folded over and discolored but not blackened. The Hebe 'Autumn Glory' and 'Great Orme' are blackened, while 'Shamrock Purple' is mostly brown. The Spanish lavender has some blackened foliage, but mainly just got weighed down with snow.


    My advice for right now would be only to prune any branches which were broken under the weight of the snow. We may yet have more cold weather, so you don't want to make your plants any more vulnerable.

    You may want to wait until early spring or at least all danger of further frost or snow and ice to prune your Spanish lavender (Lavandula stoechas). Under normal circumstances, Spanish lavender can be pruned back by a third to one half in early to mid-autumn, according to Lavender: The Grower's Guide by Virginia McNaughton (Timber Press, 2000). I grow Spanish lavender, and I usually tidy the plants a bit when most of the flowering is done. However, because of the extreme cold to which your plants were exposed, you may want to assess them in spring, and prune out any dead areas, or replace any mostly-dead plants.

    I recommend giving the Hebe plants a chance to recover. I have heard of very sad looking Hebes coming back, perhaps not the first summer, but by the following year. By mid- to late-spring, you should be able to tell what is truly dead and prune it, though Hebes sometimes dislike hard pruning. The Hebe Society of New Zealand suggests pruning frost-damaged shoots in spring.
    An article in the Kitsap Sun from May 2011 by Kitsap County Extension agent Peg Tillery mentions hard-pruning winter-damaged Hebes which manage to recover.
    You may find this information from Oregon State University useful, as it evaluates the cold hardiness of individual species of Hebe. Here is an excerpt:
    "Major cold damage will cause browning of most of the leaves on the canopy, followed by dieback. Sometimes, plants will recover over a 2-3 year period from this damage if subsequent winters are mild. Very severe, sudden cold often turns the entire plant brown and sensitive cultivars do not recover from this damage and require replacement."

    There is a discussion of winter-damaged Phormium in Houzz, an online gardening forum. Again, I suggest waiting until spring to see if only parts of the plant are dead. Keep in mind that gloves are essential when pruning this plant!

    The Oregonian has an article about the effects of the December 2008 cold and snow on tender plants. Here is an excerpt:
    "I hope, unlike me, you've had better luck with your phormiums surviving the storms. Not to be negative, but chances are you didn't. On the positive side, though, they'll most likely only die to the ground. If you cut them back, phormiums often come back from the roots."

    Date 2019-10-31
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Pruning, Hydrangea

    It's January, and my hydrangeas look terrible. When should I prune them?


    The answer will depend on which species of hydrangea you are growing. According to the American Horticultural Society Pruning & Training edited by Christopher Brickell (DK Publishing, 1996), Hydrangea macrophylla (big leaf or mophead hydrangea) should be pruned after flowering in warm climates but in colder climates it is best to leave the old flower heads on the plant over the winter, and prune in spring. This rule also applies to Hydrangea serrata. If your hydrangea is blue-flowered, it is probably H. macrophylla. In her Guide to Pruning (Sasquatch Books, 2006), local pruning expert Cass Turnbull of Plant Amnesty says this plant should not need much pruning, but if you want to remove the faded blooms, you can do this in February by looking for four or five pairs of plump buds below the old flowers, and cutting just above the lowest or second lowest set of buds.

    Hydrangea paniculata should be pruned in early spring, before active growth begins.
    Hydrangea arborescens needs little pruning, and any pruning at all should be done in early spring.
    Oakleaf hydrangea (Hydrangea quercifolia) also needs little pruning, but may be pruned in spring.

    >The U.S. National Arboretum offered a good introduction, no longer available on their website, but excerpted here:
    "Established bigleaf, panicle, oakleaf and smooth hydrangea plants can often benefit from regular pruning. Removing about one-third of the oldest stems each year will result in a fuller, healthier plant. This type of pruning is easiest to do in winter, since the absence of leaves makes it easier to see and reach inside plants.
    Gardeners may also want to prune to control height or to remove old flower heads. The best time for this type of pruning differs between species. Bigleaf and oakleaf hydrangea, which flower on previous year's growth, should be pruned shortly after flowering is complete. Panicle and smooth hydrangea flower on current year's growth and can be pruned anytime from late summer until early spring. If pruning these two species in the spring, try to prune before leaves appear. Plants of H. arborescens 'Annabelle' have been known to produce a second flush of flowers if pruned lightly after the first flowering.
    Stems of bigleaf hydrangea that have been damaged by cold should be pruned as soon as it is determined that they are dead. Watch for new growth at the base of the plant. If your plant has basal shoots that are 6 to 8 inches in length, but the upper parts of the stems are still bare, then the bare stems need to be removed. For bigleaf hydrangea plants that are subject to frequent weather-related dieback, other than removing the dead stems, you probably won't ever need to do any other pruning--Mother Nature has been doing the work for you."

    Kitsap County Master Gardener Peg Tillery, in an article formerly available on the WSU Extension Kitsap County web site, recommends waiting until March to prune hydrangeas: "In our climate we need to wait until early March to prune roses and summer blooming hydrangeas. This way the tender new growth won't be harmed by frosts."

    The Royal Horticultural Society provides general pruning recommendations.

    Here is an excerpt from a Seattle area gardener's response to a question about hydrangea pruning on Garden Banter, a British gardening forum:
    "Different species of hydrangeas have different criteria for pruning. Some need very little pruning at all,other than to shape, as with H. quercifolia and H. anomala petiolaris. H. arborescens does well with the dramatic pruning you describe. Pruning of H. paniculata would depend on if you were training it to be upright like a tree or as a broad shrub, and need not be dramatic pruning, just barely enough to induce new growth on which flowers occur, though in your zone a more dramatic pruning might be needed because of winter damage. Most hydrangeas prefer late winter pruning, but H. macrophylla is better done in late summer when flowers are getting scruffy and new shoots are developing."

    Date 2019-04-27
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Dryopteris, Pruning, Ferns

    My wood ferns (now about 4 feet in diameter)have fronds which are now partially brown. Can I prune all the 'old' fronds off and let the new ones take over without damaging the plant? When should I do this?


    Sources are divided on when and whether to prune wood ferns (Dryopteris). Some consider Dryopteris "self-cleaning," meaning that the old fronds will eventually disintegrate on their own (Gardening with Woodland Plants by Karan Junker; Timber Press, 2007). If you are inclined to tidy up the look of your plants, they can be pruned of their old fronds after new growth begins in the spring (be careful not to cut the new fronds), or according to other sources, in late February or early March before new growth starts. Rainyside Gardeners and Great Plant Picks, two Pacific Northwest resources, offer more information. Rainyside advocates pruning once there is new growth, and Great Plant Picks advocates pruning before new growth begins.

    Date 2019-08-02
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Campsis, Pruning

    I have a beautiful trumpet vine which grows against a south-facing fence. It flowered for the first time this year. Several sources say to prune it in March. Is that correct, and if so, how close to the ground should it be pruned? Also, I'd like to plant a few to climb my pergola. Should they be planted in the ground or would large pots be OK?


    Your sources are correct, although my research indicated that 'late winter to early spring' is fine for pruning Campsis radicans. Whenever you prune, you want to consider that frost (or even cold weather and/or wind) can damage new growth--March is generally considered a safe time from that perspective.

    Trumpet vine flowers on growth produced during the current season, so you can cut it back hard if you are trying to control its growth. Pruning it to within 6-8 inches of the ground (when it's young or if it needs a renovation later on) will encourage vigorous growth of a stout, strong set of basal branches.

    The American Horticultural Society's Pruning and Training (DK Publishing, 1996), says the following:

    • Select two or three of the strongest shoots and remove the rest.
    • Train [them] to the supporting wires or trellis (...) until shoots extend fully over the allotted space (...) it may take two or three seasons to complete the framework (...)
    • Once it is established, prune the plant annually, spur-pruning all lateral shoots back to within two or three buds of the main stems.

    If you prune it to the ground next year, you can begin to develop a strong framework, if you haven't already. Otherwise, you can prune as needed to the suggested two or three buds from the main stem. You can also follow this set of instructions if you choose to do a renovation. Over time, this vigorous plant may outgrow its space; you can then cut it to the ground and let it come back. It responds well to hard pruning.

    I did not see mention of this plant in any of several books I consulted about container gardening. While that does not mean you cannot grow this vine in a pot, my suspicion is that the stout base required of this vigorous grower may not develop in a pot. This plant does need sufficient room for a root system that can support the base and each season's growth. If possible, I think you should plant the vines in the ground.

    Date 2019-05-23
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Winter gardening, Pruning, Helleborus

    I am noticing that the flower bud shoots for my hellebores (Helleborus x hybridus), are starting to push up above the soil surface. There is still a substantial stand of foliage in good condition.

    My question is about pruning. I know I'll need to prune about half the leaves away (I understand that the cut should be made at the base) to give the flowers more visibility. Does it harm the plant to prune it during this cold snap? Does it harm the plant to cut ALL the old leaves off in December as the bud stalks begin to appear?

    I would appreciate any guidance you can give me, such as when and how extensively to prune them.


    According to Hellebores: a Comprehensive Guide by C. Colston Burrell and Judith Knott Tyler, "all the hybrids maintain their foliage (...) throughout all or part of the winter (...) In any case, as the flower buds begin to stir in the center of the rosettes, it's best to remove all the foliage to make way for the flowers. Nothing spoils the garden display like a tangle of flowers wrestling with winter-burned leaves. The juice is caustic and sometimes causes a rash, so take care when removing the old leaves."

    In The Gardener's Guide to Growing Hellebores, Graham Rice and Elizabeth Strangman advise a more time-intensive method:
    "The best approach is to cut off some leaves during the autumn and early winter when the garden is put to bed, concentrating on removing dead leaves and any showing signs of blackening (...) By Christmas time they should be thinned out sufficiently to leave a good circle. However, as our winters become windier it may be wise to remove them entirely at this stage. (...)Thin the leaves further as the flower stems emerge, then just before they are in full flower remove all the old leaves. (...) To compensate for the removal of the last of the leaves the plants deserve a good mulch." They go on to suggest compost or a mulch of leaves for this purpose. The cold snap is unlikely to harm even recently pruned hellebores, as they seem to thrive in the cold.

    Date 2020-09-23
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Pruning, Plant cuttings, Dracaena

    My indoor Dracaena is getting too tall. I'd like to prune it, and maybe use the cuttings to start new plants. How do I do this?


    You should be able to do both tasks. The Complete Houseplant Survival Manual by Barbara Pleasant (Storey, 2005) says "when plants become too tall, cut off the cane at any height. New leaf clusters will grow from just below where the cane was cut. You can cut sections into 6-inch pieces and root them like stem cuttings."

    You might also find this discussion from University of British Columbia Botanical Garden's online forum useful.

    Here is more information, from University of Florida, which describes how pruning will result in two or more branches forming where the pruning cut was made: "Cut one or two of the stems to a point where new foliage is needed."

    Date 2019-11-07
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Pieris, Pruning

    I have a Valley Rose Pieris which has finished blooming. I wanted to trim it, but noticed that it has small green buds on the branches. What would be a good time to trim this plant?


    The best time to prune Pieris is in the spring when it is done flowering. You can prune it to the shape you desire. It grows new shoots readily from old wood, according to Peter McHoy's Pruning: A Practical Guide (Abbeville Press, 1993). There are more detailed guidelines in Cass Turnbull's Guide to Pruning (Sasquatch, 2006). She says you can remove up to a quarter of live foliage without endangering the plant. Always remove dead, diseased, or awkward growth first. She recommends thinning out branches which are too straight, too skinny, or wander too far. Working from the inside of the shrub outward, your goal would be to make the growth less crowded. Pieris also responds to being "limbed up" and treated like a tree, with lower branches removed, if that is a shape you prefer.

    Date 2019-06-06
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Pruning, Malus domestica

    I have a five-variety dwarf apple tree that is doing well, but seems to be developing a very strong central leader. (I planted it last year.) Is this going to be a problem? I seem to remember hearing that I shouldn't let it do this, but I ca't find any information about how to prune this type of apple tree.


    As I suspected, the answer to your pruning question was lurking in the pamphlet I received many years ago with my Raintree Nursery tree order. Here is what they say about "combo fruit trees" and their care:
    "Combination fruit trees with several varieties on the same plant can be a fun way to grow lots of varieties in a limited area. They can be somewhat challenging too. Often one or more varieties (branches) will be much more vigorous than others. If this problem isn't carefully addressed, then the tree can become more and more lopsided and the most vigorous varieties will overgrow the others and dominate the tree. Prune back the most vigorous branches upon arrival (if we haven't already done so) to even out the branch lengths. Prune the most vigorous branches back again in the summer to maintain a balance. The most vigorous branches are the most upright. Spread the branches if they are supple enough to spread without breaking. If you keep any upright branches and they are too stiff to spread, cut them back, if possible to the lateral side branches. The combos should be grown as open center trees. On most combo trees, the varieties are named on the plastic label attached to the tree with the bottom budded variety listed first, the second from the bottom listed second and so on. Missing varieties are crossed out on the label."

    University of Minnesota Extension has information on open center pruning.

    Oregon State University Extension has a good general guide by Jeff Olsen to Training and Pruning the Home Orchard.

    Date 2019-06-12
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Arbutus unedo, Pruning

    I have an Arbutus unedo 'Compacta' planted in my garden, close to the property line. My neighbors want me to shear the top and sides so that they can see the view beyond it while seated on their sofa. I really don't want to do this, but I need to provide a convincing argument that shearing is not the best way to prune my Arbutus.


    It's difficult to imagine topping and shearing the compact form of Arbutus unedo which is unlikely to exceed 10 feet. Ideally, it would need no pruning whatsoever. Local pruning expert Cass Turnbull of Plant Amnesty classes Arbutus unedo with other "tree-likes," shrubs or small trees which should be maintained with a tree-like shape. Below are excerpts from her recommendations on pruning (and there is a brief guide on Five Reasons to Stop Topping as well):
    "DON'T: Ornamental trees should never, ever be topped. And shrubs should rarely be sheared (except real topiary and formal hedges). Stripping all of the side branches off of a mature pine or any other tree or shrub, is also a no-no. Stripping is not to be confused with selective thinning, which can also make shrubs and trees look open and Oriental.
    Best let to get big. Not to be pruned heavy-handedly. Good selective pruning can open them up and make them look less oppressive, can train branches around gutters and off of houses, and can bring more beauty out of your plant. These shrubs are the hardest to do. Never remove more than 1/8 total leaf surface in one year. It stresses them or it can cause a watersprout-rebound effect --- ick! Tree-likes have stiffish branches, generally. Examples of tree-likes include rhododendrons, andromeda (pieris), magnolias, deciduous Viburnums, camellias and witch hazel.
    Most tree-likes just need to have all of the dead wood taken out.
    If you still want to do more:
    Take out suckers (straight-up, skinny branches from the base and trunk of the shrub or tree.
    Take out any big crossing, rubbing branches and double leaders (two main top branches with a narrow branch-crotch angle) on trees.
    Take back or remove any branches hanging on the ground, if only up 1/2".
    Take out the worst of the smaller crossing, rubbing branches --- choosing the healthiest and best placed branch to remain.
    Prune to shorten or completely remove the worst wrong-way branches that start from the outside of the shrub, and go the wrong way back into the center and out the other side. Sometimes a side branch has a smaller branch that heads too far up into the next "layer", or goes too far down. You can cut some of these off to add more definition to your shrub's branches.
    If you have two parallel branches rather close together, it may look better to remove one. If you, have three parallel branches you may want to remove the center one. This will make things look nicer.
    Before you finish, stand back and observe. If necssary, you may sparingly shorten some branches on tree like shrubs (not trees). Cut back to a side branch."

    Another resource, Peter McHoy's A Practical Guide to Pruning (Abbeville Press, 1993), says that Arbutus unedo "can be trained with a single trunk, as a multi-stemmed tree, or left unpruned to form a dense shrub." He does not mention shearing it like a hedge. According to The American Horticultural Society's Pruning & Training edited by Christopher Brickell (DK Publishing, 1996), you can prune Arbutus unedo in spring, as soon as danger of frost is past (that would be early April in Seattle), but keep pruning to a minimum. Some people choose to remove lower branches to create a taller trunk on younger trees.

    Your neighbors may be under the misapprehension that shearing will control the size of the plant. In Cass Turnbull's Guide to Pruning (Sasquatch Books, 2006), the author says, "Because shearing is nonselective heading, it will stimulate bushy regrowth, creating a twiggy outer shell on sheared plants. This layer of twigs shades out the interior which then becomes leafless and full of dead leaves and deadwood. Meanwhile the outher shell becomes thicker and larger every year because, as it is sheared repeatedly, it must be cut a little farther out to retain its greenery. This dense, twiggy outer shell makes size reduction difficult because cutting back too far exposes that ugly dead zone inside the shrub. [...] Therefore, shearing is not a good way to control the size of a shrub. [...] Shearing is also a drain on the health of plants.[...] Shearing plants creates the antithesis of a healthy environment, making shrubs more prone to insect attack, deadwood and dieback. It adds a general stress on plants because the rapid, profuse regrowth promoted by repeated heading depletes their energy, and their resulting weakness and tender growth makes them more susceptible to injury from freeze or drought. [...] shearing often defeats the purpose of shrubbery, usually by cutting off the flowers, but other characteristics get subverted as well." If these are not reasons enough, it is not cost-effective to shear, as it must be done repeatedly."

    You may wish to contact Plant Amnesty to obtain a referral for a consulting arborist who will speak on your behalf.

    Date 2019-10-03
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Pruning, Effect of storms, Conifers

    There's a self-described tree service knocking on doors in my street, trying to get people to pay them to do "wind sail reduction" on their trees. My neighbor just agreed to have them prune 17 of her conifers. Bad idea, right? Can you point me toward resources so I can dissuade her from going ahead with this plan?


    Yes. The Washington Department of Natural Resources published an article, "Trees Don't Wind Sail, Do They?," in their online newsletter, Ear to the Ground, 12/20/2011. Here is an excerpt:
    "Some people claiming to be tree experts will tell you that 'wind sailing' is a great way to protect your trees from wind damage. You may have heard this fabricated notion of thinning limbs from trees in order to make them stable during wind storms. This improper pruning technique is promoted to supposedly make trees safer in the wind by allowing wind to pass through the canopy of a tree, thus reducing movement and strain on a tree. Not so!
    "This may sound reasonable and may even seem to have some logic behind it. But beware--the truth is, there is no scientific study that shows thinning is wise or safe way to decrease resistance during a wind storm. "Actually, many studies have shown that the outside limbs can divert some wind from the center of the tree and act as a buffering shield. Aggressive thinning, on the other hand, can make the remaining branches more vulnerable to failure; left isolated, these limbs must take on the elements alone. Pruning out a major portion of a tree's canopy for the sake of staying upright during a wind storm harms most trees in the long run."

    The DNR has another, similar article from 12/6/2012 in their Tree Link News entitled 'Windsail Reduction:' A Northwest Controversy.

    You can also suggest that your neighbor speak to someone at Plant Amnesty, a local organization dedicated to teaching the community about proper pruning techniques (as well as informing them about ill-advised methods!).

    Date 2019-12-27
    Link to this record only (permalink)

    Plant Answer Line Question

    Keywords: Rubus idaeus, Pruning

    It's late September and my raspberries are done producing fruit. The canes are really tall. How should I go about pruning them?


    According to Linda Gilkeson's Backyard Bounty: The Complete Guide to Year-Round Gardening in the Pacific Northwest (New Society Press, 2018), the simple method is to wait until the dormant season and cut down canes that bore fruit last year. (You can tell these canes by their rougher and darker grey bark, compared to the lighter and smoother canes of the last growing season.)

    This will work for summer-bearing as well as everbearing varieties, but some choose to prune everbearing (also called primocane-fruiting) raspberries in two stages. An everbearing raspberry is one that produces fruit in the early fall of the first year on their primocanes. It then fruits a second time, in June, on buds below those which fruited the previous fall. In the dormant season, prune off only the top part of the canes that have fruited, and let the remainder fruit next summer. Then you can prune out the whole spent cane the next winter. Try to keep only five to ten new canes per plant.

    This Oregon State University Extension guide to Growing Raspberries in Your Home Garden may also be helpful to you.

    Date 2019-09-19
    Link to this record only (permalink)

    Garden Tip

    Keywords: Juglans, Gleditsia, Prunus, Pruning, Cornus, Birch

    A common question gardeners have is when to prune. "When the shears are sharp!" is the often-heard answer. In reality there are a few timing guidelines that do matter.

    First of all, certain trees are known to "bleed" when pruned while the sap is rising in late winter and early spring. Maples, dogwoods, birch, elm, walnut and honey locust are the most common.
    Bleeding usually won't hurt the tree, but the pruning cuts are slower to heal which may leave susceptible trees vulnerable to infection. These trees should be pruned right after leaves fall off in autumn.

    Cherry trees are at risk from the destructive cherry bark tortrix. The tortrix is attracted to fresh pruning cuts, so cherry trees should not be pruned between May and August when the tortrix is active.

    Spring flowering shrubs should be pruned immediately after flowering so that the new growth has time to form next year's flower buds. Summer flowering shrubs may be pruned in winter because flowers are formed on this season's growth.

    Pruning resources online:

    Date: 2007-05-17
    Link to this record (permalink)

    Garden Tip

    Keywords: Pruning trees, Pruning

    Winter is a good time to prune because the branch structure of trees and shrubs is clearly visible. Winter is certainly not the only time for pruning, but the list of competing garden chores is typically shorter in winter. Here are a few websites to check out before pulling out the pruning saw:

    Date: 2006-03-20
    Link to this record (permalink)

    Garden Tip

    Keywords: Pruning trees, Pruning

    By Thanksgiving most leaves have fallen off deciduous trees. Some people feel a strong desire or obligation to prune when they see these naked trees. If you're one of these people remember that most trees and shrubs don't require regular pruning, other than to remove dead, dying or diseased branches. However, if some correction or thinning is necessary arm yourself with one of the excellent pruning books:

    • Cass Turnbull's Guide to Pruning: What, When, Where & How to Prune for a More Beautiful Garden (Sasquatch, $17.95) - Turnbull demystifies pruning with humor and helpful diagrams.
    • The Pruning of Trees, Shrubs and Conifers by George Brown (Timber, $29.95) - This classic reference work has been revised and enlarged by Tony Kirkham to reflect recent advancements in pruning; it includes a plant by plant guide to special considerations.
    • An Illustrated Guide to Pruning by Edward Gilman (Delmar, $26.25) - A text book for professionals or serious gardeners, this book includes information on training young trees and has many illustrations.

    Date: 2007-04-03
    Link to this record (permalink)

    Garden Tip

    Keywords: Tools and equipment, Pruning

    Use the right tool for the job. Bypass pruners (with blades arranged like scissors) make the cleanest cut. Anvil pruners may feel more powerful, but the blade tends to crush small branches, leaving a jagged wound more vulnerable to rot. But anvil pruners are essential if wrists are weak. If bypass pruners aren't working it's time to move up to a lopper or a pruning saw. For a concise discussion of all the various pruning tools go to: http://www.hort.purdue.edu/ext/pruningtools.html

    Date: 2007-04-03
    Link to this record (permalink)

    Garden Tip

    Keywords: Pruning shrubs, Plant training, Pruning trees, Pruning

    American Horticultural Society Pruning and Training. Christopher Brickell, editor. New York: DK publishing. 1996
    This book gives detailed instructions on how and when to prune trees, shrubs, fruit trees, vines and roses. With good basic background information on general pruning techniques, pruning guesswork is eliminated. The book also explains how to do specialized methods of training like turning your hedge into a living sculpture.

    Date: 2007-07-12
    Link to this record (permalink)

    Garden Tip

    Keywords: Plant diseases--Control, Tools and equipment, Pruning

    Wondering when is it necessary to clean or sterilize your pruning tools, and how to do it? Washington State University Extension horticulturist Linda Chalker-Scott offers excellent "how-to" advice. Make sure there is no excess dirt or debris on your pruners before you clean them. There are quite a few impractical or inadvisable methods (formalin? chlorine bleach? no!); her preference is to use ordinary household cleaners.

    Another factsheet discusses when to sterilize your tools. Chalker-Scott says that first you must know which pathogen is causing the disease. Then,

    • "if it's a virus or viroid, disinfect your tools.
    • if it's a vascular fungus or bacteria, and/or forms oozing cankers, disinfect your tools. Avoid cutting active, oozing cankers; wait until they dry.
    • if you are pruning irreplaceable plants, disinfect your tools.
    • choose a disinfectant treatment that has been shown to be effective through published research; I would probably not use alcohol but one of the common household cleaners at full strength."

    Date: 2014-10-17
    Link to this record (permalink)

    Guide to Pruning   by Cass Turnbull, 2012

    Reviewed by: Brian Thompson on 2013-04-01

    Guide to pruning book jacketCass Turnbull needs no introduction to our readers and a new book by her is a cause for celebration. Her "Guide to Pruning" is now available in its 3rd edition with three added chapters, including a much needed essay on Taming the Native-Plant Garden. She also addressed an impressive list of new plants not considered in the earlier editions, including "whackables" such as Lavatera and Perovskia. Oh, how I wish I had read about the dangers of whacking too soon--before making my mid-February cutbacks in my own garden.

    Excerpted from the Spring 2013 Arboretum Bulletin.

    Link to this review (permalink)

Didn't find an answer to your question? Ask us directly!

Browse keywords

Search Again: