pruning winter-damaged plants

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.”

pruning wisteria

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.”

on pruning junipers

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
Excerpt:
“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.

pruning and training grapes

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.”

pruning Arbutus unedo

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.

III. TREE-LIKES

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.

Pruning roses

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.

on pruning raspberries

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.

pruning and maintaining ferns

I have questions on general maintenance for the ferns in my garden. It is winter and the wood ferns (now about 4 feet in diameter) have fronds which are now partially brown. The deer ferns look similarly forlorn.
Should I prune all the old fronds off and let the new ones take over? How and when to do this without damaging emerging new growth?

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 (this can be risky: be careful not to cut the new fronds), or according to Pacific Northwest 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. The same is true for deer fern (Blechnum spicant, now renamed Struthiopteris spicant): “Old fronds should be cut back in late winter or early spring before new growth starts.”

This is a good general guide for pruning maintenance of ferns, written by Richie Steffen of the Hardy Fern Foundation. The first thing he points out is that cutting back ferns is purely an aesthetic choice; it is not necessary. If you do want to cut back, consider the type of fern: is it evergreen, winter-green, deciduous, or semi-evergreen? The answer to this question will determine the best practice.

on pruning combination fruit trees

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 can’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.

best time to prune Pieris

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.