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Search Results for ' Pruning shrubs'

PAL Questions: 15 - Garden Tools: 1

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Keywords: Pruning shrubs, Rhododendron

PAL Question:

I need to know what to do with a rhododendron that has grown too big. I want to keep it, since it is a bookend to another plant. Can I cut it back, and if so, how far and when? Will it be okay and continue to bloom if I cut it back? Could you suggest something and also suggest a really good book on care, etc., for rhodies?

View Answer:

For general care, quick information is available at

1) The American Rhododendron Society, click on "Need Help Growing Rhododendrons?"

2) The Seattle Rhododendron Society, click on "Care and Maintenance of Rhododendrons."

For more extensive information, there are scores of great books. A good one that includes specifics about rhodies is Cass Turnbull's Guide to Pruning (Cass Turnbull, 2004). Plant Amnesty, founded by Turnbull, also has information on pruning an overgrown rhododendron.

You can also select one by thumbing through the paperbacks available at (almost) all nurseries. Sunset Publishing, American Horticultural Society and Ortho Books are reliable publishers.

As an aside, there were some ancient, neglected, potentially beautiful rhodies at my home. They were pruned slowly over 3 to 4 years and look great now. So, don't be shy!

Season All Season
Date 2007-12-06
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Keywords: Pruning shrubs, Rhododendron

PAL Question:

A friend was told that pinching out growth buds before they begin to elongate as a means of shaping young rhododendrons would only stimulate buds further down the stems that were less than 4 years old - older than that and the growth buds would no longer be viable. I cannot find any information to suggest 4 years viability of dormant buds to be true, or untrue. Can you help?

View Answer:

Though pinching encourages multiple branching lower down the stem, I find no reference to it being done at a particular age.

“This practice (pinching) is recommended for most larger rhododendrons until they reach flowering size...”
(Source: A Plantsman’s Guide to Rhododendrons, by K. Cox, 1989, p. 101)

That statement indicates a younger plant, but the author then mentions several exceptions.

Here is some how-to information about pruning online:
7 Solutions to the Too-Big Rhododendron.

Season Spring
Date 2008-01-17
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Keywords: Pruning shrubs, Cotinus coggygria, Cornaceae (Dogwood family), Trees--Diseases and pests

PAL Question:

Can you give me some general information about Dogwoods and anthracnose? Also, I would like to know about coppicing Cotinus coggygria.

View Answer:

Here is information about dogwoods and anthracnose:
The U.S. Forest Service article entitled How to Identify and Control Dogwood Anthracnose, may be of use. Although it is somewhat technical in its language, there are excellent pictures and a section about methods of control.
Master Garden Products.com provides a short article about Dogwood Anthracnose that contains a What to Do list.
Oregon State University Extension's Online Guide to Plant Disease Control provides a corroborating list of cultural controls for Anthracnose and adds an extensive list of chemical controls. It's always best to use cultural controls and avoid chemical ones if you can. Some dogwoods in the Pacific Northwest have been known to recover from anthracnose, according to Douglas Justice of University of British Columbia Botanical Garden.

The Royal Horticultural Society has useful general information on coppicing, and includes Cotinus coggygria among those plants which respond well to this pruning technique.

Season All Season
Date 2006-12-08
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Keywords: Pruning shrubs, Hibiscus

PAL Question:

How do we prune a Hibiscus tree that is about 3 feet tall? The plants are located in a container outside of our senior center. They wintered inside and are now too bushy at the top. How do we prune so they are more compact? What is the correct way to care for these wonderful flowering trees?

View Answer:

It sounds like you have Hibiscus rosa-sinensis---the tropical evergreen shrub. Late spring is the time to prune. According to the American Horticultural Society Pruning & Training book: Prune established plants by cutting back main shoots by as much as one-third, and shorten laterals, leaving two or three buds. Dead wood attracts canker, so it should be removed promptly. To renovate completely, remove older branches entirely and cut the remainder back hard. The response is usually good, but if most stems have died back, it is best to replace the plant.
(Source: American Horticultural Society Pruning & Training, ed. by C. Brickell, 1996, p. 201).

Other pruning information is available from Hidden Valley Hibiscus or from the Queen of the Tropics website (click on Fertilizer, Insecticide, and Pruning).

Also, my personal experience with a 10-year-old Hibiscus is that pinching out tips of stems in spring and summer increases flower production.

Season Spring
Date 2008-01-24
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Keywords: Pruning shrubs, Shrubs--Care and maintenance, Calluna, Erica

PAL Question:

How do I care now, in the fall, for very well established, huge (in some cases) Callunas? Do they get sheared? If so, how many times a year, and how far back? Also, how do I prune my heaths?

View Answer:

The American Horticultural Society Pruning and Training Manual, ed. by C. Brickell, 1996, p. 183, 193 recommends pruning Calluna (heather) in the same way as Erica cinerea. Prune or trim lightly in early spring, cutting stems back where possible to strong shoots below the spent flower cluster.

Local pruning expert Cass Turnbull of Plant Amnesty says the following about heaths and heathers (Erica and Calluna) in her Guide to Pruning (Sasquatch Books, 2006): "Spring bloomers are sheared shortly after blooming (in the spring). Summer/fall bloomers are also sheared in the early spring (just as new growth starts), so that the attractive seed heads are left in view all winter. An annual light shearing is all that is needed. Don't wait. Do it now before the plants get too old and woody. When cut too far into old brown, barren branches, a plant may not break bud and green back up. If you have inherited a mature yard, it may be necessary to severely prune an old neglected heather. It will either regenerate or die. Probably the latter. An exception is the tree heath, Erica arborea, which (...) responds well to radical renovation."

For further information, consult the following websites of nurseries specializing in these plants:
http://www.heathsandheathers.com/cart1/page6.html
http://www.daytonnursery.com/tips/Heaths%20&%20Heathers.htm

Season Fall
Date 2008-01-31
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Keywords: Pruning shrubs, Buxus

PAL Question:

To renovate old Buxus hedge, when is the best time to cut back to 15-30 cm shoots? It appears that new shoots are pushing through now. My American Horticulture Society Pruning and Training book suggests late spring, but that may not apply to Seattle.

View Answer:

I consulted a local organization, Plant Amnesty, and their information sheet on Buxus says that April is the best time to prune. It is important not to prune when it is either too cold (leaves will turn grey) or too hot (same result).

Peter McHoy's book, A Practical Guide to Pruning, also says to do your renovation pruning in mid- to late spring, and further suggests that drastically reducing the height of the hedge should be done in stages, over two to three years.

Season Spring
Date 2006-11-28
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Keywords: Rosa gymnocarpa, Rosa nutkana, Pruning shrubs, Native plants--Washington

PAL Question:

What do the experts recommend regarding time(s) to prune the native roses, Rosa nutkana and Rosa gymnocarpa? I am interested in controlling their growth without losing bloom and/or rose hips. Do either or both of them bloom on second year wood?

View Answer:

Peter McHoy's A Practical Guide to Pruning says that the pruning method would follow that of vigorous species roses, which produce flowers on old wood. He says to remove any dead wood in early spring (similar to 'late winter').

The Royal Horticultural Society A to Z Encyclopedia of Garden Plants (edited by Christopher Brickell, Dorling Kindersley, 1996) says to prune species roses as needed only, cutting out one fifth to one fourth of the oldest stems. A Pacific Northwest native wildlife gardening source on the web recommends only pruning out dead wood, and otherwise leaving it be.

Since Rosa gymnocarpa is also once-flowering, it should be pruned--if you need to prune it at all--just after flowering. The following is a general guide on rose pruning in the Northwest, from the Olympia Rose Society.

Season All Season
Date 2006-12-08
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Keywords: Arbutus unedo, Pruning shrubs, Osmanthus, Quercus, Viburnum, Pruning trees

PAL Question:

When is the proper time to prune Arbutus unedo? How much can be pruned at a given time? Same question for Osmanthus decorus, Viburnum odoratissimum, and Quercus reticulata.

View Answer:

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.

The book Pruning: A Practical Guide by Peter McHoy (Abbeville Press, 1993) says that Osmanthus decorus can be clipped in late summer. If you want to limit its size without clipping, prune back long shoots to points far inside the shrub in late spring or early summer, after flowering. If the plant is overgrown, you can spread this type of pruning over two or three years, but do not do it annually. I am not familiar with this species of Osmanthus, but I do know Osmanthus delavayi, and grow it as a hedge. It is sheared after it flowers, and then probably two more times before winter. I did have to prune the top back quite hard last year, and this did not seem to cause any problems, but O. decorus may have different needs.

I could not find information about Viburnum odoratissimum specifically, but most pruning books have general guidelines for Viburnum species. Unless you do not mind losing the flowers, it is best to prune when flowering is done. If you are growing V. odoratissimum as a tree, then special pruning may be needed. George E. Brown's The Pruning of Trees, Shrubs and Conifers (Timber Press, 2004) says V. odoratissimum is somewhat tender, and may grow best as a standing bush with the protection of a wall, using ties in places to keep it close to the wall. The only pruning he mentions is cutting out older wood after flowering, and tying new growth back to the wall (if you are growing your plant in a site where you can do this).

According to the Peter McHoy book, oaks do not require routine pruning. Brown's book says not to prune oaks between mid-spring and mid-summer, as a means of protecting against oak wilt and beetle infestation. If you must prune, do it in winter.

Quercus reticulata is not a common tree, nor are the species of Viburnum and Osmanthus you are growing. Unless there are compelling reasons to prune harder, I would suggest sticking to the 3 D's of pruning: take out only dead, diseased, and disordered branches. Another general rule of thumb is never to remove more than 1/3 of the plant at one time. You might want to consult a certified arborist as well. You can find arborists through Plant Amnesty's referral service or the Pacific Northwest Chapter of the International Society of Arboriculture.

Season All Season
Date 2008-03-19
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Keywords: Failure to flower, Stachys, Pruning shrubs, Leycesteria

PAL Question:

I have a question about cutting back plants. I have some non-flowering lamb's ear that is looking quite scraggly. How far back do I cut these, and when?

Also, how far back should I cut my Himalayan honeysuckle? We planted it 2 years ago, and last summer it got 5 feet high!

Also, last year my Hebe plants did not flower. We have Hebe anomala purpurea 'Nana'. I have recently checked the tags they came with, and it doesn't mention that it flowers. Is this a non-flowering Hebe? Although the shrubs are lovely, I was hoping for the type that flowers. If we decide to move them, when would be the best time to transplant them?

View Answer:

Yes, Stachys (lamb's ears) can look pretty ragged after winter. I'm guessing you are growing Stachys byzantina 'Silver Carpet' or a similar cultivar, which doesn't flower. If you look closely, you should see signs of new growth. I would suggest cutting back all the tattered or dried leaves as far as you are able, without injuring new growth. March is a good time to divide the plant if you like. (I have shared this plant many times and moved clumps to new locations. It is quite tough, and will transplant easily.)

Himalayan honeysuckle, Leycesteria formosa, can be cut back to the ground (or within a few inches of the ground) in late winter or early spring,according to Sunset Western Garden Book. The website of Rainyside Gardeners (a Northwest site) has a useful page on Leycesteria formosa.

According to Hebes: A Guide to Species, Hybrids, and Allied Genera by Lawrie Metcalf (Timber Press, 2006), Hebe anomala 'Purpurea' is a synonym for Hebe odora 'Purpurea' which is supposed to have a lot of flowers. He doesn't mention the dwarf variety, 'Nana,' but I assume it would have similar attributes. Even with the nomenclature confusion, there seems to be some consensus about the floriferous qualities of the plant: Douglas Chalk's Hebes & Parahebes (Christopher Helm, 1988) lists Hebe 'Anomala' as a cultivar of Hebe odora, and he too says it has lots of flowers. Are your Hebes getting enough sun? Some Hebes will flower in partly shady sites, but the flowering will be diminished. Could they have been pruned accidentally, just before flowering? Another possibility is that the plants are not mature enough to flower. The Metcalf book mentions a few species which can take years to produce flowers. He also says that flowers are enhanced by chilling followed by warmth, over a period of about 12 weeks. The number of hours of daylight to which the plants are exposed is also a factor. As far as transplanting, doing it in March should be fine. It isn't too hot, and we are likely to have the occasional rain,but you should still water well when you first move them.

Season All Season
Date 2008-04-11
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Keywords: Pruning shrubs, Daphne

PAL Question:

I have some very healthy daphne bushes full of blooms and I am wondering if and how I should deadhead them... or do some judicious pruning now that their flowering season is about over. I live on Whidbey Island, Washington. The plants are two years old and doing very well where they are planted.

View Answer:

The standard advice with Daphnes is that they are usually best left unpruned. If you need to keep them compact, you may be able to do a little light pruning. Peter McHoy, author of Pruning: A Practical Guide (Abbeville Press, 1993) says that no Daphne species needs routine pruning, but it is a good idea to remove straggly shoots in early spring. If you do prune hard, it will be a year before flowering returns to normal. Writing in the New York Times, August 3, 2006, Leslie Land asks John Bieber of the Daphne Society about how to prune if you must: "Choose a dry morning shortly after spring bloom is over. Sharpen the shears. Cut back lightly; severe pruning is always a gamble. It is safer to take two or three springs to downsize a badly overgrown plant."

Another resource, with a good illustration of the grab-and-snip pruning technique for mounding shrubs is from Plant Amnesty, published in Cass Turnbull's The Complete Guide to Landscape Design, Renovation and Maintenance (2006).

I would err on the side of conservatism, as Daphnes can be temperamental. Since yours are doing so well, I suggest that you only remove the bare minimum of leggy limbs, if you decide to prune.

Season All Season
Date 2008-04-23
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Keywords: Symphoricarpos albus, Pruning shrubs

PAL Question:

How and when do I prune snowberry (Symphoricarpos albus)?

View Answer:

Symphoricarpos albus is a suckering plant, so you can literally prune it to the ground. It will probably come back healthier than ever (assuming it's healthy at the time), especially if you do it in early spring. Snowberry can take over and will likely crowd out lower plants; keeping it in check can be done with a lawn mower, weed eater, or by hand pruning. I suppose you could shear it or selectively prune it, but to maintain its natural growth habit, pruning it to the ground is your best bet.

Season Spring
Date 2009-03-05
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Keywords: Pruning shrubs, Transplanting, Ceanothus

PAL Question:

I have a mature Ceanothus 'Victoria' that I'd like to prune and transplant. When is a good time to do this? It seems as if it has a deep root system.

View Answer:

Ceanothus 'Victoria' can be a bit difficult to transplant because the root systems are extensive, as you noted, but it is worth a try. I have transplanted this cultivar both successfully and unsuccessfully.

I would recommend either that you do not prune them or that you wait until August. You do not want them to grow much before you transplant them, and pruning during the growing season will encourage growth. If you prune them in August, they will grow very little.

Extensive pruning before transplanting sets up competition between the root system and the upper plant (responding to the pruning), as far as the plant's resources are concerned. After transplanting, you want energy directed toward the roots so that they might take hold and also so that growth above ground slows. If you choose to prune the shrubs, I recommend that you prune as little as possible. Prune from the inside, thinning and taking out dead branches, and removing a few lower limbs. You can also cut back some of the longer limbs, as this shrub can handle 'heading back,' as this type of pruning is called. Please note that this shrub is genetically programmed to get quite large, and pruning will not prevent this. Be sure the new spot can handle a shrub that wants to grow 8 to 10 feet up and out (possibly more!).

With this in mind, you can consider transplanting the shrub in the fall. I recommend October or later so that you can avoid a hot spell (which may promote upper growth and/or place the plant under stress). When you dig up the root system, retain as many of the roots and their native soil (surrounding them and holding them together) as you can. You will have to cut the deep taproot(s); that is unavoidable. The tiny, thread-like roots are more important to retain.

When you dig the hole, make it big enough to accommodate the soil around the roots as well as a bit of filler. You don't need to add new soil; simply backfill with the soil you dug out. You may have to water a bit, even in the fall, until our rainy season begins. You don't need to saturate the roots, but don't allow them to dry out.

Season All Season
Date 2009-06-18
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Keywords: Prunus laurocerasus, Pruning shrubs, Hedges

PAL Question:

We have inherited a 25-foot tall English laurel hedge. The former owner never took care of of so most of the 'inside' is just dead branches, but the rest is VERY healthy. Our neighbors would like us to prune it so it's not obstructing their view, and I'd like to reduce its size so I don't need to climb a ladder to prune it in the future. Can I cut it back severely, and regrow it into a more manageable hedge? I don't have the energy to remove it entirely.

View Answer:

I doubt that anyone would ever consider English laurel (Prunus laurocerasus) a manageable hedge plant since what it really wants is to be a tree, but since you want to keep it as a screen, you should be able to cut it back quite hard. It will most likely put on new growth. However, it will look fairly awful while you are waiting for this to happen. According to local Plant Amnesty pruning expert Cass Turnbull (in her Guide to Pruning, Sasquatch Books, 2006), "radical renovations of laurel hedges are common. In the spring, saw the overgrown hedge into the desired shape, except perhaps a foot or two smaller than the final desired size. That's because it will need that room to resprout and be sheared into a thick green coat again. Be sure to cut your hedge narrow as well as short. It should be narrow enough for one gardener to reach across with a hedge shear. I have only seen one laurel hedge that didn't recover from this radical treatment. (...) Please avoid heavy pruning on a hot July or August day, as you might burn up some internal leaves or scald the bark."

Season All Season
Date 2009-08-07
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Keywords: Pruning shrubs, Ceanothus

PAL Question:

How do I go about pruning Ceanothus?

View Answer:

My impression is that in general, Ceanothus should be pruned with a light touch. Portland gardening expert Ketzel Levine has some opinions on this topic:

"You can certainly prune Ceanothus but there is a bit of a trick. First of all never prune any stems that are larger than 1/4" wide. Instead prune the very tips of each branch back to where you want it to be. And, since ceanothus bloom on 'new' wood, this should provide you with an even more spectacular show next year. Prune after the plants are through flowering; at that time you can also remove the spent flower spikes which will also help it look less wild."

Ceanothus by David Fross and Dieter Wilken (Timber Press, 2006) says that "an annual trimming of the new growth will maintain a more compact form and improve the appearance of most species. The removal of spent flowers and fruit improves the vigor of many cultivars and will produce a tidier form. Taller species can be trained into small trees with early pruning, and the removal of interior dead wood as plants age produces a cleaner appearance. Once the arborescent character is achieved it is easily maintained and requires minimal effort. Shearing for hedges and formal effect is tolerated by most species if cutting into woody tissue is avoided. Prune immediately after flowering, and only back to the new year's flush of growth." The authors mention that although it requires a lot of work, there are some species which can also be trained as small hedges or as trellis plants.

Here is the Royal Horticultural Society's guidance on pruning evergreen Ceanothus species: "Routine pruning is not essential and in fact are best not pruned. If grown as a bush, promote branching by pinch-pruning the soft tips on young plants in spring. Use secateurs to shorten over-long branches by up to a half in midsummer after flowering. Do not cut into older wood as the stumps may not regrow."

Season All Season
Date 2010-08-26
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Keywords: Philadelphus, Failure to flower, Pruning shrubs, Fertilizers

PAL Question:

I just bought a house with a garden which has good bones, but has been untended for a long time. I believe the garden has 4 Philadelphus X virginalis 'Minnesota Snowflake' plants. They are deciduous in the winter, and they have greened up nicely in the summer. They are about 6 feet tall. On the 4 plants, this first summer, I've only seen 2 flowers. Can these shrubs be salvaged by using a blooming (high in phosphorus) fertilizer? Or do they need something else?

View Answer:

The three things I would ask about Philadelphus with few flowers:

  • Are they in full sun? (Sun is needed for best flowering results.)
  • Have they been pruned and, if so, when? (Pruning is best done in late summer, after flowering.)
  • Are they growing near a lawn or other area which receives fertilizer that is higher in Nitrogen (N) than Phosphorus (P) or Potassium (K)?

I would recommend that you test the soil before embarking on a plan of fertilization, unless you are adding a mulch such as compost, which releases its nutrients slowly. Philadelphus is usually considered a light feeder (i.e., it doesn't require a lot of supplemental fertilizer).

As far as a future pruning regime for the shrubs, Jacqueline Heriteau's Complete Trees, Shrubs & Hedges: Secrets for Selection and Care (2005) says that Philadelphus "blooms on the previous year's growth. A light annual pruning of older branches right after flowering keeps mock orange shapely and productive. Branches more than five years old should be removed in winter or early spring."

Season All Season
Date 2011-07-12
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Keywords: Pruning trees, Pruning shrubs, Pruning, Plant training

Garden Tool:

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.

Season: All Season
Date: 2007-07-12
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June 24 2013 12:55:25