Pinching rhododendron buds

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?

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.

Pruning shrubs, Rhododendron

Reviving Philadelphus

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?

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.”

Failure to flower, Fertilizers, Philadelphus, Pruning shrubs

Pruning snowberry bushes

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

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.

pruning and caring for rhododendrons

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?

The American Rhododendron Society’s page on pruning should be helpful. It describes clean-up pruning, shape pruning, and rejuvenation pruning.

Seattle author Cass Turnbull’s Guide to Pruning (Sasquatch Books, 2012). Plant Amnesty, founded by Turnbull, also has information on pruning an overgrown rhododendron.

The Rhododendron Species Foundation in Federal Way is a place you can visit to get an idea of the wide range of species available. They also have general information on rhododendron care on their website.

The Miller Library has a substantial collection of books on rhododendrons, including quite a few by Pacific Northwest authors, and you can browse them or check them out to see which species and varieties might be more suitable for your garden.

pruning native roses

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?

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 are general guides on rose pruning in the Northwest, from the Seattle Rose Society and Roses for the Pacific Northwest.

dogwood disease and coppicing smoke tree

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

Here is information about dogwoods and anthracnose from University of Massachusetts-Amherst.

Washington State University’s HortSense website has a factsheet on anthracnose for home gardeners which recommends the following:

Plant species which are anthracnose-resistant. Dogwoods showing very good resistance include: C. kousa ‘Beni Fuji’, C. kousa ‘China Girl’, C. kousa ‘Lance Leaf’, C. kousa ‘Milky Way’, C. kousa ‘Porlock’, C. kousa ‘Silver Cup’, C. kousa ‘Snow Bird’, C. kousa ‘Speciosa’, C. kousa ‘Summer Majesty’, C. kousa ‘Tsukabo-no-nine’, C. kousa ‘Wilton’, C. kousa ‘Dwarf Pink’, C. kousa ‘Ed Mezett’, C. kousa ‘Satomi’, C. florida hybrids, C. florida ‘Spring Grove’, C. florida ‘Sunset’, C. racemosa, C. canadensis, C. mas, C. alba, C. alternifola, C. sericea, and C. sericea ‘Flaviramea’.
Where practical, prune and destroy infected twigs to prevent overwintering of the disease.
Rake and destroy all fallen leaves, both during the summer and in the fall.
Do not compost diseased materials.

Oregon State University Extension’s Online Guide to Plant Disease Control (aimed at professional horticulturists) 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 (smoke tree) among those plants which respond well to this pruning technique.

Buxus renovation pruning

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.

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.

Pruning Daphnes

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.

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 description of the grab-and-snip pruning technique
for mounding shrubs may be found in Cass Turnbull’s The Complete
Guide to Landscape Design, Renovation and Maintenance (2006).
Although she advises against pruning Daphnes unless it’s absolutely necessary,
this technique can be used in spring. Cut off or cut back to a side branch and
branch that is lying on the ground or extending into places where you do not
want it to go. You can also remove some of the longest branches that are lying on top of other branches.

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.

Hibiscus plant care and pruning

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?

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.

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

on pruning lamb’s ear and Himalayan honeysuckle

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?

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.