Should you remove old blooms from rhododendrons and, if you should, which is best: to prune or snap them off?
Here is what the American Rhododendron Society says on the subject:
“It is desirable, with the large flowered rhododendrons, to remove the withered flower clusters after the blooming season. This is fairly easily done as the central axis of the cluster, usually called a truss, will break free from the plant with a quick snap of the thumb pushing on the side, or can be cut off with a hand pruner. With the smaller flowered rhododendrons and azaleas, dead-heading is labor intensive and and generally is not required.
Dead-heading is usually done to make the bush look more attractive, to reduce the prevalence of fungus and to prevent a heavy set of seed. If it is not possible to remove the old flowers, it is usually not too detrimental, but flowering the next year may be reduced.”
I have several mature rhododendrons in my own garden, and I deadhead the parts of the shrubs which are easily reachable, leaving the other areas to their own devices. For me, it’s an aesthetic choice, and I would probably do them all if I could reach and if I didn’t get very tired of the task. (It’s hard to do well with gloves since you can’t easily feel the right place to snap off the flower head, but it’s sticky work without the gloves.) I’ve never tried pruning them off, because it seems less precise (leaves a bit of a stub), but if rhododendron experts approve (as indicated above), I may just try it this year.
I have heard that raking to clean up leaves in the fall is no longer a recommended practice, and that it is more sustainable to leave the leaves alone, to decompose in place. Can you provide information supporting this?
This is a complex issue without a single simple answer. Letting leaves lie in place is fine in some situations and not in others. Undisturbed leaves can be a beneficial mulch in the garden, but not all leaves, and not in all circumstances.
Here are a few suggestions:
Don’t leave diseased or insect-affected leaves on the ground. (As a precaution, I always rake up and remove leaves of fruit trees.)
Be aware that a thick mat of leaves can make a great hiding place for slugs and snails, and early stages of stink bugs. Learn to recognize their pearly little eggs!
If you have thick or leathery leaves (such as oak and magnolia), a mulching mower might be a good way of breaking them down to use as mulch.
If leaves are slippery or are going to obscure uneven terrain that might cause people to trip or fall, rake them.
If you do decide to collect leaves into a pile, raking is a better method than using a leaf blower (and if you must blow, use an electric or battery-operated blower, which is still noise pollution but at least not air pollution).
In their 2014 book The Living Landscape: Designing for Beauty and Biodiversity in the Home Garden (page 146), Rick Darke and Doug Tallamy do advocate letting leaves lie in the garden, but they recommend running over them with a mower first if you want to have finer material for mulching (so as not to smother fragile plants)—which means they would need to be raked into a mowable pile first. Another way to make leaves more useful as mulch is to compost them for a year—which would also require raking them up and putting them in a pile. Generally, though, the authors favor the let-it-lie philosophy: “In many places, the most conserving, functional, low-maintenance approach to autumn leaves is to let them lie where they fall. This is exactly what happens in unmanaged forest ecosystems. Though a too-heavy leaf layer can have a negative effect on delicate herbaceous plants, most trees and shrubs and a wide range of sturdy perennial herbs grow well under natural leaf fall.”
I will point out that a tiny urban garden is quite different from an unmanaged forest ecosystem, so sometimes we need to rake leaves where they impede access to paths, steps, sidewalks, etc. And again, consideration should be given to preventive measures. Don’t let lie the leaves of any plant you know to be struggling with pests and diseases.
When and how do I prune my lavatera tree? We used to think this plant was a bush!
Lavatera does tend to grow vigorously, and can get quite woody. You can cut a third off the top of each stem in late autumn, and then in mid-spring finish your pruning by cutting all the previous year’s growth to about 6 inches from the ground. Hard pruning will encourage flowering, and keep the plant more compact. New shoots may be slow to appear (may not happen until early summer).
In my experience, a small start of Lavatera turned into an 8 foot tree in one year, and because it was in a spot where a tree was not desirable, I took a cutting, then dug up the plant, and started afresh–but this may be an extreme solution to the problem!
I have a dark purple lilac tree growing on the north side of my home. It does not get a lot of sunlight. I am wondering about replanting it somewhere else in the yard. When can I do this?
Lilacs should be able to tolerate moderate shade, according to The Plant Care Manual by Stefan Buczacki (Crown Publishers, 1993). You can move it to a sunnier location to see if it will thrive there.
The best time to transplant a lilac is before it leafs out (late winter, when it is dormant) but apparently they are somewhat tolerant of being moved at less-than-ideal times. The University of British Columbia Botanical Garden discussion forum also recommends transplanting lilacs in dormancy. Blooming should not be affected, unless your bush is already leafed out and in bud.
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?
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:
Heaths and Heathers Nursery
Dayton Nursery
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