Garden Doctors: Can smoke tree recover from bad pruning job?

Mari asks: When is the best time to prune my smoke tree? A problem occurred when my gardener decided to shear the entire bush into a round blob. Now, how and when do I get it back into its normal growth pattern and shape? Also, I fear I have lost the unusual 'smoke' that adds to its beauty.

Smoke tree, botanically known as Cotinus coggygria, does require some pruning to keep it in shape and prevent it from becoming a shrub that can overtake the site where it is planted. Unfortunately, the pruning you described will encourage even more unshapely and rapid growth. But it is a forgiving deciduous shrub/tree that is fairly drought tolerant, has colorful purple leaves (a favorite, 'Royal Purple' variety), beautiful fall foliage and is certainly a stunning specimen addition to any garden when situated in a sunny location and given room to grow and show off its qualities.

The best time to prune a Cotinus is in early spring before the sap starts to flow. The timing is important since the sap will attract insects and pruning wounds do not heal readily. How to know if the sap is flowing: make a small cut and if you see a lot of sticky sap, delay the pruning. That may mean waiting until next late winter or early spring.

Pruning in late winter will rejuvenate the shrub, but it will also encourage more new growth than you anticipated. You may have an abundance of new growth after the recent shearing, but still have time to gradually correct the poor pruning in early spring. It may take a couple of seasons to correct the mistake; this is not unusual and applies to many shrubs. After all, gardening is a fun experiment and full of errors, but we have many opportunities to learn and correct mistakes!

Waiting until late winter or early spring to prune will create new flower buds on the plant. Try to identify and not remove the forming flower buds. The billowy pinkish flower clusters in late spring and early summer that appear smoke-like gives Cotinus its common name: smoke tree.

Future pruning goals: Prune to maintain and manage its natural shape. The smoke tree does exhibit a natural splayed or rangy appearance, but that form can be modified somewhat by selective pruning. Open up the shrub for better air circulation; accomplish this by completely removing old stems to the ground (no tip pruning).

Cut out cross branches that are rubbing against each other. Remove all twiggy stems and those non-supporting small branches back to main branches.

Cotinus species and cultivars can vary from 10 to 12-15 feet in height and as wide. Some can reach a height of 20-25 feet. The cultivar 'Royal Purple' is a popular selection but there are many other choices.

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Judith writes: You recently wrote about Amaryllis bulbs and briefly referred to Hippeastrum, the forced, trumpet-shaped blooming bulbs sold in boxes during the holidays. Mine is healthy and has pushed out a tall stem, but now the stem is falling over. What caused this?

The stalk is hollow and cannot support the multi-trumpet-shaped blooms. Find a small stem or purchase a small nursery support stick, insert it into the soil next to the weak stalk and tie a piece of raffia around the two for support. This should do the trick. Taking care of the problem of stalks falling over early enough (when first forcing the bulb) solves the problem. They are still available for purchase in the garden centers so there is time to enjoy the brilliant-colored blooms.

Amaryllis belladonna does not have a hollow stalk and stands upright without support.

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Javier asks: I live at the bottom of a hill in Santa Rosa and my citrus are always hit by frost, but my neighbor halfway up the hill never seems to have that problem with her citrus. What's up?

The topography of the land (your micro-climate) affects frost prevalence. Cool air always settles at the bottom of a slope because it is heavier than warm air. Frost damage is always more prevalent at the bottom of a slope. The planting location of frost-tender plants is important. When possible, plant along a south-facing wall that will radiate more heat. Take temperature readings around your house and you will see the temperature variations that occur. It is interesting to see the warmer temperatures under protective trees and under eaves.

We always talk about frost protection, but what most gardeners don't know is that moist soil will hold four times more heat than a dry soil and will conduct heat to the soil surface faster than a dry soil, aidin

g in frost prevention. We are fortunate to have had rain that will help prevent frost damage. As an example: We hadn't had any rain to speak of and the soil was pretty dry under our own citrus. Lower temperatures were expected, so I irrigated the soil for further protection. It worked.

You will still need to continue with other methods of frost protection, given your location where the cold air settles.

Dana Lozano and Gwen Kilchherr are garden consultants. Send your gardening questions to The Garden Doctors, at pdgardendoctor@gmail.com. The Garden Doctors can answer questions only through their column, which appears twice a month in the newspaper and online at pressdemocrat.com.