Janet Carson is a horticulture specialist for the University of Arkansas Cooperative Extension Service. Write to her at P. O. Box 391, Little Rock, Ark. 72203, or e-mail her at jcarson@arkansason
line. com
QWe have
beautiful Wine & Roses weigela shrubs,
about 3 years old, and their showy blossoms were absolutely gorgeous this spring. My husband did a little conservative trimming, and they bloomed again a little bit in late summer. They are getting tall, and I think I want to keep them at a manageable height. When is the best time to prune back the branches and how should we do it ? I have the same issue with several butterfly bushes. Is it too late to prune now ? How is the best way to trim / prune ? AFor pruning questions, keep in mind what season the plants bloom — or at least are supposed to bloom. We often get errant flowers on a few spring-blooming plants in the fall, but their main flush is in the spring. Spring-blooming plants set flower buds in late summer to fall. Pruning should be done as soon after flowering in the spring as possible. This allows them ample time to recover and set plenty of flowers for the next year.
The weigela is a caneproducing plant that makes a living fountain in the landscape. To keep it free-flowing, prune immediately after bloom in the spring by removing up to one third of the older canes at the base. Pruning it now would remove next spring’s blooms. The butterfly bush blooms on new-season growth during the growing season. It should be pruned hard before new growth begins in late February to early March. Depending on what size plant you want, you can take it back by one half or almost to the ground each season.
QEvery year we get
something rolling itself
up in young canna leaves in our 6-year-old canna bed. We’ve noticed black specks, and the tightly rolled leaves never open but become lacy. In previous years we clipped them off as they occur, but this year I’m more aware of butterflies and beneficial insects in all their stages of life. I don’t want to be tossing away something that will be a butterfly or be helpful someday. None of the butterfly books I have mention cannas as a host plant. Just to be sure, can you please tell me what affects cannas this way ?
AThe problem is an insect
called the lesser canna
leaf roller (Geshna cannalis ) and seems to be getting worse all the time. The adult is a small, light brown moth. She lays eggs in groups of 6-15 on the upper surface of the canna leaf starting soon after the cannas have emerged in the spring. When the eggs hatch, the larvae tunnels into the leaf, leaving behind droppings or other debris as they feed. When they get to be about one week old the larvae initiate the leaf rolling, which helps protect them from predators and insecticides. The insects overwinter in a pupal form in the dead canna leaves. Removing all the old leaves and replacing with a fresh layer of mulch this fall can help you start the season clean. The moths won’t get active until the cannas emerge next spring, but there can be several generations each season. At the first sign of symptoms next season — either leaf rolling or droppings — spray BT (bacillus thuringiensis, found in insecticides including Bonide Thuricide and Dipel ) into the rolled leaf and the surrounding foliage. Cutting off heavily damaged leaves and destroying them is also helpful. QI hope you can identify a plant from a description. It is a hedge plant, or is used as one in this landscape. The shrub is thick-stemmed with alternate smooth-edged leaves with a slight rippling effect. The undersides of the leaves are speckled. The stems are white with tiny speckles similar to what is on the underside of the leaf. It had a 1 / 2-inch white tubular bloom in October that smelled really good.
AI believe it is elaeagnus
pungens. It is an
evergreen hedge or large shrub with a silvery back to the leaf coupled with the small brown scales you noticed. Some folks think the brown scales are an insect infestation, but they are a natural occurrence. The fall blooms smell as sweet as gardenias but are hidden within the plant. Although not showy in appearance, the plants’ fragrance spreads throughout the landscape in a season when we need a little boost.
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