Q: Can I prune my six-foot hybrid rose bush now? Its an old one and not doing well. A few roses bloomed but there are no more buds on the bush.
Florence Salama
A: Most roses are pruned in February, but I dont see any problem with doing minor pruning now. But it should be pruned as soon as possible because the cutbacks will trigger new growth.
It takes several months for new growth to mature enough to withstand severe frosts in winter. Major cold snaps will cause immature growth to die back. But since your bush is old and not doing well, perhaps it would be better to renovate it more thoroughly.
You could begin this in the dormant season (between mid-November and early February) by cutting back half to one-third of the stems almost to the ground. Be sure to leave a few inches of stem above the graft. This pruning should trigger some dormant stem buds into growth.
This is a drastic pruning that should be carried out over two or three years. Dont cut everything down at once because this could kill the rose. Spreading the work over two years should be successful. Three years is a little safer.
Q: I recently trimmed the laurel hedge and noticed a number of small black flies that seemed to envelop the new growth in certain places on the hedge. I was wondering if the new growth gave off a sweet-smelling odour or released some sweet liquid that would attract the flies. There doesnt seem to be any damage to the leaves.
Should I be spraying them with an insecticide or just cut the new growth away and hopefully get rid of the flies in the process?
Brian Cronkhite
A: I wonder if some of these flies are clinging to the growth and not flying at all? Black aphids love new growth and some of them have wings.
If all of them are flies, the affliction will be cyclical. Youre quite right about the distinctive small of laurel leaves and laurel flowers. They have the same smell but stronger and always attract hordes of flies.
But if they are aphids clinging to the new growth, your idea of removing that growth is really the best way of improving the situation and avoiding the expense and possible health risks of insecticide. Laurel is very quick to re-shoot.
Q: I have a hardy hibiscus plant that weve had for many years. In the last two years, only some of the branches have leaves and flowers. Can you help?
Melanie Sabourin
A: The branches with no leaves or flowers are probably dead. But check this by scratching the bark on each branch until you can see the tissue underneath. If its brown, the branch is dead and should be pruned off.
Any branches with green tissue underneath should be left for a couple of years. Meanwhile, give your hibiscus tree much more water in dry spells and a rich, nutritious mulch. This can be manure, Sea Soil or compost.
Trees and shrubs often abandon branches if theyre not getting enough water or nourishment to support the top growth.
Also, older trees and shrubs can begin having health problems just because of aging. I wonder how old your hardy hibiscus is.
Anne Marrison is happy to answer garden questions. Send them to [email protected].
