Q I have two climbing roses. The plants are very tall but they never bloom. Is there some way to get them to bloom, or should I just get rid of them?
A There are a couple of things to consider before you give your roses the ax. First, are your roses growing in the right place? Roses need to be planted in full sun to grow and bloom well. They also need a good loam soil (not overly wet, overly dry or heavily compacted) for best growth. While roses need regular fertilization, you should avoid giving them too much nitrogen, since this can make the plant produce lots of lush foliage at the expense of flower production. Remember that fertilizer applied to lawns can also reach the roots of other plants growing in or near the lawn.
The other major consideration is what kind of roses these are. Several classifications include climbing types. If your roses are climbing hybrid teas or grandifloras ('America,' 'Blaze' and 'Golden Showers' are popular cultivars), the canes are not hardy enough to survive our winters without protection. The best way to protect the canes is to lay them down along the ground and mound soil over them, followed by a thick layer of straw or bags of dry leaves. If your roses have not been protected, they may have died back to the graft union. The canes that have come up may be the understock, in which case the plant may not bloom, or if it does the flowers will be quite different from the cultivar that had been grafted on top. If this is the case, you should discard the plant.
Fortunately, there are some hardy shrub roses that can be treated as climbing roses. These roses produce long canes, but don't require winter protection. 'William Baffin' and 'John Cabot' -- both from the Explorer Series of roses from Canada -- produce long, vigorous canes that can be trained as climbers. Both are hardy to USDA Zone 3. A newer cultivar named 'Ramblin' Red' has 6-to 10-foot-long canes and is also rated as Zone 3 hardy. These may be good replacements for your current roses.
Q. Late last summer the stems of my perennial sunflower were suddenly coated with red aphids. Do the aphids do a lot of damage? How can I control them organically?
A Aphids, also known as plant lice, are tiny, soft-bodied insects that use their drinking straw-like mouth parts to pierce plants and suck their juices. There are many different species of aphids, ranging from green to brown and red in color. Some attack a wide range of plants, while others are more selective.
Aphids can cause poor growth on plants, and they can also move viruses from plant to plant as they feed. If you notice a heavy infestation of aphids on a particular plant it's worth trying to reduce the aphid population.
Lady beetles (ladybugs) and other beneficial insects often do a good job of eating aphids and reducing their numbers. You can encourage beneficial insects by limiting or avoiding pesticide use and growing a wide range of plants in your yard.
Unfortunately, there's not always a lady beetle gang available when you need one. So try reducing the number of aphids yourself by using a spray attachment on a hose and blasting the aphids with water. Move around the plant to reach all sides of the stems. Repeat this daily as needed. Most of the aphids that are knocked off will not return.
If you're not squeamish, another good way to reduce the aphid population is to grasp the stem with your fingers and run your hand up the stem, smashing aphids as you go. If aphid infestations are heavy and persistent, you may want to try spraying with insecticidal soap.
Nancy Rose is a horticulturist, writer and photographer. To ask her a gardening question, call 612-673-9073 and leave a message. She will answer questions in this column only.