If large, dark, leafy-green rose bushes loaded with blooms are what your after, now is the time to act! The cooler weather of Fall provides ideal growing conditions for roses. But they also need help to grow and bloom to there maximum potential. This help is in the form of pruning and fertilizing.
Pruning is essential to promote new growth. Only on this new growth will flowers be produced. Light pruning will produce the desired results. Plants are allowed to remain 3 to 4 feet in height after pruning.
Select stems pencil-sized or larger and cut them back to an outward facing leaf. Stems thinner than pencil-sized are weak and should be removed. Hidden at the base of the leaf is the dormant bud. Pruning just above this dormant bud will cause it to break (grow) and produce a bloom or spray.
To keep the rose bush open to sun and air, prune just above outward-facing buds to encouraged outward-facing growth. Inward-facing growth results in clogging and crossing of branches. Cut about one-quarter inch above the outward facing buds. Make the cut a slanting one, with the bud on the high side.
Cut back lightly, to produce abundant roses for garden display. Every cut should result in the production of a bloom. Don=t cut too far down the stem. You should remove no more than the outer one-third of the stem. Remove stem portions with Summer-scorched leaves. Also remove dead wood, weak and crossing stems. Heavy pruning will not be necessary until January.
If exhibition blooms are what you desire, look for a cane one-half inch thick or go down the length of the cane until it reaches this size. Again, cut on an angle one-quarter inch above an outward facing leaf. These large cuts should be sealed with Elmer=s glue or another type of carpenter=s glue to prevent cane boring insects from getting into the cut end. On exhibition roses it may be necessary to stake the new stem growth to keep it straight.
Summer rains and constant irrigation has washed nutrients out of the soil, especially nitrogen. As a result roses look a little yellow. They also may be lacking in iron. To correct these deficiencies apply ammonium phosphate or a specially formulated rose fertilizer. One pound of fertilizer per 100 square feet of rose bed area should be adequate. You may also fertilize your rose bushes individually, using one-half cup of fertilizer per bush. Scratch it in to the top layer of soil and water it in.
If young leaves are yellow with green veins, an iron deficiency is present. To correct this deficiency apply chelated iron according to label directions. Chelated iron should diluted in water and soaked into the soil. For quicker results chelated iron may also be sprayed on leaves for a rapid green-up. Use only chelated forms of iron as they are the only types that will preform in our alkaline desert soils.
Insect pests such as aphids may reappear on roses in October. Keep a look out for these small, soft-bodied green bugs. They are attracted to new growth, and their sucking habit of feeding curls young leaves and causes a sticky substance, called honeydew, to develop. Aphids can be controlled by spraying the leaves with a strong jet of water from a hose-end attachment. Soap sprays are also effective at controlling aphids.
Finally, reduce the frequency of irrigation as we go later into Fall and the temperatures continue to cool. Over-watering in late Fall and Winter can leach out nutrients and encourage root rot fungus diseases.
Written by John Begeman, College of Agriculture, the University of Arizona, 520-626-5161.
Material originally appeared in Arizona Daily Star gardening column, on October 1, 2000.
