Regional Gardening Reports :: National Gardening Association

In the Garden:
Lower South
July, 2010
Regional Report

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Some late summer care can help prepare these roses for a spectacular fall blooming season.

Late Summer Rose Care

By late summer the weeks of brutal heat can really take a toll on our roses and other landscape plants. However the good news is that the fall season is on the way and with it comes the second great blooming season for roses. Provide your plants some TLC now and they'll reward you with a bountiful bloom show when cooler temperatures return in the fall.

Proper watering is the single most important thing that you can do to keep roses healthy and productive in the summer. Roses need moderately moist soil but detest soggy soil conditions. A good soaking once a week is usually adequate, but depending on the soil conditions and summer temperatures, a little more often may be helpful.

Apply water to the soil surface throughout the area beneath and just beyond the branch spread of the bush. Spraying the foliage with sprinkler irrigation should be avoided if possible as the frequent wetting only increases the incidence of leaf diseases.

Periodic fertilizing is helpful to maintain good vigor and repeat blooming. To promote good vigor and foliage development choose a fertilizer high in nitrogen. A typical lawn fertilizer with a ratio of nutrients of 3-1-2 or 4-1-2 works fine. Leaves are needed to produce carbohydrates which result in good bloom production. Thus promoting good vigor now will set the plant up for a productive bloom season to come.

Sprinkle fertilizer evenly throughout a circular area 3 feet out from the bush in all directions. Apply about 1/2 cup if the product contains 6 to 9 percent nitrogen, the first number on the bag, and 1/4 cup of fertilizer per bush if it contains 15 to 21 percent nitrogen. Slow release fertilizers can be applied at higher rates since they don't tend to burn roots. It is very important to give the plants a thorough soaking after fertilizing to move the nutrients down into the soil.

Don't fertilize drought stressed roses. First provide them a good irrigation and after they have had a week or so to recover, then apply a little fertilizer and water it in well.

While most pruning is done in late winter, rose varieties that continue to bloom on through the growing season will benefit from some additional clipping in mid to late August. Start by removing any dead branches in the plants. Trim them out with sharp pruners to just below the dead area. Also remove any spent blooms from the plant.

If you have any rose varieties that bloom only in the spring each year, no additional pruning should be done to those plants at this time of the year. These spring-only bloomers set their bloom buds for next year in late summer and early fall, so pruning can reduce next year bloom production.

Hybrid teas are the long stemmed types grown for cut flowers. They typically produce one bloom per long bloom shoot. Grandifloras are also vigorous growers but produce a cluster of blooms at the end of their shoots. For both types trim out the small brushy growth leaving the larger shoots about "pencil sized" or larger. Then cut the rose bush back to about "waist high".

Floribunda roses produce clusters of blooms repeatedly throughout the season on bushes that are more shrubby in growth habit. You can prune them with a similar technique as was described above with the exception of leaving branches somewhat smaller than pencil sized when removing any small, brushy growth.

Shrub type roses are generally just sheared back by about one third for simplicity's sake. I generally follow this up with a little hand pruner work to cut out any broken, hanging branches left after shearing.

In addition to fertilizing and watering roses, it is important to protect the foliage from pest and diseases. The two most common rose diseases here in the lower south are black spot and powdery mildew. Both are fungal infections that destroy foliage. The best way to prevent them is to plant naturally resistant or at least tolerant cultivars.

If you already have a susceptible variety it will be necessary to provide protective sprays periodically to prevent these diseases from getting the upper hand. The key is to not wait too late to spray. Sprays, whether organic or synthetic, work best as a preventative rather than an attempt to cure an already serious disease problem.

The two most common rose pests are spider mites and aphids. Spider mites feed beneath the foliage causing it to turn a speckled bronze color and often leave a fine webbing on the plant foliage and twigs. Aphids suck juices from the tender shoots and foliage.

Mites and aphids can be controlled by strong sprays of water directed upward from beneath the plant, or by insecticidal soap sprays.

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