Gardeners Hope For Cooler Days In Late Summer

Daniel Gill, Merrill, Thomas A.  |  8/27/2005 3:00:49 AM

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Get It Growing News For 09/02/05

If we’re lucky, we might have some cooler days this month, since cool fronts often begin to make their way this far south in September. After the long, hot summer, these last scorching days are especially hard to bear for gardeners and their landscapes.

Plants under heat stress are weakened, and we always see an increase in disease and insect problems at the end of the summer.

Keep your eye out for pests such as mealy bugs, aphids, leaf hoppers, scales and whiteflies. Another pest, spider mites, also can be very damaging to a wide variety of plants.

A good low-toxicity pesticide for these pests is a light oil spray such as Sun Spray Ultra-Fine Oil. But while daytime highs are still in the 90s, be sure to spray in the cooler hours before 9 a.m.

Diseases will be particularly bad if we get a lot of rain while it is still hot. Root rots are common during rainy, hot weather. Leaf spots also may show up on many plants, but, in most cases with deciduous plants (those that drop their leaves in fall), it’s really not worth treating this late in the growing season.

While it’s hot, continue to do most of your work in the cooler morning and evening hours – and don’t forget the mosquito repellent.

Important chores to be done this time of year include trimming back overgrown plants, especially bedding plants and tropicals such as lantanas, pentas, impatiens, periwinkles, hibiscuses and many others. They will look better this fall if you do.

But remember it is too late to prune spring-flowering trees and shrubs heavily.

You also should continue weeding (mulch and you won’t have nearly so many), watering (best done in the morning) and grooming plants by picking off faded flowers and trimming unattractive foliage.

If you have received garden catalogs offering spring bulbs, you should make your selections and order soon. We plant most spring-flowering bulbs in October and November. Also check local nurseries for what they have available.

It’s already too late to plant warm-season bedding plants, and it’s too early to plant the cool-season ones, so not much should be added to the flower garden now unless you have some overwhelming necessity for it. If needed, you could still plant transplants of warm-season bedding plants, but we are getting toward the end of their season. Even a bare area would probably best be mulched and held until next month when cool-season annuals could be planted.

Lawn Care

Now also is a time to consider whether you need to take steps to care for your lawn.

You may make a last fertilizer application in early September – although if the lawn has an acceptable color and rate of growth, this fertilization is optional. If you decide to fertilize, you could use any commonly available lawn fertilizer or use an all-purpose formulation following package directions carefully. Apply the fertilizer evenly with a spreader to a freshly mowed lawn and water it in immediately.

You may see information this fall about "winterizing" your lawn. This is meant to prepare the grass for the winter, and increase its hardiness. Under most circumstances, winterizing is optional. If you choose to winterize, make sure the product you use has a very low first number (nitrogen) – not higher than five. The third number in the analysis is the percentage of potassium, the nutrient important in winterizing the lawn, and it should be relatively high.

On another matter related to your lawn, chinch bugs will continue to damage lawns until cooler, moister weather arrives. Look for dead, tan, straw-like areas in sunny, dry locations (along concrete surfaces, between the sidewalk and the street) that get bigger each day. Treat promptly with cyfluthrin, bifenthrin or acephate. Follow label directions carefully.

Prune Roses Now

Roses make vigorous growth during the spring and summer, and a late August or early September pruning of ever-blooming roses is recommended. This pruning is not as severe as the one done in late winter.

First, remove all diseased, dead or damaged canes and the weak canes. Then cut the more vigorous canes of hybrid tea and grandiflora roses back to about 2-3 feet above the ground. Other types of roses, such as antique and landscape roses, are pruned less severely – just enough to shape them the way you desire.

Make your pruning cuts just above a leaf or dormant bud. Also, be sure to clean up all leaves and trimmings from the area and give your roses a light application of fertilizer, following label directions.

Insects and diseases stay active through the fall, so continue to control rose pest problems with timely applications of the proper pesticides. In addition, don’t forget to water well during dry periods, and you should have an excellent crop of flowers in October through November.

Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at A wide range of publications and a variety of other resources are available.


Contact: Dan Gill at (225) 578-2222 or
Editor: Tom Merrill at (225) 578-2263 or

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