Bexar County Master Gardeners » "Have you volunteered today?"

Gardening Chores: August

August, the hottest and driest month in Texas, is deep summer in San Antonio. Good xeriscape plants will make it through the month without supplemental watering; others will need conscientious watering to stay prosperous. August is the month when good mulching makes a major difference.

This is the month to evaluate what’s happening in the yard and gardens…time to plan for next season or next year. 

Generally no fertilizing or planting is done during this month. 

Birds and Wildlife 

 Move the hummingbird feeders to the patio with firebush, salvia, hibiscus and dwarf Chinese trumpet creeper.

 Change your sugar water every week. Pour the old liquid in a shallow dish for the butterflies.

 Keep birdbaths full.


 It‘s time to plant mari-mums. Get transplants that haven‘t bloomed yet.

 Seed zinnias and sunflowers this month.

 Lantanas, firebush, purslane, portulaca and periwinkles are prospering in the heat.

 Watch for spider mites. If you find them, control with a miticide.

 Maintain bloom on the crape myrtles and vitex by removing (deadheading) the spent blooms. You‘ll get 2-3 times the number of blooms the next time around.

 Lantana bloom can be rejuvenated with a string trimmer once per month. Take about 6 inches off the plant to rejuvenate it.

 Bougainvillea loves the Texas summer heat. If they‘re root bound in the pot, even better. Wait until they just start to wilt before watering—this could be every day depending on the pot and the plant.

 Maintain the mulch layer at 2-3 inches to help avoid soil moisture loss.

 Prune the roses back, but not as heavily as you did last spring. Apply a good rose food and water it in well. Stand back and wait for the fall blush of bloom. If you have hybrid

tea roses, maintain or resume your spraying regimen for black spot and insects.

 Trim back overgrown or leggy spring-planted annuals such as petunias and impatiens to encourage new flushes of growth and renewed flower production when the weather cools.

 Add two pounds of a slow release fertilizer such as 19-5-9 per 100 square feet after pruning.

 To prevent leaf-fungal problems, water only when the leaves will have time to dry off before nightfall. Better yet, water only the soil and not the leaves.

 Get out the catalogues for spring and summer bulbs and start dreaming.

 Thin spring-blooming bulbs. Give half to friends, neighbors, and family and re-plant the other half.

Fruits and Nuts 

 For full production, pecan trees need 1 inch of water per week over the entire root area. Fruit trees can be maintained with less after the harvest but also require 1 inch per week for fall production.

 Apply borer spray to the peach trees this month. For a good crop next year, you want the leaves to last until November so watch for web worms and rust. Use Bt or Spinosad on the web worms and a good fungicide for the rust.

 Early apples are ready for harvest.

 Prune the spent canes from the blackberries.

 After harvest, a deep watering on the peach and plum trees once per month will help develop a good crop next spring.


 Moy Grande hibiscus produces 12-inch blooms in full sun.

 Gold Star Esparanza produces fragrant yellow flowers clear up until frost.

 If you have Bermuda grass in the flower beds, use Grass-Be-Gone or similar products. If you follow directions, it will kill only the Bermuda grass and not hurt the flowers.

 Stake or support larger-growing plants that have become heavy or are leaning over.

Shade Trees and Shrubs 

 Shade trees can reduce the heat gain in a home by 40-80 percent. Plan now to plant some fast-growing shade trees on the west side of the house later this fall.

 Around here, cotton root rot is stimulated by hot soil temperatures. Cottonwoods, roses, Chinese pistache, sycamore and okra are very susceptible while most native plants are resistant. It kills plants so fast that their leaves are still on the plant. There is no effective treatment although native plants are less susceptible.

 This is the second-best time to prune live oak trees. The oak wilt fungus spores and nitilid beetles are not active in hot or cold weather. Be sure to immediately paint any cuts you make with a latex paint.

 Vigorous-growing shrubs such as pyracantha, photinia, eleagnus, privet or ligustrum may need to be pruned regularly to keep them within bounds.

 If you have scale problems on your shrubs, use light summer oil. Follow the directions on the label.

 If your trees are dropping leaves, it‘s OK. They‘re just adjusting to the water supply and the heat.

 Fall webworms may appear on pecan, mulberry, ash, persimmon, and other trees. The biological spray Bacillus thuringiensis (B.t.) provides control but a new, longer-lasting fungal metabolite is now available. It is an insect nerve agent named Spinosad and sold as Fertilome Borer, Bagworm, Leafminer, and Tent Caterpillar Spray. It is also labeled for use on fireants.

 Windmill palm, Mexican fan palm and Sabal palm are especially well-adapted to this area, and now is a good time to plant them. Palms require warm soil to establish their root systems.

 Mulch, mulch, mulch—2-3 inches deep under all the shrubs, around the trees out to about 5-6 feet, and in the flower beds.

 Remember that newly-planted trees need watering once per week for the whole first season.

Turf Grass 

 In August, all grasses require some water to stay green. Check out the San Antonio Water System‘s web site to find out how much for your grass in your yard. If you have Bermuda grass, zoysia, or buffalo grass, you don‘t need to water…it‘ll just go dormant until it rains again.

 When you see your footprints in the grass, it‘s time to water. Do it early in the morning and water deeply. Shallow watering causes shallow roots which are easy to damage.

 Grub worms eat the roots of grass plants. If you can lift a piece of sod and if you see 3 or more grub worms in a square foot, you‘ve got a problem. Treat with a good pesticide which lists grubs on the label.

 Chinch bugs do their damage in the hottest part of summer in the hottest part of the lawn; i.e., close to the house, driveway, or sidewalks. It looks kind of moth-eaten and doesn‘t respond to watering. Cut the top and bottom out of a coffee can, place it about 1 inch into the soil and fill it with water. If little bugs float to the top in 2-3 minutes, they‘re probably chinch bugs. Treat with a good pesticide and be sure to follow the directions. More is not better.

 There is still time to establish a new lawn, but don‘t wait much longer. If we have an early freeze, it could kill it or at least put a major hurt on it. It might be best to wait until spring.

 Remember when laying new sod; roll the turf to insure good soil-root contact and water thoroughly on a daily basis until the grass is established — in a week or 10 days. Bermuda grass can be seeded (August is the last chance to plant Bermuda grass seed) now; use some of the improved Bermuda grass seed such as Sahara or Cheyenne.



 Early August is the best time to start planting the fall garden. Use transplants for tomatoes and peppers and direct seed corn and beans later in the month. Protect the young transplants from the hot sun with a light fabric like Gro-web or even an old sheer curtain…anything to provide just a little shade.

 Plant pumpkins in early August for Halloween jack-o-lanterns. Be sure to get the 90-day variety.

 Other popular vegetable crops to plant in August for fall production are cucumber, eggplant, lima beans, black-eye peas, peppers, and squash.

 If you‘ve had nematode problems in the veggie beds, now is the time to ―solarize‖ them. Till the soil, wet it down and then place clear plastic over the entire bed. Weight the edges down with soil and let it cook for several weeks. It‘ll basically pasteurize the top few inches of the bed.

 Write me at to get the recommended vegetable varieties for the state of Texas. If you live outside the state of Texas, check with your county agricultural extension office.

Print Friendly

Your email is never published or shared. Required fields are marked *