August Gardening By the Month

    “Effort is only troublesome when you are bored.” – Christopher Lloyd


(Heat-loving Bougainvillea will give you color all through the hottest of days.)


lawnmower-384589_6401st WEEK:

Mow lawns weekly (at least every other week if we are in a drought situation), you should be removing no more than 1/3 of grass blade height and leave the shredded clippings on the lawn. Both lawn and soil will benefit. Mowing your lawn often will help prevent weed seeds from germinating and the current weeds from maturing/reblooming. Vary direction of mowing to avoid developing a grain (blades growing/leaning in one direction) to your lawn. – LR

Test sprinkler output with a shallow container such as tupperware or a cake pan. Run the sprinkler for 15 minutes and measure the amount of water collected. The goal is to apply 1/2 to 3/4″ per week to sunny areas and 1/2 to 3/4″ in shaded areas for most lawn grasses to maintain root system health (with 100 degree days it is hard and wasteful to keep grass green), subtract if we receive any rain.

Work some compost into the soil around your perennials so that the nutrients can be released slowly as the compost decomposes.

Water raised beds and plantings weekly (according to rainfall, soil & plant conditions). Make sure you keep the top 6-8 inches of soil moist so that the feeder roots can pick up nourishment and water. Container roses and plants should be watered probably every other day if they are in all sun. Use the “old moisture meter”. . . your finger, to check the soil dampness. Adding extra fertilizer to container plants will not help bloom and may cause problems. When it is 100 degrees day after day, many plants will not bloom. Keep them watered and be patient for better conditions to come in late summer and early fall.

If spring and early summer produced moist, relatively cool weather, it may encourage rust fungus on peaches and plums. If so, treat with wettable sulfur or a labeled copper fungicide so the plant does not defoliate.

July/August is usually dry in San Antonio and vinca prosper. You may observe the Vinca, or Periwinkles are “melting” because of aerial phytophthora, a fungal disease. There is no fungal treatment. Discard infected plants. Water plants at ground level and avoid splashing water on the foliage. Use of mulch helps greatly.

Use the intense heat and sunny days to solarize the vegetable garden by applying clear plastic over tilled soil.

Order wildflower seeds for planting in September and October.

Add compost to the vegetable gardens before planting tomatoes, peppers, okra and southern peas this month. Spread 2 inches of compost and till to a depth of 6 to 8 inches.

Harvest okra every two days to maintain a crop of tender pods. Discard large, tough pods.

If part of your garden is infested with NEMATODES, forgo a fall crop of vegetables in favor of African or American marigolds. The marigolds are beautiful, they will make for a great fall showing, and will help to reduce population of root-damaging pests. Buy them as sturdy transplants without blooms. Plant the flowers every 8 to 12 inches.

July/August is an ideal time to seed buffalo grass and Bermuda when water is available. Plant around August 20th  for proper lawn establishment time.

If you must put down sod now, water as you lay the sod. A delay as short as 2 to 3 hours in watering could result in dormant grass. – CF

Perennial plants should be cut back during the stress of the hot days. Allowing leggy, old growth to remain is doing a disservice to them, as this old growth uses up moisture. If the plant is showing new growth at it’s base, the plant should be cut back to that point and fertilized. If the plant is not showing new growth, cut back by only a 1/3 the height. Mints, as an example, should be cut back to only several inches in height. The plants (all) should be mulched to conserve moisture and ensure sturdy growth.

Sheer back bougainvillea a bit to prepare them for an even better fall bloom.

Tomato, eggplant and pepper plants can be transplanted into the fall garden now, but the tender plants will need protection from scorching (2-5pm) sunlight and pests. Use burlap, cardboard or special fabric products designed to provide shade for the young plants in the garden. You will probably need to continue this practice into the 3rd week of August.

Many trees and shrubs are dropping yellow leaves in a natural response to normal heat and dry conditions. – EO

Apply Copperas or Hi Yield Iron Plus to landscape and garden plants showing iron deficiency. Use iron products carefully because they will stain sidewalks and brick. Only apply this early in the day or later n the evening and water after application.

Plant heat-loving plants such as lantana, bougainvillea, allamanda, hibiscus, mandevilla, copper plant, zinnia, portulaca and salvia.

Look for CHINCH BUGS in St. Augustine grass. Inspect dry, burned-looking grass, irregular-shaped dead areas in the lawn exposed to hot sun. Chinch bugs are about 1/6 of an inch long with a triangular black mark on the wing. Treat with liquid Permethrin, Dylox or Imidacloprid granules for prompt control.


clematis2nd WEEK:

Endure August heat and consider these plants for colorful fall: Marigolds (Discovery Gold & Discovery Yellow), Zinnias, Celosias (Cockscombs), Joseph’s Coat, Mexican Bush sage (Salvia leucantha), Texas aster, Chrysanthemums (garden-type);\, Spider lilies (reds); Belladonna lilies; Fall crocus (Sternbergia lutea); Sweet autumn clematis; Coral vine or Queen’s wreath. Use mulch over the root system.

Scale insects on euonymus, hollies and other shrubs can be controlled with horticultural oil. Follow label instructions and make sure to only spray very early in the day or late in the evening to prevent scorching your plants.

Don’t let your fall garden transplants wilt; keep them watered and mulched to establish vigorous root systems. Mulch not only to conserve water, but also to keep the roots of plants cool and to reduce weeds around trees, shrubs and in flower beds.

Last chance to plant fall tomato varieties. You might want to provide some shade to tomatoes planted now. Covering the upper half of tomato cages with Grow-Web can help the tomatoes survive a hot August.

Harvest some of your Southern peas in the green stage. Use them as you would green beans. You don’t have to shell them.

Pinch shoot tips on Mums and Asters.

Cut back ‘Texas Gold’ columbines if they are looking ratty. They will put on new foliage next month.

If your pecan trees are loaded with nuts, one deep watering per month in the absence of rain will help fill out the nuts. The squirrels will thank you.

Magnolias and other trees will drop their leaves because of the heat. Fertilizer will not help and may increase the problem. Water deeply every 2 weeks to slow leaf drop. – CF

Trim lantana and verbena with a manual or mechanical hedge trimmer for consistent blooms. Unhealthy, shredded stems result if you use a wed whacker.

Southern peas, pumpkin and winter squash seeds can be planted now for harvest in fall. – EO

Look for APHIDS on crape myrtles and treat with an insecticide. If left untreated, the honeydew from the aphids will cause black sooty mold to develop. – LR


caladiumsmanysized3rd WEEK:

Caladiums need plenty of water during drought-like conditions to remain active and lush until fall. Also apply 1/3 to 1/2 lbs. of a 21-0-0 fertilizer per sq. ft. of caladium bed. Water in thoroughly. – EO

Even if you see pansies for sale, please resist; they should not be planted until mid-October.

Bougainvillea are spectacular patio plants. Place in full sun, water only when the soil dries, feed every 2 weeks with 30-10-10 Miracid, let them get rootbound and prune the tips to encourage blooms.

Garden in the morning or in the evening when it is cool. Drink plenty of fluids and wear a hat. Gardening should be fun and not a threat to your health.

Control WEBWORMS with Bt, Spinosad, malathion or Sevin or spray opened webs with Orthene, Pipenyl or Thuricide spray. You can control by piercing the webbing with a pole to let wasps and other predatory insects in if infestation is not too great. Pre-spraying with a little household amonia will dissolve the web nicely to provide an inlet to the predatory insects.

STINK BUGS can be killed with malathion or carbaryl (Sevin). They are prone to attacking vegetables with an unusual ferocity when spring and summer conditions are favorable.

Recognize SPIDER MITES by the dusty, speckled look of the foliage and small webs. Control them with frequent water sprays or Bonide Systemic Insecticide, Pyrethrin and/or Spinosad.

Languishing spring-blooming perennials may be cut back and divided. Replant immediately and water them in. – CF

This is a good time to plant windmill palm, Mexican fan palm and sabal palm in the landscape. ( * If we are still locked in a dry spell withhold transplanting for a week or two.*)

Trim leggy petunias and impatiens to encourage new blooms.

Plant beans, lima beans, cucumbers, sweet corn and black-eyed peas for the fall harvest.

Trim cherry sage (Salvia greggii) and mealy blue sage (Salvia farinacea) for more blooms. Cut spent blooms and a few inches of stems.

Apply borer-prevention spray to trunks of fruit trees such as peaches, plums and other stone fruit. BORERS create holes in an irregular pattern on trunks and sometimes on branches. If the holes appear in a straight line on the tree trunk, woodpeckers are the culprit.

Now is a good time to choose crape myrtles for your landscape. They are blooming, so you can be certain of the color of the blooms. – LR

Fertilize bedding plants with long-lasting slow-release granular fertilizer.

Consider replacing larger areas of your lawn with low-water use plantings. – DP


mandevilla pinksized4th WEEK:

Cooler temperatures – in the low 90’s, as opposed to over 100 – will prompt blooms on hibiscus, lantana, mandevilla, allamanda, bougainvillea and other warm-weather plants. Don’t forget to fertilize with granular fertilizer on soil surface and 30-10-10 Miracid (2-3 times a month at 1Tbsp per gallon) and water in thoroughly.

Start sowing flowering winter annuals, such as Alyssum, Calendula, Larkspur, Poppy and Stock.

Cut back mallow hibiscus plants to 12-18 inches to encourage a second bloom this fall.

Pittosporum may be showing dieback symptoms. In some cases, the problem is caused by a previous winter’s freeze. Recognize freeze damage by cracked bark at the base of the plant. Prune the dead wood out. If undamaged wood remains, the plants may fill in. If pittosporum leaves turn brown, make sure water is penetrating to the roots. Aerate with a turning fork and water deeply.

Leaves may be falling from many trees (especially trees planted in the spring ) as the plants adjust leaf load between a cool, wet spring and a hot, dry summer. It is normal and doesn’t require special treatment. Fungicides aren’t necessary. Also you may find several small, dead areas and broken branches in shade trees. Drought, squirrels and storms with turbulent winds are the culprits.

Tomatoes planted in the past few weeks may not have grown much with excessive heat. Mulch the plants and keep them watered so the roots will be established and plants can grow when temperatures fall in September. With rains and cooler weather, the fall vegetables should be starting shortly.

Mulches are essential to keep the soil cool. conserve water and reduce weeds. Replenish mulch this week. Consider pine bark mulch, pecan mulch or cedar mulch for a functional but also more decorative look. – CF

Pecan trees may drop pecans in response to the heat and extended dry weather. Water trees deeply out at drip line, once a month.

Include Mari-mum marigolds and shasta daisy transplants in the landscape for bright blooms through October.

Continue to protect young vegetable transplants from scorching afternoon sun.

LEAF ROLLERS attacking cannas leave a horizontal line of holes on the leaves. Control the pests with Bacillus thuringiensis (Bt), Thuricide and/or Captain Jack’s Spinosad.

Prune autumn sage to encourage a fall bloom.

Develop a landscape plan now so you can take advantage of autumn planting weather.

Keep lawn mower blades sharp. Jagged cuts on grass blades are entry points for disease.

For best selection, order bulbs from catalogs now.

Fertilize flowering plants. Use a foliar spray to give leaves a boost. Apply in the morning or evening to prevent burning. – LR

Prune summer-blooming shrubs and vines as they finish flowering.

Plan on replacing some of your turf area with pervious ground covers or perennials.

Clean up iris beds and thin out clumps if crowded. They can be transplanted and divided from now until October. – DP

Many thanks to my contributors:

CF – Calvin Finch, Bexar Co. extension agent for horticulture, Texas Agricultural Extension Service (courtesy S.A. Express-News)

EW – Ed Ware, Nurseryman, Master Gardener, Teacher

EO – Edna Ortiz, Bexar Co. extension agent for horticulture, Texas Agricultural Extension Service (courtesy S.A. Express-News)

LR – Lynn Rawe, Bexar Co. extension agent for horticulture (visit their website @, Texas Agricultural Extension Service (courtesy S.A. Express-News)

DP – Diane Pfeil, Bexar County extension associate for horticulture, Texas Cooperative Extension (courtesy S.A. Express-News)

HW – Howard Walters, the Rambling Rosarian

AJW – A.J. “Pop” Warner, from his book “A Year In The Rose Garden”

NS – Neil Sperry, Texas horticulturalist, Publisher “Neil Sperry’s GARDENS”, visit his web site @

HG – John Howard Garrett, aka the “Dirt Doctor”.

THMag – Texas Highway Magazine

JG & TG – Joe Graedon and Teresa Graedon, Ph.D.; The People’s Pharmacy, courtesy S.A. Express-News