By Calvin R. Finch
Guest Columnist

Heat and water are the gardening topics of the month again in August.

Irrigate enough to keep your lawns and plants alive, but forego perfection. A perfectly green lawn will result in unacceptable high water use and a high water bill.

Irrigate the lawn once per week at the most and only water trees and shrubs when they need it. Newly planted shrubs and trees may take water every week, but established trees probably do not need any irrigation.

Water blooming shrubs like old-fashioned roses and lantanas once per month for best blooms. Esperanza and Poinciana do well without irrigation. Vegetables, containers and annual flowers may require water several times per week.

In the vegetable garden, plant fall tomatoes early in the month. Surefire is the most reliable autumn tomato for fall production. The plants produce a tennis-ball-sized fruit and always seem to beat the first freeze. Unfortunately, there will only be a limited number on the market. Solar Fire, Sun Pride, 444, Amelia and Celebrity are also good choices, but do not mature as fast as Surefire.

In the flower garden, large American hybrid marigolds, often called “Marimums” are a good choice for early August planting. Purchase sturdy plants without open blooms so they put some size on before the flowers open.

Plant them close together for major impact. A massed planting of Discovery or a similar large marigold will be showier than garden mums and also bloom for a longer period. Fall is a good time to plant marigolds because as temperatures cool they are less likely to be overcome by spider mites.

Vincas, zinnias, moss roses and purslane can also still be planted. They will last until the cold weather arrives. To minimize water use and heat stroke, be conservative about planting in August. A few showy blooms in containers make a major impact in the landscape without requiring excessive water and work.

In addition to those flowers, consider firebush and pentas. They have showy blooms that attract butterflies and hummingbirds, and do very well in containers. The firebush come back every year and the pentas have shade-tolerance.

Early August is a good time to lightly prune your hybrid tea roses for the fall flush of growth and bloom. Remove wounded, dead, and diseased wood, and open up the middle with your pruning.

It is also time to begin your spray program. Use acephate and Funginex. Organic gardeners can try Spinosad, sulfur and Rose Defense. Add one cup of 19-5-9 slow release lawn fertilizer per plant and begin your regular irrigation.

The young hummingbirds are off the nest and visiting sugar water feeders. In another month, the migrant birds will begin moving through. Keep the feeders clean and full. Fire ants can be a problem. Move the feeder around to keep ahead of them.

The purple martins left the nest in July. August is a good time to lower and clean the houses. Leave them down until March to minimize their use by starlings and English sparrows.

Keep your bird baths full and clean this month. Water is more important than food during a hot dry period. For a new bird bath, place it at least 6 feet from a bush that could serve as a launching site for cats. Wet birds are particularly vulnerable.

Calvin R. Finch, Ph.D., is a horticulturist and the director of water resources for the San Antonio Water System.