Week of March 4, 2002

By Calvin Finch, Conservation Division, Manager, Water Resources & Conservation Dept.,

SAWS, and Horticulturist

MARCH GARDENING

            March is the beginning of warm weather gardening in San Antonio. The last freeze has usually occurred and by mid month nights are warm enough that hot weather plants will thrive.

It is still too early to fertilize the lawn. The soils aren’t warm enough that grass roots are completely active. Wait until the lawn has been mowed twice. Not weeds mowed but St. Augustine, zoysia, Bermuda, or Buffalo grass. That usually occurs in late April or early May. It is still a good time to aerate and top dress the lawn. Use compost for the top dressing, about half an inch deep. It is the best tonic available for a weak lawn.

If summer weeds like sand burs or crabgrass were a problem last year, apply a pre-emergent herbicide early in March. Follow the label instructions closely. Don’t waste the water on the lawn in March. The grass is not active yet and evapotranspiration is so low that little water is used by the lawn. Wait until later in the summer when the lawn really needs irrigation.

            March is the time to plant many of the hot weather flowers. Semperfloren begonias are usually used in the shade but, if they get an early start, they can be planted in the sun. The plants do all their growing when the temperatures are cool and then survive the summer. Use zinnias in the sun. The pansies, cyclamen, snapdragons, dianthus, and other cool weather flowers really make a show in March. Fertilize them with slow release lawn fertilizer, about one cup per 50 sq. ft. of flower bed. Carpet, Laura Bush or Kahuna petunias like cool weather and will last into the summer. Use them to fill open areas in the full sun garden.

            Rose selection is the best in the nurseries now. If you want to produce modern roses to their full potential, they need a raised bed, drip irrigation, weekly insect and fungus sprays, monthly fertilization, and mulch. Old-fashioned roses do not produce flowers as large as modern roses but they are tougher plants. Old-fashioned roses like Mrs. Dudley Cross or butterfly rose will grow in native soil without a regular spray program. Belinda’s Dream is a modern rose with old-fashioned toughness. The old-fashioned roses qualify as xeriscape plants.

In the vegetable garden it is time for green beans, beets, carrots, radishes, and summer squash seeding. Tomato transplants will do well if we have a warm month, but be prepared to replant in April if March is wet and cold. The recommended varieties are Surefire, Merced, Sun Master, Heat Wave, Celebrity, Bingo, Whirlaway, and Carnival.

The broccoli and spinach may produce until late April. Keep the buds and leaves harvested. Onions require heavy fertilization. Use a cup of slow release lawn fertilizer per eight feet of row, side dressed two inches from the stem. If you planted them thick, harvest all the onions necessary to allow four to six inches between the remaining plants. The bulbs need plenty of room in April

            Control caterpillars on broccoli, Texas mountain laurels, and other plants with Bt products such as Dipel, Bio-worm Control, and Thuricide. Aphids may show up on any actively growing plant. Organic growers can try to control them with water spray or insecticidal soap. Orthene is a sure kill on ornamental plants.

Fire ants will become more active as the temperatures warm. Use baits like Amdro for efficient control over large areas. Contact insecticides can be used for mounds threatening human or pet activity.

The American goldfinches will continue to feed at your thistle feeders in March and even April. They will begin to look like wild canaries instead of drab finches as they grow their breeding plumage. Hummingbirds and purple martins return this month. Put the sugar water feeders and martin houses up to attract the interesting species.

Enjoy the mild weather to work in the yard. It is an ideal time to build patios, fences, and raised beds. Trees and shrubs can be planted. Conserve water. March is usually a wet month and the plants do not need supplemental irrigation in most cases.