How to irrigate St. Augustine grass
Q: To keep my St. Augustine grass alive, how often does it need to be irrigated?
A: In a test conducted in San Antonio by the Turf grass Producers of Texas, San Antonio Water System and Texas A&M University, St. Augustine on 4 inches of soil (and all other grasses) died after 60 days of no water. All the grasses on 12 inches of soil recovered after varying degrees of time.
In the same test, St. Augustine did well after 2 weeks of no rain or irrigation. The best answer seems to be water every 2 weeks if you can, but the grass will survive much longer if it is on deep soil.
Q: Can we collect the larkspur seed to plant it at other locations in the garden?
A: Yes, pick the whole plant once it turns brown, but before the seed pods burst. Put the plants in a large paper sack so that when the seed drops from the pods, it is collected in the sack. Next fall, spread it over the surface of the soil at the new planting site.
Q: We love the Tycoon tomatoes. Is the new Rodeo tomato, Valley Cat, supposed to be as good?
A: Each year a new tomato is selected to be the Rodeo tomato after testing from available varieties. It is sold as a fund-raiser for the San Antonio youth gardening effort. The selections are usually excellent producers for the Central Texas area, but all are different, and everyone has their favorite variety.
Valley Cat is reported to have a similar lineage to Tycoon but has more types of nematodes resistance.
Q: What are some foundation shrubs from which to select? Are any deer proof?
A: Dwarf yaupon holly, dwarf Chinese holly, viburnum sandankwa, and Compact nandina all work well planted around the house. The deer do not like any of them but are most likely to eat nandina.
Q: Our Texas mountain laurel has a little caterpillar that is eating the new foliage. What is it called and how do we control it?
A: The caterpillar is the genista caterpillar. Spinosad and Bt are organic controls that will control it. Sevin and malathion also work well. Unless damage is severe, however, they don’t need to be controlled. Leave them to the birds and the predatory wasps.
Q: Our irrigation contractor was not very encouraging when we suggested that we wanted to replace sprinkler zones with drip irrigation. He said it is not as efficient as people say and it is hard to maintain. What do you say?
A: I say, “Get a new irrigation contractor.” The answer you were given is the answer that unskilled contractors with drip irrigation used to say. Drip irrigation is much more efficient than sprinkler irrigation, and a well-constructed drip system is simpler to maintain then a sprinkler system. The good news is that most irrigation contractors can work with both systems now.
Q: Tell us again what were the mid-day onion varieties that we can plant now and still raise some decent onions.
A: Plant candy (yellow), red candy apple (red), or superstar (white) as quickly as possible.
Q: My nursery has Dreamland zinnias. Are they a good variety to plant? Can we plant them now?
A: Yes, Dreamland is a good variety with colorful, large rounded blooms. The plants resist powdery mildew the best of any varieties I have grown in this area. Plant them now through September.
Q: We blundered and already fertilized our lawn. Is it a major blunder? What will happen?
A: Early lawn fertilization results in wasted nitrogen because the lawn grass is not capable of using the nutrients until the roots and top are growing actively. Wait until you have mowed real grass twice to fertilize. If you used slow-release lawn fertilizer, at least half of the nitrogen will still be available to the lawn later in the spring and summer.
Calvin Finch is a horticulturist and the director of the Water Conservation and Technology Center at Texas A&M-San Antonio. Hear him on “Gardening South Texas” on KLUP 930 AM radio Saturdays noon to 2 p.m., and 1-3 p.m. Sundays. Or, email him at email@example.com.