Watering Tomatoes: Help for the Perplexed

QUESTION: In a recent article about growing tomatoes, there was mention of proper watering. I would like to know what constitutes proper watering of tomatoes.

--F.D., Oxnard

ANSWER: It’s a tricky topic. How often and how long to water varies greatly with the type of soil and climate. Near the coast where you live, and where I garden, you can water tomatoes in the ground less than once a week.

I sometimes go two weeks between watering my tomatoes if the weather is mild. But--and this is important--I let the water trickle into the 2-foot-wide watering basin around each tomato for about 20 minutes, so it soaks deep into the soil.

If you remembered to plant the tomato seedlings deep (3 to 4 inches deeper than they were in the pot), they are going to be deep-rooted, able to tap moisture several feet below ground.

My experience is that tomatoes produce better kept a tad on the dry side; that is, the soil surface dries between irrigations, though underground the soil is still moist. Get the soil wet, then let it become too dry and you bring on blossom-end rot, so don’t overdo it.

On the other side of town, in hot Altadena, Janie Malloy, who operates Home Grown, must water more often, up to three times a week in summer.

Because this is her business, she keeps accurate tabs, and the results are interesting. Watering with drip emitters that deliver one-half gallon every hour, she finds that she must run the drip for two hours so every plant gets a gallon of water during each irrigation. In spring, she must turn on the drip twice a week, and in summer, when temperatures go above 90 degrees, she waters three times a week. Both of us mulch our plants to conserve water, cool the soil and cut down on disease.

If you want to try another method of watering, Robert Ambrose, publisher of the Tomato Club Newsletter (P.O. Box 418, Bogota, NJ 07603, [201] 488-2231), has noticed that many experienced home-growers water tomatoes from below.

At planting time, they insert a piece of 2-inch PVC pipe, or even a coffee can with holes in the bottom, so the water is delivered to the roots about a foot underground and the soil surface never gets wet. The May/June issue has a particularly clever method of doing this, using a 2-foot length of 2-inch PVC pipe, with 1 foot buried and the rest sticking out above ground. An upside-down gallon-sized plastic milk carton (with a small hole in the bottom to let air in as water runs out) is inserted into this when watering.

Whatever method you use, one thing is for sure--water deeply. Trying to water by standing there with one’s finger clamped over the hose definitely does not make for happy tomatoes.

Budworms Definitely Not His Buddies

Q: My burning question has to do with geranium budworms. They have chewed up leaves on my geraniums and buds that did not materialize into flowers. I keep getting new geraniums and they keep eating them. What can a person do about a moth that comes in the night and lays eggs?

--C.D., Los Angeles

A: You need to break the cycle, according to Louis Andrade of Grand View Geranium Gardens, the largest grower (wholesale only) in the West. There, they mostly use liquid Bt (Acillus thuringiensis), a nonpoisonous, biological control (Safer is one manufacturer), and apply it on a regular basis because it works best on larva when they are young.

To break the egg-to-adult cycle, Andrade suggests first spraying the damaged plants with a pyrethrin-based spray or Orthene to kill large adult worms, then--a few days later--spraying several times in a row with the Bt. He suggests spraying three times with each spray, three days apart. From then on, spray with Bt once every couple of weeks to prevent new budworms. When you think you have the problem under control, you might want to stop spraying, but keep an eye out for new damage and apply Bt at the first sign.

Andrade doesn’t use Bt straight out of the bottle. To a gallon of water, he first adds a couple of liquid ounces of white vinegar, “to sweeten” or soften the water. Then he adds the Bt, plus a couple of drops of household detergent, which makes the water “wetter” so the spray sticks better to the foliage. Use this solution to spray the tops of the leaves and flower buds early in the morning or in the early evening. That would be the nearly nonchemical approach.

Orthene, a systemic insecticide that gets into plant tissue and, thus, into the flower buds where worms secret themselves, would be the best chemical approach, but don’t use Orthene near anything edible and follow label directions carefully.

Avocado Trees Can Be Radically Trimmed

Q: At what time of year can a ‘Fuerte’ avocado tree can be pruned? It is 18 to 20 years old and quite large.

P.P., Los Alamitos

A: Prune avocados after the harvest, which in the case of ‘Fuerte’ would be right about now since they ripen November to April. Daniel Hagillih, the superintendent at the UC South Coast Research and Extension Center, suggests taking about one-third of the growth off to let more light into the tree. Letting light inside greatly increases production.

You can also prune them quite drastically. Often this is a good idea, so future fruit ripens closer to the ground. After radical pruning, be sure to protect the limbs and trunk, suddenly exposed to strong sunlight, with ordinary white latex paint to fend off sunburn.

Julie Frink, a member of the California Rare Fruit Growers (based at the Fullerton Arboretum) and a volunteer at the South Coast center, says that people don’t realize that avocados can “really take a whacking,” more than most fruit trees. In the groves at the center, they often cut tall, old trees (of about the same age as yours) with a trunk diameter of a foot or more, down to stumps about 4 feet tall, then let them re-sprout. That’s radical pruning! Sometimes they graft better varieties to the new growth, but the real reason is to get the fruit back down to picking height.

Questions should be sent to “Garden Q&A;” in care of the Real Estate section, Los Angeles Times, Times Mirror Square, Los Angeles, CA 90053. Please include your address and telephone number. Questions cannot be answered individually.