Alameda Sun, Thursday, March 9, 2023
by Holly Johnson
Tomatoes are nearly everyone’s favorite food to grow for themselves. Here are some tips for successful tomatoes in Alameda, collected from Alameda Backyard Growers’ resources, local gardening experts, and notes from a past presentation by Evan Krokowski, the former farm coordinator for Farm2Market.
Preparing the Soil
Pick the sunniest, warmest spot in the garden. Extra points if there are adjacent pavers or a sidewalk to keep the soil even warmer. If the rainy winter waylaid plans for cover crops and working in amendments, try to add 4 or 5 inches of well-aged manure or compost to the top foot of soil, water well, and wait one week before planting.
When container-growing a tomato plant, a black plastic pot at least 18 inches deep can be a great idea, keeping the soil warm even as the fog rolls in. But hours of hot sun can be brutal on a plant in a black pot. In the event of occasional heat waves, be prepared to move them into light shade, especially by mid-to-late-afternoon.
Choosing Varieties
With Alameda’s breezy and cool summers, varieties with relatively fewer days-to-maturity may be safest. For container gardening, try a compact plant or one developed for containers. Alamedans have long been advised to stick to cherry or “saladette”-sized tomato varieties for the best success, but even a beefsteak variety may yield a tasty crop if its location is chosen based on the most continuously warmed soil.
Planting
April is a great time to plant tomatoes. Dig a deep hole. Roots will form along the buried portion of the stem, so it’s good to bury the plant up to its first leaves, even removing the lowest leaves and bury the stem from which the leaves were removed if the plant is big enough. Leave a few feet between plants to improve air circulation.
Make sure the soil is moist when planting and keep the soil moist for 3 to 4 weeks. After that, cut back the moisture so that the 2 to 3 top inches of the soil dries out before watering. But don’t let the tomato roots dry completely out before watering — inconsistent moisture causes problems in the fruits. A mulch of dark chips will help keep the soil warm as well as keep moisture in and weeds down.
Caring for Plants
Water young plants regularly, ensuring that the water goes deep. The surface should dry out before watering again. If tomato leaves droop, it means they need more water. Avoid getting the leaves wet. Established plants taller than 1 to 2 feet need less frequent watering. Once fruit begins to mature and starts to turn red, water only when leaves are drooping for a richer flavor.
Prune foliage on established plants to allow more sunlight exposure and pinch off suckers that grow where branches meet the main stem to save energy for the fruit producing branches.
Fertilize 2 or 3 times early in the season but not after fruit begins to set. Weekly applications of a diluted fish emulsion to foliage and soil will stimulate healthy growth
Avoiding Maladies
The fungi Verticillium or Fusarium cause plants to wilt, and there is no way to save affected plants. The best way to manage the problem is by planting resistant varieties the next year. If a variety is resistant to verticillium, it will be labeled V; for fusarium resistance, the label is F (sometimes followed by a number). In Alameda, many of us need varieties that will grow without a lot of heat, meaning with days-to-maturity ratings of 55 to 75. Finding both disease resistance and low days-to-maturity in a single variety can require some research! To try to avoid getting one of these wilts, rotate crops, so that you don’t grow tomatoes or other plants susceptible to the wilts in one place every year, to avoid buildup of the fungus in the soil.
Powdery Mildew shows up as white powdery spots on both surfaces of leaves, or sometimes just yellow patches on leaves. Alameda gardens can be very susceptible to powdery mildew, because moderate temperatures (60° to 80°F) and shade encourages the disease. Practice prevention by planting resistant varieties where available, planting in full sun, pruning or staking to provide good air circulation, and avoiding excess fertilizer — slow-release fertilizer is good. And keep a close eye, to pounce on any early signs quickly. Some gardeners have had success with spraying affected plants with diluted milk as soon as the mildew was apparent and repeated often.
The Hornworm moths lay single eggs on the tomato leaves. When the caterpillars hatch, they munch on tomato leaves and fruit. The caterpillars get large, but their color and stripy pattern make them remarkably hard to see. They can be managed by picking them off and cutting them in two. Rotating crops and breaking up and turning over the soil will destroy pupae in the soil and help prevent repeating the hornworm life cycle the following year. Inspect the undersides of leaves for hornworms and aphids, as well.
Plants with blossom end rot have small, light brown spots at the blossom end of immature fruit. As the fruit ripens, the spot expands into a dark leathery lesion. To reduce the problem, monitor soil moisture, add compost to increase the soil’s water-holding capacity. Use mulch to reduce evaporation.
Tomatoes with Sunscald have tan to light brown leathery patches on the side of the fruit that is exposed to the sun. It’s caused by overexposure to the hot sun. When we have warm days, it can definitely be an issue in Alameda if you have a nice sunny tomato patch. To prevent sunscald, provide partial shade during the hours of most intense sunlight. Keep plants vigorous with appropriate fertilizer and water to produce an adequate leaf cover and avoid too much pruning.
Planning, prevention, and persistence will help Alameda gardeners produce the perfect tomato crop this year!
Holly Johnson is a board member of Alameda Backyard Growers (ABG).
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