Planning for planting

The sun is shining, tomato plants are in the garden centers and your neighbor is bragging about having tomatoes in the ground. Is it time to plant tomatoes?

Resist the temptation. Tomatoes require warm soil and are very sensitive to frost. The optimum growing temperature for tomatoes is between 75 and 95 degrees. Temperatures below 57 degrees will actually delay growth and encourage disease.

Soil temperature is as important as the air temperature. Check your soil temperature in the morning at a two-inch depth for seven consecutive days. The minimum soil temperature for tomato growth is 50 to 55 degrees.

Planting tomato seedlings outdoors before the air and soil temperatures warm up will not help achieve early-fruiting tomatoes. The plants will fail to set blossoms, or they will set and then most likely drop the blossoms. So you can put your tomato plants out early and spend lots of time and effort to protect them from the elements, but seedlings planted later when the temperature warms will generally catch up with and surpass the growth of those planted earlier. Why bother? Early planting may buy you bragging rights but not much else.

Because tomatoes transplant well, you can start seeds indoors or purchase seedlings to be transplanted into the garden when the weather warms up. Plant seeds indoors six to eight weeks before you want to put the plants in the garden. Use a purchased seedling mix or make your own with equal parts of peat moss and perlite. Keep in a sunny room or greenhouse where the temperature is 65 to 70 degrees. Thin the seedlings and keep them moist until they are six to eight inches tall and ready to plant outside.

To ease the transition from house or greenhouse to garden, harden the plants first. A cold frame works well for this purpose, but you can also put the plants outside in the shade during the day and move them into the garage or basement at night for a week or two before planting.

To avoid disease, it's best not to plant tomatoes in the same location every year. Rotate tomatoes with other crops.

Prepare the soil by digging deeply and incorporating aged manure or commercial fertilizer. Tomato plants sprout roots all along their stems so set transplants deep in the soil, covering the stems up to the main foliage.

Plant seedlings 2 feet apart in rows 3 feet apart. All varieties need some form of support to keep the fruit off the ground. You can drive a six-foot stake into the ground and tie the plant to the stake as it grows. Or you can create a fence with stakes spaced 3 to 4 feet apart, looping heavy twine from stake to stake across plants. Alternatively, surround newly planted tomatoes with a wire cage. You can make a tomato cage from concrete reinforcing screen with a 6-inch mesh. Bend the mesh into a cylinder with a 1 1/2-foot diameter. Tomato roots grow at least 4 feet deep, so water established plants deeply once a week.

The number of tomato varieties available now to the home gardener can be overwhelming. Local trials and Master Gardener taste panels have created this partial list of varieties that do well in our growing conditions: Better Boy, Bragger, Celebrity, Champion, Early Girl, Quick Pick, Sweet 100, Supersteak, Whopper and Yellow Pear.

Local nurseries are also a good source of information. They tend to carry varieties that are suited to our area and have anecdotal data from a lot of customers. And one of your best sources of information is your successful tomato-growing neighbor.

Early Girl has been the workhorse in my garden for several years, repeatedly outperforming other varieties. I also enjoy experimenting with the wonderful colors and frequently intense flavors of many of the heirloom varieties, although they are not consistent performers in my garden. Last year my Yellow Pear, a pre-1800 variety, became the Plant that Ate Manhattan. It climbed to more than 8 feet and required extra caging and ultimately a 4-by-4 post to keep it upright because it was so loaded with fruit.

Here are some other interesting tomato facts:

* The botanical name for tomato is Lycopersicon esculentum.

* Refrigeration causes tomatoes to lose their flavor in only two days, so store at room temperature.

* Six to 10 plants will feed a family of four with lots left over to share with the neighbors.

* As of 1998, the heaviest tomato on record weighed 7 pounds, 12 ounces.

Good luck with your crop. And remember that patience pays. Your best chance of success with tomatoes is to wait and plant late into warm soil.

Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information.

Napa County Master Gardeners (www.mastergardeners.org) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to noon, at the UC Cooperative Extension office, 1710 Soscol Ave., Suite 4, Napa, 253-4221, or toll-free at 877-279-3065.

E-mail your garden questions by following the guidelines on the Web site. Click on Napa, then on Have Garden Questions?