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There's just nothing better than homegrown tomatoes––green, red, yellow or striped. Originating in Central and South America, the tomato was thought by early American colonists to be poisonous and was not recognized as a useful vegetable until the 1800s. It is true that tomatoes are a member of the Nightshade (Solanaceae) family. Although the Nightshade family evokes the thought of deadly poison, it includes 85 genera and approximately 2,800 species of plants, bushes, and trees. Plants of the Solanaceae family that are found in vegetable gardens vary from potatoes and chili peppers to petunias and eggplants. Only a few varieties of Nightshade are poisonous.

Tomatoes are warm-season perennials grown as annuals. They vary in size from the tiny and sweet cherry style tomatoes to big juicy and meaty beefsteak tomatoes weighing more than a pound. When grown as staked plants, tomatoes require a relatively small amount of space, yet are capable of producing 8 to 10 pounds or more of fruit per plant. Tomatoes are low in calories and a good source of vitamin C.

They are warm-season plants and should be planted only after danger of frost has passed. Temperature is an important factor as they are particularly sensitive to low night temperatures. Blossom drop can occur in early spring when daytime temperatures are warm, but night temperatures fall below 55 degrees F as well as in summer, when days are above 90 degrees F and nights above 76 degrees F.

There are probably more tomato cultivars available to the home gardener than any other garden vegetable. Tomatoes are usually categorized as early, mid-season or late. Another consideration is whether the tomato cultivar you choose is determinate or indeterminate in growth habit. Determinate (D) tomato plants (also called bush) grow to a certain height and then stop.

They also flower and set all their fruit within a relatively short period of time. This is an advantage if the tomatoes are being grown primarily for canning purposes. Indeterminate tomato plants grow, flower, and set fruit over the entire growing season.

Another characteristic to look for when choosing tomato cultivars is disease resistance. Many cultivar names are followed by one or more letters. The letter 'V' indicates that the tomato variety is resistant to 'Verticillium wilts'; 'F' stands for Fusarium wilt resistance and 'N' for nematode resistance. Both Verticillium and Fusarium cause wilting of the leaves and nematodes are microscopic worms that attack, and eventually destroy a tomato plant's root system. Disease resistance can be an important consideration, especially if you have experienced these problems with tomatoes in the past.

You can start plants indoors 4-8 weeks before the last frost. Unless you have a large space and plenty of lighting, trying to start them any earlier will gain nothing. Plants that have compacted, circular root balls will just sit in the soil for a couple of weeks while they establish new roots and lose any flowers or fruits they might have had. On the other hand, plants that have not outgrown their containers will almost instantly begin to grow when they are transplanted into warm garden soil.

Tomato seeds will germinate best at 75-80 degrees. Although they will germinate at lower temperatures, it will take much longer and your germination percent will be lower. Once the plants have their first true leaves you should grow them at about 65 degrees. A night time drop of about 10 degrees would be ideal.

Wait to transplant them to larger containers until they have their first true leaves. If you use cell packs, they should be transplanted again once the plants start touching each other. The seedlings need a minimum of eight hours of light per day. Expensive grow lights are not necessary. Fluorescent shop lights work very well. Keep the lights 3-4" above the top of the plants.

Before placing young plants in the garden they should be hardened off. Plants taken directly from the house or greenhouse to the garden almost always scorch from exposure to direct sunlight and wind. Scorched plants turn white or brown. Plants not killed will certainly be set back.

Harden off the seedlings by placing them outdoors for several hours on mild days. Select a shady, sheltered area at first. After several days you should provide some sun in gradually increasing amounts. Plants may be left outside if temperatures are mild. Begin this process at least two weeks before the plants are to be set out in the garden.

The emphasis of our 'Growing Edibles' class series will switch from fruits to vegetables April 11. The class that evening will be on growing tomatoes, peppers and eggplants. Besides basic growing requirements, we will talk about different varieties and disease control. Seeds of several heirloom varieties will be available for sale.

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The next class in the spring series offered by the Chisago County Master Gardeners is GROWING BLUEBERRIES taught by Master Gardener, Diane Patras. It will be Tuesday, April 4, at the Senior Center in North Branch at 6:30 p.m.

The brochure for the entire 'Growing Edibles' series is on our web page in the 'Hot Topics' box: http://www.extension.umn.edu/county/chisago. You can also call 651-674-4417 to have a brochure mailed to you. Although walk-ins are welcome, we ask that you pre-register so that enough handout materials will be available.

The Master Gardener voicemail is available all year long at 651-674-4417. During office hours ask for the Master Gardener voicemail, after hours, select ext. 18.

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