Use Biodegradable Pots
Peat pots make planting extra easy: Just dig the hole, put in the plant, and fill in with soil. There's no need to take your plants out of the pot.
Here's a hint: Cut off any extra peat-pot sides that stick up above the potting mix. If you don't, the peat pots will dry out faster than the surrounding soil, leaving your tomato plants thirsty and suffering.
Feed Them Well
Like growing kids, tomatoes are heavy feeders, so add plenty of organic matter (such as compost) to the soil. Give them an early boost by working a little fertilizer into the soil at planting time.
Tomato plants form roots all the way along their stems, so you can give your plants an extra-strong root system (especially the tall, leggy ones) by planting them on their sides. Do remove any leaves that would be covered under the soil, though. Buried leaves could rot and encourage disease.
It's always a good idea to give freshly added plants a little extra water the first week or two after you plant them to help them get established. They're most susceptible to drying out when they're young.
There are two basic categories of tomatoes: determinate and indeterminate. Determinate tomatoes, sometimes called bush tomatoes, put on most of their growth before they start to bloom and produce fruit. Indeterminate tomatoes keep growing after they start to bloom -- so the plants can become quite large (more than 6 feet tall). Stake indeterminate tomatoes to keep them standing. It will help keep the plants healthy and make the fruits easier to harvest.
Plant in Pots
Try planting your tomatoes in containers if you've had trouble growing them in the past. Large containers filled with a high-quality potting mix give your plants more protection from fungal diseases.
Here's a hint: Choose a big container for your plants. The bigger the pot, the less often you'll have to water.
Try Red Mulch
We know mulch is good for the garden -- but university research suggests that red plastic mulch may make your tomato plants more productive. (One study showed yields increased by 20 percent by using red mulch.) Red mulch also helps the soil conserve moisture longer during hot, dry periods and inhibits weeds.
Keep Out Cutworms
Hungry cutworms attack young vegetables. Protect your tomatoes by giving them a collar of newspaper. Or cut the top and bottom off a tin can and sink that into the soil around your plants. It creates a barrier that forces the cutworms to go looking for another dinner.
Protect Them from Cold
You can use a variety of devices to protect your tomatoes from the cold if you want to get a jump-start on the tomato-growing season. One of the easiest is a simple cloche made from an old milk jug; simply cut the bottom of the jug and set it over your tomato plants. Leave the top open so the cloche doesn't get too hot inside during sunny days.
Keep the Foliage Dry
Tomatoes are susceptible to a number of diseases. To keep your plants healthy, water with a soaker hose. This helps the foliage stay drier; wet foliage (especially in late afternoon, evening, and nighttime hours) can encourage common fungal diseases such as blight.