Sure, lettuce is easy. Radishes are fast. But if you’re only going to grow one vegetable, chances are it will be tomatoes.

Americans love tomatoes. We ate more than 20 pounds of fresh tomatoes per capita in 2007, according to the Agricultural Marketing Resource Center, and the USDA estimates we consumed almost three times that much processed into pizza, pasta sauce, ketchup, salsa and other things that come in cans and bottles.

What makes a tomato worth growing at home, though, is that it’s nothing like a canned one. And if you grow tomatoes at home, you can plunge into a rainbow world of tastes, shapes, colors and pedigrees.

Yet though the tomato is the first vegetable most gardeners want to try, it isn’t the easiest one in the world to grow. Tomatoes can be tricky.

Let’s start with basic knowledge:

• Tomatoes are tropical. Domesticated tomatoes originated far south of here, in Central America, where the days are long, sunlight is ample throughout the year and the soil always is warm. Growing in regions where the season is shorter doesn’t come naturally to them. They need considerable help.

• Tomatoes are vines. In their natural form, they can sprawl wildly for 10 feet or more on the ground. Some cultivated varieties have been bred for a more bushy form that’s easier to control; there even are dwarf kinds for growing in pots. But you need to choose carefully and be prepared to cope with your variety’s size and straggle.

• Sun and soil. The most important part of tomato growing is selecting and preparing the site before you plant. Your spot, whether garden bed or large container, must get at least eight hours of sun a day all season. It’s essential to have rich, well-drained soil that includes plenty of organic matter such as compost or shredded leaves. That will let air and water flow freely and support beneficial microorganisms.

• Water. Consistent soil moisture — not too wet, not too dry, not swinging back and forth, even when the plants get big and thirsty — is key to success with tomatoes. “How are you going to get water to the plants?” says Stephanie Turner, director of seed product at Park Seed Co. (parkseed.com). “That needs to be planned out strategically beforehand.”

• Space and size. It’s easy to underestimate how large an 8-inch-tall seedling will grow to be — and how heavy it will get when it is laden with ripening fruit. Allow at least 3 feet between plants; crowded plants without enough air circulation don’t dry off and are more vulnerable to disease, says Duane Mieland, tomato grower for Sid’s Greenhouses in Palos Hills, Ill., and Bolingbrook, Ill., (sidsgreenhouse.com). A container must be at least 2 feet in diameter to allow enough space for a tomato plant’s roots and the soil and water for it. Plan for sturdy support in the form of stakes, a trellis, a porch railing or a cage of stout wire fencing.

• It’s easy to get in too deep. Tomatoes need regular attention — watering, pruning off unwanted sprouts and stems, inspecting the plants for insects and disease, tying the vines to their supports, harvesting, and dealing with wrinkles such as cucumber beetles and cutworms. Two or three plants should be enough to give you a satisfying tomato experience while you learn and gain confidence to expand your tomato farm next year.

• Seek help. There’s a boom in vegetable gardening expected this year, according to Susie McCoy, trendmeister with the Garden Media Group in Chadds Ford., Pa. Garden centers and catalog companies want to help newbies succeed so they will become longtime customers, so don’t hesitate to ask for help in choosing plants, containers or soil amendments.