Where you plant your tomatoes and the type of soil you use is very important, according to the National Gardening Association. Gardeners all around the world often treat tomatoes badly. Tomatoes are hardy enough that even in difficult conditions, they will usually produce something, but a good location and soil may mean the difference between some tomatoes and a bumper crop.
The three basic types of soil are sand, silt, and clay. It is possible to grow tomatoes in any of the three, but some are better than others. The very best soil is a combination of the three, commonly referred to as loam. A loamy soil is thick, rich, dark, and has the ability to hold nutrients, yet is not so thick that it will not drain. Of the three, sand is the worst type of soil for tomatoes. Sand is a very loose soil that drains quickly. This may sound like a good thing because it won't allow water to pool under the plant or around the roots and cause rot, but sand also doesn't keep water near the plant long enough to allow the roots to soak up water and food. Sandy soil drains so fast that most nutrients leech away completely, leaving nothing behind to nourish the plants. Clay soil is so thick that pools of water accumulate around the plant and cause rot and mildew. Silt is a combination of clay and sand and is closer to ideal, although a perfect condition includes all three soil types in equal measure to make a light, airy, but firm foundation for your tomato plants.
The level of pH in the soil is important for tomato growth. Tomatoes prefer a soil that leans just a little toward acidity. Buy a test kit at your local garden or department store. If your soil is too acidic (has a pH of less than 6), add some garden-grade lime or sulfur to the ground in the spring and mix in thoroughly. Neutral on the pH scale is 7, so try to keep the pH level around 6 and the plants will thrive.
Till a generous amount of fertilizer into the soil in the spring before planting. Look for a commercial blend of 5-10-10 (5 nitrogen, 10 phosphorous, and 10 potassium). Tomatoes crave higher levels of phosphorous and potassium. This creates a good foundation for your plants. In addition to a good commercial fertilizer, create a compost of leaves and other organic matter the season before and work it into the soil in the spring to build up weak soil and loosen extremely thick soil. The additional nutrients in compost create extra benefits for tomatoes. Compost adds extra calcium that tomatoes crave.