Tomatoes are a must for all summer vegetable gardens. Whether you grow the large beefsteak variety or the prolific cherry tomato, all tomatoes benefit from regular, periodic applications of plant food. The type of fertilizer depends on when during this plant's life cycle you apply it. When plants are young, they need a balanced plant food, but they benefit from a food that is lower in nitrogen when they begin to flower and set fruit.
The tomato comes to us from its native Central and South America, where it's been a staple food of indigenous peoples since humans arrived in its native regions. Early American colonists were afraid to eat tomatoes, fearing the plants were poisonous, so tomatoes didn't become standard foodstuff in North America until the 1800s. Many varieties of tomatoes exist, both hybrids and heirlooms.
Tomato plants are hardy, fast-growing summer vegetables. They benefit from staking or caging to keep their fruit supported above the damp earth, where insects and creatures such as snails and slugs will eat them. They prefer rich, well-draining, slightly acidic, loamy soil enriched with compost. Tomatoes do well when you plant them in a sunken basin, which you can flood with water to give them a thorough soaking when the soil becomes dry. Tomatoes will set fruit only when springtime temperatures are above 55 degrees F at night.
After the danger of frost has passed in the spring, set out young tomato plants in the garden. Dig 2 cups of organic compost into each planting hole and then remove a couple of shovelfuls of soil out and build a berm, or ridge, of soil around the central area, which will be recessed. This provides a good growing space for tomatoes---because when you water them, it's best to flood them so they can soak up the water thoroughly. Tomatoes need no fertilizer when you first plant them, especially if you amend their soil with compost.
Early Season Fertilizer
Tomatoes thrive when you give them a balanced fertilizer about two weeks after planting. A plant food such as Miracle Gro MaxFeed Tomato is a soluble plant food designed for tomatoes. This type of food has an N-P-K ratio of 15-2.2-9.0. If you prefer organic fertilizer for your tomatoes, spread a 2- to 3-inch layer of compost in their planting basin; every time you water, nutrients will leach into the soil. Tomatoes also respond well to monthly applications of fish emulsion. Tomatoes do well with organic fertilizers and do not necessarily need the strong boost of nutrients that chemical fertilizers provide.
Later Season Fertilizer
After your tomato plants start to bloom, and when they first start to set small fruit, it helps to apply a low-nitrogen, or "blossom booster" fertilizer to encourage flowering and fruit setting. A fertilizer having an N-P-K ratio of 10-30-10, 15-30-15 or 10-20-20 is recommended. Granular fertilizers that you mix with water are available commercially, such as Miracle Gro Bloom Booster or General Organics BioBud Bloom Booster. Be sure not to feed your tomatoes with a high-nitrogen fertilizer after they begin to set fruit, because the plants will develop excess foliage and an insufficient number of flowers and fruit.