Tomatoes are the most popular vegetable in the home garden. Tomatoes are available in a wide variety of colors, sizes, and shapes. While most tomatoes are red, there are also yellow, orange, pink, purple-black, and green varieties (cultivars). Sizes vary from the bite-size grape tomatoes to the giant beefsteak cultivars. Tomatoes may be round, oval, oblate (fruit are flattened at the top and bottom), elongated, or pear-shaped.
Tomatoes also vary in growth habit. Tomato cultivars are classified as determinate or indeterminate. Determinate tomatoes are small, compact plants. They grow to a certain height, then flower and set all their fruit within a short period of time. The harvest period for determinate tomatoes is generally short, making them good choices for canning. Indeterminate tomatoes continue to grow, flower, and set fruit until killed by the first frost in fall. Accordingly, the harvest from indeterminate cultivars often extends over a 2 or 3 month period. Yields are generally heavier than determinate types, but are usually later to mature. Indeterminate tomatoes are large, sprawling plants which often perform best when grown in wire cages or trained on stakes.
Transplant tomatoes into the garden after the danger of frost is past. In central Iowa, it's usually safe to plant tomatoes around May 10. Gardeners in southern Iowa can plant one week earlier, while those in northern areas should wait an extra week. The last practical date for planting tomatoes is approximately June 20.
When purchasing tomato plants at your local garden center, select stocky, dark green plants. Avoid plants with fruits. The fruits will stunt plant growth and reduce total yield. Harden or acclimate the plants to outdoor conditions before transplanting into the garden. Initially place the plants in a shady location, then gradually expose them to longer periods of sunlight. After several days of hardening, the tomato plants should be ready to be planted into the garden.
Tomatoes require full sun. Select a planting site that receives at least 6 hours of direct sun each day. If the plants are in peat pots, tear off the top edge or make sure the top edge is well below the soil surface once planted. If the top edge of the peat pot is exposed to the air, it will act like a wick and draw water from the soil around the plant. Carefully remove plants from plastic cell packs by gently squeezing the bottom on each compartment. Plants in plastic pots can be removed by tipping them on their sides and tapping the bottom of the pots.
Set plants into the soil up to their first true leaves. Pinch off the bottom leaves of tall, lanky transplants and lay them sideways in a trench. Carefully bend the stem upward so that the upper few inches of stem are above the soil surface. Roots will develop all along the buried stem.
Spacing of the plants depends on the growth habit of the cultivar and training system employed. Indeterminate cultivars that are staked can be planted 2 feet apart in the row. Indeterminate plants grown in wire cages should be spaced 2½ to 3 feet apart, while a 3- to 4-foot-spacing would be appropriate for indeterminate tomatoes allowed to sprawl over the ground. Determinate tomatoes can be planted 2 to 2½ feet apart. Rows should be spaced about 4 feet apart.
After transplanting, water the tomato plants with a dilute fertilizer solution. Use a water soluble fertilizer following label directions or dissolve 1 or 2 tablespoons of a complete garden fertilizer, such as 10-10-10, in one gallon of water.
Suggested tomato cultivars for Iowa include 'Better Boy' (indeterminate; red, round, medium-sized fruit), 'Big Beef' (indeterminate; red, oblate, large fruit), 'Brandywine' (heirloom; indeterminate; deep pink, oblate, large fruit), 'Carolina Gold' (determinate; golden orange, oblate, large fruit), 'Celebrity' (determinate; red, oblate, medium to large fruit), 'Cherokee Purple' (heirloom; indeterminate; purplish brown, oblate, large fruit), 'Jet Star' (indeterminate; red, oblate, medium to large fruit), 'Mountain Fresh Plus' (determinate; red, globe-shaped, large fruit), 'Pony Express' (determinate; red, elongated, medium-sized fruit), 'Solid Gold' (indeterminate; golden yellow, oval, small, grape-type fruit), and 'Supersweet 100' (indeterminate; red, round, small, cherry-type fruit).