Summer-ripened tomatoes are a good source of vitamin C and beta-carotene. The lycopene in the tomatoes is an anti-oxidant, but is only released when the tomatoes are cooked. They also contain compounds that block cancer-causing nitrosamines.
Tomatoes like fertile, well drained soil that is rich in organic matter. Dig in finished compost and manure, and add 1 cup balanced organic fertilizer beneath each transplant. The nutrition from heavy clay soils is excellent for tomatoes, but they are slow to warm, so transplanting should be done later. By the same token, lighter soils warm more quickly, so transplants can go out sooner. Adding glacial rock dust will supply all the calcium they will need. Regular watering is vital, but don’t let the plants sit in water. Tomatoes are tropical plants so they require full sun and lots of heat.
Stop watering around the end of July to encourage the fruit to ripen. If tomato plants are grown under cover, you can encourage pollination and fruit set by tapping the stem from time to time. Tomatoes do not rely on insects for pollination. Vibrating the plant shakes pollen loose within the flowers, which then self-pollinate.
Harvest when the fruit is the desired colour. Green tomatoes can be ripened indoors at a cool temperature when they are blemish free. Very dark green tomatoes are unlikely to ripen fully.