The life cycle of a tomato plant is relatively short. Tomato plants are annuals and, as such, only last for one growing season before they die. Typically, tomatoes don't live an entire 12-month year, but the length of their life will vary a bit depending on the climate they are in as well as on the variety of tomato being grown.
Because tomatoes thrive in warm weather, seeds should be planted after all danger of frost is past. Plant too early and the resulting plants are likely to drop their flowers without producing fruit. Each tiny seed has everything it needs to produce a healthy, productive plant as long as it is given the right conditions to germinate.
Tomato seeds should be planted in well-drained, loamy soil with a pH around 6.2 to 6.8. You can give your seeds a head start by planting them indoors about six to eight weeks before the last predicted frost date for your area. If soil is kept moist and soil temperatures stay around 75 to 90 degrees F., the seeds will germinate successfully.
After a week or two, you will see a little sprout poke up out of the soil. It will have two small leaves called cotyledons. These leaves will disappear after the seedling gets a bit bigger and true leaves form. Make sure they have plenty of bright light so they grow strong and straight instead of leggy and scraggly.
If you have multiple seeds planted in the same area, you will need to thin them after the second or third set of true leaves has formed. This is usually done 3 to 4 weeks after the seed has been planted. Keep only the biggest, healthiest-looking seedlings and pull the rest. If you have started your seeds indoors, you will need to transplant them, one per 4-inch pot. Seeds started outdoors should be thinned so the plants are two to three feet apart. This allows room for growth without overcrowding.
Around five weeks after planting seeds, the tomato plant should be large enough to plant outdoors or in a large pot. If you choose a pot, make sure it is very deep to allow for strong root development. The pot should also offer proper drainage.
Transplants can be planted deep, with the soil coming up to the bottom leaves. The part of the stem that is under the soil will develop roots which help the plant absorb nutrients. Another method of planting is to make a trench and lay the plant lengthwise in it. Cover with soil up to the leaves, allowing the leaves to stay exposed. The plant will grow upwards and the roots will be strong and healthy.
Flowers will soon start to form on the tomato plant. Tomato flowers are self-fertile. This means even if you only have one tomato plant, you can have tomatoes. Pollination is done by bees or through the shaking of the plant when the wind blows.
Flowers are small and yellow, and typically form in clusters. The time it takes for flowers to form depends on the variety of tomato you have planted as well as on the temperatures they are growing in. If you get a sudden frost, you will lose the flowers and will have to wait for more to form.
Fruits will form not long after the flowers appear. These will also vary in the time required for ripening. Early varieties of tomatoes can produce fruit within 60 to 69 days after the seed is planted. Small container varieties may be ready after only 45 days. Main crop varieties are ready to harvest 70 to 79 days after planting. Late maturing types are ready 77 to 85 days after they have been planted.
As the days grow shorter and summer draws to an end, the tomato plant will begin to wither and die. Be sure to harvest any remaining green tomatoes before the first frost. And don't forget to save seeds from the tastiest varieties if you have grown heirloom varieties of tomato. If you do, you can start the tomato life cycle all over again next spring.