Tomatoes

How to Grow Tomatoes

There are three types of plant growth for tomatoes:

  • Determinate - Determinate tomato plants are relatively compact and produce a full bushy plant. These plants will reach a predetermined height or number of fruit clusters and not grow beyond it. The plants flower, set fruit and ripen in a short time so that the main harvest is concentrated into a few weeks. This may be ideal for gardeners who wish to can or preserve the fresh tomato harvest. Instead of three leaf stems and a flower cluster, determinate varieties have two leaf stems and a cluster.
  • Indeterminate - Plants grow, blossom, and produce tomatoes throughout the growing season.  The continuous growth produces many main stems, all capable of flowering and producing fruit.  To identify and indeterminate plant, look at the main stem, which can be identified by the growing tip at the top or end of the stem.  In a normal plant, there are three leaf stems growing from the main stem. Above or below the three stems you will find a flower cluster. This pattern is repeated over and over on the main stem.  To support the plant growth and to keep tomatoes off the garden soil, it is best to stake the tomato plant.When staking tomatoes, put the stake in shortly after transplanting to lessen root damage. A 6-foot stake set 10 inches deep in the soil will work well. As the plant grows taller, tie it loosely to the stake every 12 inches with pieces of rag or twine. Plants can be easily trained to the stake for vertical growth.  The excess of abundant, lush growth, means pruning indeterminate plants is highly recommended. Indeterminate plants should be pruned to harvest larger tomatoes. Without pruning, plants produce smaller tomatoes but more of them. To prune, pinch out suckers. These are shoots that develop in the "U" between the main stem and a branch. Pinch out these shoots. This is best done by hand, pinching the shoots between fingers.  Caging is another way to train tomato plants. Put cages over the young plants. Push the cages down into the soil to keep them from blowing over. This way, the vine has support without being tied. Tomatoes growing in cages do not need to be pruned.
  • Semi-determinate - A bushy plant that will set and ripen fruit over a longer period of time than a normal determinate.  The best way to grow determinate or semideterminate plants is to NOT prune and place a cage around the tomato while still quite small. The plant grows filling the cage. Gardeners need only pluck ripe fruit.  

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How to Start Tomatoes from Seed

Many gardeners start their tomato plants from seed. This allows gardeners a wider choice of tomato varieties than if purchased as bedding plants. Tomato seed should be sown indoors 6 to 12 weeks before the last expected frost date. Most seed will germinate in 5 to 12 days. For maximum germination, the soil temperature needs to be warm, about 70 to 75 degrees F. Use a prepared, sterile germination mix as the growing media. Place this media in containers with holes for drainage. Water the media thoroughly and allow to drain. Sow seeds on the media and cover lightly with media or vermiculite. Mist the top of the media and cover with newspaper or plastic to prevent the media from drying out. Keep in a warm place and check every day for germination. When seeds have sprouted, remove the cover. Place in a sunny location, keep seedlings warm and water regularly. After a week or two transplant young plants into small 2 inch individual peat pots filled with a sterile soilless growing media. Dig out plants, carefully separate and disturb the roots as little as possible. Make hole in media, place plant into hole and push media next to plant to hold it upright. The plant can be planted deep, to the first leaf stem. Roots will develop along the buried main stem. Provide as much direct sunlight as possible. Up to twelve hours of light is desirable at this stage. Gardeners can use grow lights to supplement the natural sunlight. The plants may stretch or get leggy if they do not receive enough direct sunlight.

How to Transplant Tomatoes

Garden soil needs to be prepared to grow transplants. Digging soil to add air pockets to the structure is advised for heavy clay soil. It is good to begin with a soil analysis to learn if any important nutrients are missing. Your local cooperative extension agency can assist you with information about a soil test. There are soil test kits available in stores too. Add compost and other organic materials to your soil to improve nutrients, texture and moisture holding capacity. Break large clods of soil into small pieces. Rake the garden bed so that it is flat and level.It is recommended to harden off plants before placing them in the garden. The young plants are tender and need to be exposed gradually to the harsh outdoor climate. Put plants outside in a protected area where they will receive full sun, but out of the wind. Move plants inside at night. Continue this for 3 to 4 days. The day and night temperatures should be increasing but if it drops to 50 degrees, take the plants inside. After four days allow plants to be outside all day and night. After being outside for a week or two, the plants should be hardened off and ready to transplant.

How to Plant Tomatoes

Tomatoes are one of the easiest garden plants to grow. They need as much direct sunlight as possible to produce the highest yield. Wait until the air and soil have warmed before transplanting tomatoes. Native to the tropics, tomatoes require warm, 70 degrees F, temperatures for good growth.  There are several ways to plant a tomato. The traditional method is to dig a hole in the soil and place the plant in it. For northern gardeners, if your plants are tall and leggy, don't worry, just dig a deeper hole and bury the plant to the first leaf stem. The buried stem will grow roots and this helps develop a deep root system. This deep hole planting is not recommended for southern gardeners due to fungal rot attacking young stems. Some people use the trench method of planting. A long shallow hole is dug and the tomato plant laid horizontally into the trench. Pinch leaves off of the stem. Allow the top two to three inches of stem to lead out of the trench. Push soil on top of trench and push a pillow of soil under the top stem. The stem will grow up towards the sun. Because the bulk of the stem is buried at a shallow level, the newly developing roots and surrounding soil will warm up relatively quickly. This is a boon to gardeners living in a short growing season. With the roots close to the surface, be sure to water deeply to encourage deep root growth.

After planting, water. Continue watering lightly each day if it does not rain. After about 2 weeks of regular watering, plants should be established and you can decrease the watering. Throughout the growing season make mental notes about how long it has been since it rained. If it does not rain one week, be sure to water tomato plants as long as they are setting fruit. Established tomato plants need about one inch of precipitation per week from rain or irrigation.

Gardeners living in short growing seasons have garden supplies that can help protect plants from cold temperatures. A cloche or hot cap can be used to protect the newly transplanted tomatoes from freezing if night temperatures drop. Tomato plants will probably die if exposed to 32 degrees F without protection as they are not frost tolerant.

How to Fertilize Tomatoes

Tomatoes need phosphorus, nitrogen, potash and minor elements. Many gardeners add a fertilizer to the soil. There are many types of fertilizer. Some are water soluble and can be used when watering tomatoes. There are granular forms to add to the soil before planting. The easiest to use is a time release fertilizer at the time of planting. No matter what kind of fertilizer is used always follow the directions on the label. Do not over fertilize because then you will have lush, tropical plants with little fruit set. Be sure to select a fertilizer that contains more phosphorus (P) than nitrogen(N) or potassium (K). Phosphorus promotes flowering and fruit set.

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How to Grow Tomatoes in Containers

Gardeners living in urban environments can grow tomatoes in tubs or large patio containers. For best results select a determinate or compact bush plant habit for container culture. Cherry tomatoes can be grown in containers too. The container needs to be deep, at least a foot, with drainage holes on the bottom. Use a sterile growing media. Keep the plants evenly watered without over watering. Allow the plants to receive as much direct sunlight as possible. Low light levels result in a leggy plant.  They will still produce fruit, just fewer of them. Feed plants using a water soluble fertilizer. Apply as directed on the label but remember, nutrients tend to leach out of the pots faster than garden soil. Water often during hot weather possibly 3 or 4 times weekly as needed.

How to Harvest Tomatoes

To achieve the full tomato flavor, allow the fruit to fully ripen on the plant. Wait until it is deep red, or whatever final color the tomato is to be. Remember that once harvested, no additional sugars will go into the fruit. To harvest, gently hold the tomato and twist the tomato so that the stem separates from the vine. It is easy to damage the plant by pulling the entire fruit cluster off of the plant. Take the fruit one at a time unless you wish to remove the entire ripe cluster. Tomatoes are best stored at room temperature. It is absolutely unnecessary to place a ripe tomato in the refrigerator. Tomatoes will store on a kitchen counter for several days. At the end of the season when frost is predicted, all green tomatoes can be harvested and placed on a windowsill for future use. Most will gradually turn red and have some degree of tomato flavor. Placing unripe tomatoes in a closed paper bag will hasten the ripening process.

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We acknowledge two tomato experts who read the information sheet and contributed their knowledge: Julia Pruitt, Oklahoma State University, Oklahoma City, OK and Jim Waltrip, Seminis Vegetable Seeds, Saticoy, CA.

A special thanks to the National Gardening Bureau for this article.