Tomatoes (Solanum lycopersicum) are the most popular vegetable crop in the home garden. There is nothing quite like a tomato fresh from your garden!
They are available in a variety of sizes, shapes, and colors. Fruit size varies from bite-sized cherry tomatoes to giant beefsteak cultivars. Tomatoes may be round, oblate (fruit are flattened at the top and bottom), or pear-shaped. Tomato fruit may be red, pink, orange, yellow, green, or purple. (Figure 1) Tomatoes are low in calories and a good source of vitamin C and antioxidants.
Types & Recommended Cultivars | Planting | Care | Training | Pruning | Harvest & Storage | Potential Problems | Growing in Containers | Seed Saving | More Information
Types & Recommended Cultivars
Tomatoes can be classified based on several different characteristics including growth habits, fruit shape, and color, among other things.
Learn more about the different types of tomatoes, from determinate vs. indeterminate to hybrid vs. heirloom, as well as the many recommended cultivars for the Iowa garden in this article: Recommended Cultivars and Types of Tomatoes for the Home Garden.
Planting
Ideal Growing Conditions
Tomatoes can be successfully grown in many different soil types but perform best in deep, loamy, well-drained soils. Tomatoes prefer a slightly acidic soil with a pH of 6.0-6.8 but can be grown in slightly alkaline soils. Tomatoes need at least six hours of direct sun daily for best yields.
Starting Seed Indoors
Tomato plants can be started indoors or purchased at garden centers. Tomato seeds should be sown indoors 5-6 weeks before the intended outdoor planting date. After germination, place the seedlings under artificial lighting or in a sunny window.
Learn more about growing tomatoes from seed in this article: How to Successfully Start Seed Indoors.
Buying Transplants
When purchasing tomato plants, select stocky, dark green plants that do not have fruits. Fruit development on young plants stunts growth and reduces total yield. Look for plants that show no signs of disease or insect damage.
Learn more about selecting quality plants in this article: Tips for Shopping and Selecting Quality Plants.
Hardening
Whether grown indoors or purchased from a garden center, transplants should be properly hardened before placing them in the garden. Initially, place the plants in a shady location out of the wind, then gradually expose the plants to longer periods of sunlight. After several days, the tomatoes should be ready to be planted in the garden.
Learn more about hardening tomatoes in this article: Selecting, Hardening, and Planting Bedding Plants.
Transplanting
Transplant tomatoes into the garden after the danger of frost has passed. This is typically early to mid-May in Iowa. To obtain good yields, the last practical date for planting tomatoes is June 20.
If plants have been started in peat or coir pots, tear off the top edge or ensure the top edge is well below the soil surface once planted. If the top edge of the pot is exposed to the air, it will act like a wick and draw water away from the plant. If the tomatoes are in plastic pots or cell-packs, carefully tap out the plants. Use a sharp knife to cut around plants growing in small flats.
Set plants into the soil deeply, up to their first true leaves (Figure 2). Pinch off the bottom leaves of tall, spindly transplants and lay the stem sideways in a trench. Carefully bend the stem upward so that the upper few inches of the stem are above the soil surface. Roots will develop all along the buried stem. (tomatoes are the only vegetables that can be planted successfully in this manner.)
Spacing
Plant spacing depends on the growth habit of the cultivar and the training system. Indeterminate cultivars that are staked can be planted 1.5-2 feet
apart within rows. If grown in wire cages, space plants 2-3 feet apart. Tomatoes allowed to sprawl over the ground should be spaced 3-4 feet apart. Rows should be spaced 4-5 feet apart.
Determinate tomatoes can be planted 1.5-2 feet apart in rows 4 feet apart.
Care
Water
Like most vegetables, tomatoes perform best when they receive one inch of water per week. Supplemental watering is best done in the morning and applied directly to the soil surrounding the plants. Avoid overhead irrigation as it splashes soil, helping to spread common diseases like septoria leaf spot.
Soil type does not affect the total amount of water needed but does dictate watering frequency. Sandy soils require more frequent water applications, but less water applied per application.
Consistent watering is essential, especially during fruit development. Plants that do not grow with even soil moisture can develop cracks and blossom end rot.
Fertilizing
If a soil test has not been conducted, apply and incorporate 1-2 pounds of all-purpose garden fertilizer, such as 10-10-10, per 100 square feet before planting. Three to four weeks after transplanting, fertilize the tomato plants with a dilute fertilizer solution.
Use a water-soluble fertilizer or dissolve 1-2 tablespoons of 10-10-10 or a similar analysis fertilizer in a gallon of water. Depending on soil fertility, an additional fertilizer application may or may not be required. Over-fertilization promotes excessive vegetative (leafy) growth and may inhibit fruit development.
Mulch
Apply a mulch to the soil surface around tomato plants to:
- conserve moisture and help maintain a consistent soil moisture level
- control weeds
- moderate soil temperatures
- reduce disease problems
- reduce fruit spoilage
- keep fruit and leaves free of rain-spattered soil
Several organic materials can be used as mulches. These include lawn clippings, shredded leaves, straw, and pine needles (Figure 3). Do not collect grass clippings from lawns that have been treated with a broadleaf herbicide until it has been mowed two or three times. A 2- to 3-inch-thick layer is usually adequate, depending on the material.
Black and other colors of plastic mulch are often used by commercial growers to achieve an earlier crop, higher yields, control weeds, conserve moisture, and improve fruit quality. Plastic mulches are not cost-effective for home gardeners.
Weeding
Controlling weeds is beneficial for all vegetable crops, including tomatoes. Remove weeds through light cultivation. A layer of mulch can be used to suppress new weed growth. Learn more about weed control in this article: Weed Control in the Vegetable Garden.
Training
Training tomatoes provides several advantages in the home garden. Training tomatoes conserves valuable garden space for gardeners with small plots. Trained tomatoes are easier to cultivate and harvest. Foliar disease problems are generally less severe because of better air circulation. Plus, trained tomato plants often produce better quality fruit than those allowed to sprawl on the ground.
Training methods vary, but the three most common methods are the single stake, wire cage, and weave system (Figure 4). Learn more about these systems in this article: How to Train Tomatoes in the Home Garden.
Pruning
Pruning is the removal of suckers. Suckers are small stems that grow between the main stem and the leaf axil (Figure 5). By pruning out suckers, the gardener can increase yields and open up the canopy to allow for better air circulation, helping to reduce the potential for foliar diseases.
Learn more in this article: Pruning Tomatoes in the Home Garden.
Harvest & Storage
Harvest
The fruit of most tomato cultivars generally begins to ripen in August. Fruit production for early maturing cultivars such as ‘Early Girl’ or many cherry and grape tomatoes generally begins mid-to-late July.
Tomatoes should be allowed to ripen fully on the plant. Pick carefully from the plant when the entire fruit is a uniform color (Figure 6). When ripe, the fruit will be slightly soft to the touch, rather than firm or hard like unripe green tomatoes. The fruit of most cultivars is red when fully ripe. However, in hot weather, the fruit of red-fruited cultivars is often yellow-orange. The red pigments in tomato fruit don’t form well when temperatures are above 90°F.
Storage
Fully ripe tomatoes may be stored in the refrigerator, but only for a few days as the texture and flavor deteriorates over time. Tomatoes can be stored at room temperature for 5-6 days. Tomatoes can also be dried, frozen, canned, juiced, or puréed for later use.
Ripening of Green Tomatoes
When frost is imminent, mature green tomatoes can be harvested and ripened indoors. Just before the first frost, remove all mature, greenish-white fruit from the vines. They should be solid, firm, and free of defects (Figure 7). Remove the stems, then clean and dry the fruit.
Individually wrap each tomato in a piece of newspaper. Store wrapped tomatoes in a cool (60 to 65°F), dark location, such as a basement or cellar. The wrapped fruit can be placed in a single layer in a box or on a table.
Inspect the tomatoes frequently and discard any damaged or decaying fruit. When the tomatoes begin to color, remove the newspaper and place them at room temperature.
An alternate method is to leave the green fruit on the vine and pull up the entire plant. Hang the tomato plant upside down in a cool, dark location. Pick the fruit as they ripen.
Potential Problems
Many diseases, disorders, and insect pests can affect tomatoes during the growing season (Figure 8). For many home gardeners, diseases and disorders are the most common problems.
To manage diseases, a combination of cultural tactics is needed. This includes:
- Select varieties with disease resistance.
- Water and fertilize to maintain plants in a vigorous condition.
- Avoid fluctuations of too much and too little water.
- Keep foliage dry.
- Eradicate weeds.
- Utilize mulch to reduce soil splashing.
- Stake or trellis plants to reduce contact with the soil.
- Practice good crop rotation.
- Accurately identify the problem. You can only treat it appropriately if you know what the problem is.
- Using fungicides appropriately. Fungicides may be used to protect new plant tissue and prevent pathogen infection and spread. Fungicide applications should always be used in combination with other management tactics. Remember to always read and follow pesticide labels.
More information about managing potential problems found on tomatoes in home gardens can be found in this article: Managing Tomato Diseases, Disorders, and Pests.
Growing in Containers
Tomatoes are great candidates for growing in containers (Figure 9). Containers can be used when space is limited, a suitable full-sun location can only be found where a garden cannot be established (like a patio), or when you do not have access to an in-ground garden plot or raised bed.
Learn more in this article: Growing Tomatoes in Containers.
Seed Saving
Tomatoes are sometimes good candidates for seed saving. Seed saving allows gardeners to preserve heirloom varieties or their favorite plants from year to year.
It is easiest to save seeds from varieties that are open-pollinated (Figure 10). These seedlings come true to type as long as they are not allowed to cross-pollinate with another variety of the same species. Heirloom tomatoes are typically open-pollinated. In contrast, F1 hybrids are produced by crossing two specific varieties and planting the resulting seed. Seeds saved from hybrid plants will not produce progeny that resembles the parent plant, and, in many cases, they produce inferior fruit.
Learn more about harvesting, preparing, and storing tomato seeds from your garden in this article: How to Harvest and Store Seeds.
More Information
- Tomatoes (publication)
- Tomato Diseases and Disorders (publication)
- Best Tasting Tomato Contest at the Iowa State Fair (video)
- Is a tomato a fruit or vegetable?
- Vegetable Planting and Harvesting Times
- Crop Rotation in the Vegetable Garden
Photo credits: Figure 1: istetiana/AdobeStock | Figure 2: Agnieszka/AdobeStock | Figure 3: bearok/AdobeStock | Figure 4: Shawn Hamilton/AdobeStock | Figure 5: FotoHelin/AdobeStock | Figure 6: encierro/AdobeStock | Figure 7: Cindy Haynes | Figure 8: Iowa State University Plant and Insect Diagnostic Clinic | Figure 9: Mstock/AdobeStock | Figure 10: Robert Sijan/AdobeStock