Learn how to grow healthy, tasty tomatoes all season long with these tips.
While tomatoes are the most commonly grown vegetable, they're also one of the most problematic. A wide range of pests and diseases can attack tomatoes, ruining your plants before you get to enjoy a full harvest. Here's help.
Tomatoes, like most vegetables, grow best in a spot with full sun and well-drained soil. They'll be more prone to disease if you plant them in heavy clay soil or shade. Also, it's helpful to plant tomatoes in a different part of the garden each year as diseases can build up in the soil.
If you have poor soil or don't have the option of planting your tomatoes in a different spot each year, try growing tomatoes in containers. Most tomatoes do really well in large pots filled with a potting mix designed for container-grown plants. Just be sure you have a big-enough pot -- at least 12 inches in diameter -- many tomato varieties can grow 6 feet tall by the end of the season!
From cherry tomatoes to heirloom, there are literally hundreds of tomato varieties on the market. Different types are best adapted to different areas. For example, the University of Florida has released varieties such as 'Solar Set' that thrive in hot, humid conditions. Other areas, such as 'Northern Delight', have been bred to produce fruit quickly and are best for short-season areas. Check with local experts, such as your county extension agent, for recommendations.
Another key to preventing disease problems is to select disease-resistant varieties. These will often have a letter, or series of letters (such as VFFN), on the plant tag or in the seed-catalog description. These letters stand for different disease strains.
Stressful growing conditions weaken plants and make them targets for disease. So make sure your tomato plants are well watered during dry spells and well fed during the season.
To help cut down on competition from weeds and to help the soil hold moisture better, spread a couple of inches of mulch over the soil surface. Mulch can also create a protective barrier that helps stop soil-borne diseases from splashing up onto and infecting plant leaves.
Wet foliage can encourage fungal diseases, so it's especially helpful to water your tomatoes with a soaker hose or drip irrigation instead of with a sprinkler or spray nozzle on your garden hose. If you have to water from the top of the plant, do so before noon so the leaves have plenty of time to dry before temperatures cool down at night.
Cracked Fruits: When tomato fruits crack open, the problem is usually that the plants are getting too much moisture and nutrients. Cut back on the water and fertilizer a bit and look for cracking-resistant varieties.
Fruits Have Dry, Dark Areas at the Ends: Dry, dark spots on the end of the fruits appear because of blossom-end rot, a condition caused by hot, dry conditions or fluctuating moisture levels. Keep plants well watered during hot weather and make sure they're watered consistently.
Old Leaves Have Brown of Black Spots: Early blight is a common disease that disfigures old leaves. Remove the leaves as soon as you see spots form; this may prevent it from spreading to the rest of the plant. Spreading mulch over the soil and keeping the leaves dry can also be effective preventive measures. Spraying with fungicide can help, too, but only if you spray before the disease takes hold. Early blight cannot be cured.
Old Leaves Have Pale Green Spots That Look Water-Soaked: This is late blight. Prevent the common fungal disease by removing infected leaves as soon as you see spots form. Other prevention techniques are to spread mulch over the soil, keep the leaves dry, and spraying with fungicide before the disease gets too bad. Late blight cannot be cured.
Leaves Turn Yellow Before Wilting and Turning Brown: Two common diseases -- verticillium and fusarium -- cause this symptom. Both are preventable. Remove infected leaves as soon as you see spots form -- this can prevent it from spreading through the entire plant. Also try spreading mulch over the soil, keeping the foliage dry, or as a last result, spraying with fungicide before the disease takes hold. Fusarium and verticillium cannot be cured.
Large Green Caterpillars That Eat the Foliage: Tomato hornworms can rapidly devour your prized tomato plants. Organic options are to squash or drop the caterpillars into a bucket of soapy water or to spray with Bacillus thuringiensis, a bacterium that attacks and kills caterpillars. Note: Several species of wasp will lay their eggs on the caterpillars. If you see a hornworm with the eggs, don't bother killing it. The wasps are already doing it for you.