Hero Image

Growing Tomatoes

Types and Varieties

Determinate tomatoes are also called bush tomatoes. They grow in a bushy fashion to between 3-5 feet and produce tomatoes for a period of 4-6 weeks. These include canning and many early ripening varieties.

determinate tomato

Indeterminate tomatoes grow and set fruit all summer until killed by  frost or disease. Unless supported by sturdy trellises, cages, or stakes, indeterminate plants tend to sprawl on the ground, leaving the fruit susceptible to rot where it comes in contact with the soil. Most commonly grown large fruit tomatoes are indeterminate.

Container Varieties

Container varieties are adapted to all three zones of the state. Midget, patio, or dwarf tomato varieties are ideal for small-space gardening, as they have very compact vines and do best when grown in 5-gallon (20-l) or larger containers, or in large hanging baskets. Some produce fairly large fruit, but the fruit are often of poorer quality than fruit from standard-sized plants. Container varieties are usually short-lived, producing their crop quickly over a short period.

tomatoes growing in container

Some varieties that do well in the Central Valley include Sungold Juliet Celebrity Lemon boy San Marzano and Roma

Tomato Pests and Disease

An ounce of prevention can save you from a host of problems. 

  • Clean up garden beds at the end of the season removing debris.  
  • Remove weeds from garden beds a few weeks before planting. 
  • Plant disease resistant varieties.
  • Keep tomato plants off the ground using cages or stakes. 
  • Mulch tomato plants well.
  • Avoid overhead watering and over-crowding of tomato plants.
  • Water tomatoes consistently when top 2" of soil is dry.

Tomato Diseases

Early Blight is a common leaf spot caused by the fungus  Alternaria solani. Dark brown spots with yellow haloes appear on the leaves, and concentric rings can be seen in the spots under bright light. it can also infect stems and fruit often starts at the bottom of the plant and moves upward. Cool humid weather or overhead irrigation  encourage Early Blight so avoid getting water on the leaves. Mulch well around plants and clear away all dead or infected plant materials each season. Picking off infected leaves may slow the progress of the disease.

early blight damage
early blight damage

Speck and Spot are bacterial diseases with similar symptoms, causing small black specks or patches on leaves stems and fruit. They have a water-soaked appearance of the spots and that the spots don’t cross the larger veins. Like Early Blight  they are spread by water and can be prevented and controlled in the same manner as for Early Blight.

tomatoes damaged by late blight
tomatoes damaged by late blight
Late Blight is a fungal disease caused by Phytophthora infestans most famous for he Irish potato famine. It is just as serious in tomatoes. it causes dark green to purple brown water-soaked spots that grow quickly on leaves and stems. Sometimes there are whitish powdery spore on the underside of leaves. Fruit turns brown but stays firm. It thrives during high humidity and mild temperature in the 60-78 degrees F Once it gets started it can kill a plant quickly and spread to other tomatoes, peppers and potatoes. Control by avoiding sprinkler irrigation very dense planting, or things that keep humidity high. Mulching may help prevent initial infection. Remove volunteer potatoes or tomatoes, and clean up debris at the end of the season

Fusarium Wilt is caused by a soil-borne fungus (Fusarium oxysporum) which infects the roots and stems of tomatoes. Leaves turn yellow and wilt without spots, and brownish streaks creep up the inside of the main stem and into the branches. symptoms are worst in warm weather, especially as first fruits are getting large. It is usually fatal.Fusarium can survive a long time in the soil and it is easily spread by shoes, tools etc. The usual solution is to grow resistant varieties, look for an F or FF on the variety label. Cleaning up all tomato debris, including old roots and solarizing soil may help.

Fusarium Wilt
Fusarium Wilt

Verticillium Wilt (Verticillium dahliae) is similar to Fusarium Wilt and it can be difficult to tell the apart, though Verticillium prefers cool temperatures. It is managed in the same ways as Fusarium Wilt. Varieties resistant to it carry a  V on the label.

Powdery Mildew can appear in late summer or fall as nights cool, but rarely causes much damage. Irregular yellow blotches with a faint coating of white powder form on the leaves and causes brown dead patches.No control is needed on mature plants but sulfur dust provides good control on young or severely affected plants.

Tips on Growing Tomatoes

 

What do Tomatoes Need?

Water- Consistent watering is important as it helps to prevent problems like blossom end rot and fruit cracking.  Soil around new plants should be kept moist for the first few weeks. Established plants should be watered when the soil is  dry to about 2-3 inches. 

Fertilizer- Healthy tomato plants should not need any fertilizer until after they have set fruit. At fruit set, plants can be side-dressed with nitrogen fertilizer every 4 to 6 weeks, following instructions on the product label. To side-dress, place fertilizer at the sides of the growing plants in shallow grooves or on the soil surface, then thoroughly water the fertilizer into the root zone to assure effective use by the plants. If manure or preplanting fertilizer was used in preparing the planting site, reduce the rate of fertilizer application by one-half. Avoid applying more fertilizer than necessary, as excess nitrogen may be leached past the root zone and cause contamination of the groundwater supply.

Support- Tomatoes of all type need a strong support such as a cage trellis or stakes to keep plant upright and off the ground. Cages work well in the central valley heat. They can be made easily from hog wire with holes large enough to reach through to harvest.

tomato cages

Harvest- For best flavor, harvest when fruit are at full color for the variety—rich red, orange, or yellow. Ripe tomatoes should be stored at 55 to 70 degrees F (12.8 to 21.1C) to maintain their fresh, ripe flavor.

tomatoes in bowl
Lengthy refrigeration causes flavor loss and browning discoloration of fruit. Toward the end of the season, there are usually some whitish- green, full-size tomatoes still on the vines. You can pick these tomatoes and store them at 70 degrees F (21.1 C) to ripen. Place harvested immature tomatoes in a shaded location to further ripen the fruit. Light is not necessary for ripening immature tomatoes.
San Marzano FEB

For more information on growing tomatoes visit ANR publication 8159 -Growing tomatoes in the home garden

Abiotic Disorders and Pests

Abiotic Disorders 

Flower Drop and fail to set fruit can be caused by a number of factors including night temperatures below 55 o F, too much shade, excess nitrogen fertilizer, smog, or plants set out too early in the spring. The most common problem in our area though is daytime temperatures above 90F. When temperatures cool they will set flowers again. Tapping on blossom stems 3 times aweek when flowers are open may improve pollination and fruit set.

Blossom End Rot
Blossom End Rot
Blossom End Rot  is a water soaked spot on blossom end of fruit that enlarges and darkens, becomes sunken and leathery. This is caused by calcium and water balance, aggravated by high soil salt content and fluctuating soil moisture. Maintain even soil moisture. Amend soil with organic matter to improve water retention. If soil is deficient in calcium amend with gypsum. 

Solar Yellowing Green Shoulders or Sunburn are all caused by high temperatures and overexposure to sun. They are prevented by maintaining plant vigor to produce adequate leaf cover, not pruning and providing partial shade during hours of most intense sunlight.

Sunburned tomato

Tomato Pests

Aphids can be a problem but a handful of them won’t hurt a healthy plant but if shoots are covered with them or new leaves are curling blast them off with a strong jet of water or crush by hand.

Cutworms are green or brown caterpillars that curl into a C shape when disturbed. They eat young plants at the soil line at night. Control by hand-picking at night. Protect seedlings with cardboard collars or toothpicks inserted close  and parallel to the stems.

hornworm
hornworm
Hornworms are voracious eaters of tomato plants and fruit. They are rather large (1”-4”) green caterpillars with a prominent horn on the tail end. They will eat leaves, stems and fruit and can strip young plants entirely. mature caterpillars drop to the ground and pupate in the soil over the winter.

Fruitworms also known as corn earworms  are pale green or brown, one inch long. They burrow into the stem end of tomato fruit.

Control both these caterpillars by hand picking them in the early evening, when most active is most effective.  Organic Bacillus thuringiensis or spinosad sprays can help with control. See IPM for precautions and application tips. 

Stinkbugs can cause corky white patches under the skin of ripe tomatoes that don’t peel easily when cooking or canning the fruit. To control them Hand-pick stinkbugs or snip them with garden shears or drop into buckets of soapy water. Eliminate weeds around garden beds at least two weeks before planting.

stink bug
stink bug

Snails and slugs can be a problem particular if plants are on or near the ground. They can eat large chunks of ripening fruit if they have easy access but rarely bother foliage on mature tomatoes. Prevent problems with snails by using cages or stakes to keep them off the ground.

 For more information on tomato pests and diseases visit the UC IPM page on tomatoes