Ask the Master Gardener: Tips for growing tomatoes and dealing with pesky fungus gnats

What tomatoes are most suitable for growing in containers? What do container-grown tomatoes require for success?

With so many varieties of tomatoes available, the selection of a variety that will adapt readily to being grown in the more limited space of a container can be daunting! In general, small- to medium-sized tomatoes adapt best to these conditions. In addition, a determinate tomato is better than an indeterminate variety, because determinates do not grow so large as the indeterminate types.

The varieties to look for vary, but look for cherry, grape, salsa and paste type tomatoes, as well as slicing or sandwich types. Most of these are determinate plants that will grow to a certain size. Checking plant labels should provide information on type of tomato, growth type, and ultimate size of the plant. Large tomato varieties, such as Big Boy or Beefsteak, are not as suitable for containers as they are indeterminate types and will continue to grow until frost. The root system of the larger varieties require much more room for their larger roots, thus require a much larger container, as well as more water and fertilizer.

Selection of the proper container for your plant is also important; the bigger, the better. A smaller container will require more frequent watering and fertilizer. A 5-gallon bucket or a 10-gallon container are both suitable. Cattle tubs, the type used for mineral supplements, are even better if you have access to these and enough room for a larger container. The container should be at least 10 to 12 inches deep. Whatever container used will need adequate holes in the bottom. Tomatoes require full sun, at least six to eight hours a day, as well as frequent watering and regular fertilizer. Plants should be watered at least once a day, preferably in the early morning; however if the weather is hot and/or windy, twice a day watering may be required.

What is the difference between determinate and indeterminate types of tomatoes? Are there determinate and indeterminate potatoes?

Determinate tomatoes will grow to a certain size, then stop; all fruit will be produced in a few weeks, with no more production after that. Indeterminate varieties will continue to grow until frost, continuing to blossom and set fruit, thus a much longer growing season.

Tomatoes and potatoes are very close relatives, so it should be no surprise that there are also determinate and indeterminate potato varieties, with much the same growth patterns as tomatoes. Determinate potatoes will produce a single layer of potatoes, while the indeterminate varieties will continue to produce potatoes for a longer period of time.

What is a simple and safe way to eliminate fungus gnats in my house plants?

A solution of one part hydrogen peroxide to four parts water used to drench the soil will kill the larva in the soil. This solution works best on dry soil rather than wet. The adults will not be killed by this, but they are very short lived and should soon die out.

Readers can pose questions or get more information by calling 417-874-2963 and talking to one of the trained volunteers staffing the Mas­ter Gardener Hotline at the University of Missouri Exten­sion Center in Greene County located inside the Botanical Center, 2400 S. Scenic Ave., Springfield, MO 65807.