Growing Tomatoes in Winter

By Taun Beddes | February 27, 2015

By: Taun Beddes, USU Extension horticulturist,

Most people would love to eat freshly grown tomatoes year round. Though tomatoes can be grown in the winter in a greenhouse, this can become expensive with the costs of heating and supplemental lighting, in addition to the cost of the greenhouse. The most likely option for hobbyists who want homegrown tomatoes throughout the year is to grow them in containers indoors. Consider this information.

  • Since most tomato varieties suitable for indoor use are only available as seeds, it is important to learn the basics of starting seeds indoors. The University of Minnesota has a helpful fact sheet available at: Starting Seeds Indoors. Since the tomato plant will be grown indoors, planting dates can be disregarded.
  • Smaller tomato varieties are best suited for indoor growing. These often only grow 1 to 2 feet around. A few varieties that may work well include Tiny Tim, Micro Tom, Terenzo or Lizzano. These seeds can be found online.
  • For growing, choose a bright location such as a south or west-facing window to maximize the amount of sun the tomatoes receive. The window should not be drafty. Temperatures below 50 degrees can harm tomatoes, and temperatures above 90 degrees may inhibit fruit set. Grow tomatoes under a cool-white florescent light. If using compact florescent bulbs, make sure they are at least 100 watt equivalent or greater. Make sure the tops of the plants stay within 3-6 inches of the bulbs. Adjustable desk lamps or inexpensive shop light fixtures suspended from chains are commonly used lights. It is not necessary to purchase more expensive, specialized grow lights or systems.
  • Make sure the container is large enough to accommodate the root system. For the smallest varieties, a 1-gallon pot is sufficient. For larger varieties, choose a 2 or 3-gallon pot, and note that it is better to have a pot that is too large rather than one that is too small. Additionally, as long as the growing container has drainage holes, the material it is made from is less important.
  • Choose a good peat moss-based potting soil for indoor plants. Never use soil from the yard. Fertilize with a well-balanced houseplant fertilizer, either granular or liquid, and follow the package instructions. Be careful not to over water, and allow the soil to dry out moderately between irrigations.
  • A large plant that is well cared for will likely produce more, but may require more maintenance. The smaller varieties are more of a novelty and are less work, but will likely only produce enough fruit for an occasional salad or sandwich. At any rate, tomatoes in the winter can be a delicious treat and can also help brighten up a dreary winter home.