How to Grow Indoor Tomatoes

You can grow indoor tomatoes during the off season and have a continuous supply of fresh tomatoes all winter long!

Advantages to growing indoor tomatoes

  • Taste. Fresh, vine-ripened tomatoes taste much better than store-ripened tomatoes.
  • Health. Fresh tomatoes grown indoors can be preservative-free.
  • Fun. Growing tomatoes indoors can satisfy your green thumb during the cold winter months.
  • Prep for spring. Indoor tomato plants provide the opportunity to take cuttings in late winter to give your spring tomato patch an early jumpstart.

Where to grow indoor tomatoes

There are three places to grow tomatoes indoors.

  1. On a windowsill. While a window is the easiest and cheapest place to grow tomatoes inside, make sure it faces south to allow enough light. Watch out for drafts to keep plants warm.
  2. Under grow lights. A controlled light source allows tomato plants to receive their needed 12-16 hours a day.
  3. In a greenhouse. A glass enclosure lets in plenty of natural light. With a reliable heat source in the greenhouse, plants can grow well.

    (Find greenhouse plans here.)

What you need to grow indoor tomatoes

Tomatoes need two things to grow successfully inside during winter.

Light
Indoor tomatoes require 12-16 hours of light a day. Even plants in a sunny window or in a greenhouse may need a few extra hours under grow lights during winter’s short days.
Heat
Indoor tomatoes grow best when the air temperature is between 65º-85ºF. If your house thermostat is set lower, your house is drafty, or your greenhouse isn’t heated, keep plants warm with a space heater or seedling heat mat.

What kinds of tomato plants should you grow indoors?

Cherry or plum tomato indeterminate varieties perform best indoors.

Why indeterminates? It can be tempting to choose compact tomato varieties to grow indoors because their size is, well, compact. But most compacts are determinate tomatoes, which produce a finite amount of fruit within a short time of about 2-3 weeks and then stop. Indeterminate varieties, on the other hand, continue to grow throughout the winter and will produce fruit in abundance. Never fear - you can choose indeterminate varieties that may not be labeled "compact" but won't create a jungle in your family room.

Why cherry or plum varieties? Small fruited plants (cherry or plum tomatoes) produce a large number of fruit and ripen quickly.

Best tomato varieties to grow indoors ...

Ways to start tomatoes indoors

Choose from three ways to get your indoor tomato plants started

  1. Start tomato seeds midsummer either at in a windowsill or under grow lights
  2. Root tomato cuttings from your summer plants
  3. Buy tomato plants mid-season



More on growing tomatoes indoors

Best indoor tomato varieties ...

How to take tomato cuttings to grow indoors ...

How to grow tomatoes on a windowsill indoors ...

Tomato greenhouse basics ...

How to identify and control indoor tomato pests ...

Tomato grow lights explained ...

Using fluorescent grow lights to start seeds, grow tomatoes ...

Fluorescent grow light systems to choose from ...

Growing indoor tomatoes FAQs: Frequently Asked Questions...

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