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How to Grow Winter Tomatoes

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Updated 9.28.24

If you’d like refreshing salads, sandwiches, and side dishes made with juicy, flavorful fresh tomatoes in the dead of winter, I’ve got good news. You can grow winter tomatoes. The idea is not as far-fetched as it seems.

With a bit of effort and planning, you can enjoy tomatoes year-round. Consider these three options for growing winter tomatoes.

1. Grow winter tomatoes indoors

If you live in climate with cold winters, growing winter tomatoes indoors is the most logical option. Inside, plants have protection. They are not exposed to cold and harsh elements.

Indoors, your main task is to replicate the best outdoor growing conditions.

Set aside a small area in your home for your plants. Naturally, you need to follow the usual tomato growing tips for watering, repotting, and fertilizing.

In particular, when you grow winter tomatoes indoors, pay attention to these factors:

• Light: tomato plants need at least 8 hours of sunlight a day. If you choose a bright location, such as a south or west-facing window, and set plants back from the panes. Windows get cold to the touch indoors when temperatures are cold outside. Or grow tomatoes indoors under grow lights to ensure they get the required daily quota.
• Room temperature: Tomatoes grow best at 75-85 degrees F (24 -30 degrees C). Choose an area of your home where you can keep plants warm. You can set aside a specific room and use a space heater, if needed. If you grow winter tomatoes under lights, then use a cool white fluorescent lamp, since light can heat surrounding environment to more than 90 degrees F which will prevent fruit from setting.
• Air movement: set plants in an area that is not drafty. Cold air movement shocks heat-loving tomatoes. Yet keep in mind that tomatoes depend largely on insects for pollination. Indoors, you need to help along the fertilization process. Once blossoms appear, brush tops of plants lightly to help distribute pollen. You can even hand pollinate tomato plants with a cotton swab. Or use a small fan to circulate the air to encourage pollination.

What are the best tomatoes to grow in winter indoors?

Choose smaller varieties. Because small fruit have less skin to ripen than large tomatoes, they ripen faster. Small size and quick ripening are helpful indoors where there may be limited light.

Choose short-season varieties. Tomatoes can mature in 55 days or up to 100 days, depending on the variety. Determinate tomatoes set their fruit earlier than indeterminates, which leads many gardeners to choose determinates to grow indoors. Indeterminates, on the other hand, produce steadily until frost. There are plenty of short-season indeterminates tomato varieties that reach maturity early. You could grow indeterminates indoors in winter and then transfer them into your garden. Bottom line: you have the best success growing indoor tomatoes in winter when you choose varieties that mature in 55-70 days, whether they are determinates or indeterminates. 

2. Grow winter tomatoes in a greenhouse or cold frame

If you have access to a greenhouse or cold frame, you have an excellent option for growing winter tomatoes. A greenhouse or cold frame’s walls let in plenty of light. But if you live in an area that receives less than 7-8 hours of sunlight a day during the winter, you need to get supplemental lighting so tomato plants can get their 8-hour quota.

Temperature is another matter. As with indoor plants, you should keep the greenhouse above 60 degrees but below 90 degrees F. Use a thermometer to track the temperature. If air dips below 60 degrees, then you can supplement heat. You can choose from many options – some low-cost or no-cost – including:

• Portable space heaters: calculate how much space you need to heat and choose a space heater that will provide enough output for your square footage. Know your fuel source as you select a model. Space heaters can operate on natural gas, electricity, or propane.
• Electric fan heater: also called a blow heater, this device circulates air by pushing it over a heating element, which can help with pollination as well as warmth.
• Bubble wrap: insulate your structure by placing bubble wrap over the windows, where it will let in light but create a barrier from the cold.
• Indoor compost pile: a hot compost pile heats up to an internal temperature of 130-155 degrees F to break down yard and kitchen waste. An active hot compost pile in the corner of your greenhouse can give off heat your tomato plants need. 
• Passive solar heating: paint plastic soda bottles or milk jugs black, fill them with water, and set them near the windows to absorb heat during the day and radiate it during the night.

If you grow winter tomatoes in a cold frame, be sure it has enough height enough to allow plants to mature.

What are the best tomatoes to grow in a winter greenhouse?

You can grow any type of tomato in a greenhouse. Bush tomato varieties tend to grow outward and take up a lot of valuable floor space. They are a good choice for shorter cold frames. Indeterminate varieties, when staked, grow upward, and make best use of the vertical space. They are favored for winter greenhouse tomatoes.

3. Grow winter tomatoes outdoors (in mild climates)

Some gardeners have no worries about frost or freezes. You have a year-round gardening window. And to be honest, the rest of us are a bit envious.

You know that you’re among them when your overnight temperatures rarely fall below 50 degrees F (10 degrees C). If that’s the case for you, then growing tomatoes in winter outdoors becomes an exercise in choosing the best varieties.

But you need to have frost protection on hand in the event that temperatures go rogue. Individual plant covers, row covers, self-standing water tubes (like Wall-O-Water) – even sheets, blankets, and tarps – can safeguard your outdoor tomato plants in winter during a cold snap. 

What are the best tomato varieties to grow in winter outdoors?

Choose tomatoes for cold climates
The best tomatoes for cold climates are short- to mid-season tomatoes. That’s to say, they set fruit in cooler temperatures – and in many cases, their fruits reach maturity in the shortest number of days possible.

Choose small-fruited tomato varieties
Even if your weather is mild during winter, chances are good that temperatures are cooler than regular growing season. Large tomatoes often turn watery and mealy in cool weather. That’s why it’s a good idea to choose small-fruited varieties – like cherry tomatoes, plum tomatoes, and patio tomatoes – to grow outdoors during winter.
https://www.tomatodirt.com/cool-tolerant-tomato-varieties.html

One extra tip for growing winter tomatoes

Plan ahead. Few nurseries, garden centers, and online vendors offer tomato plants or seedlings for sale during the off season. You can take cuttings from your indeterminate tomato plants at the end of the regular growing season, root them, and plant them indoors in the winter. Or you can order seeds and start winter tomatoes indoor just as your regular summer season ends.

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