A favorite tomato plant can be hard to toss in the compost heap at the end of the season, so you may be wondering, "Are tomatoes perennial?" Saving a tomato plant from one season to another isn’t common and comes with some challenges but it can be done. You won’t get fruit in the winter—it’s not tomato season after all—but you can keep the plant going so you can get a harvest the following growing season. Use these tips and methods to overwinter your favorite tomato plants.
Are tomato plants perennial?
Perennial plants come back year after year. They survive months of cold temperatures in winter, usually after their stems die back to the ground, then grow back from their roots to flower and fruit the following season.
Tomato plants hail from tropical regions of South America. In their native environment, they return reliably every year. The types of tomatoes we grow for BLTs, salsas, and salad toppers today were bred and selected for their fruit. Any minor winter hardiness they once had was lost in the breeding process, so tomatoes are grown as annual plants in home gardens. However, if protected from extreme cold, these plants can be kept alive from year to year.
What Is a Perennial?
A perennial is a plant that can grow for several years, as opposed to an annual plant that completes its life cycle (seed to seed) in the span of a single year.
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Tips for Overwintering Tomatoes
Tomatoes can survive through winter when brought inside and given some TLC. Before attempting to overwinter a tomato plant, keep these key concepts in mind to increase your chances of success.
The 1. Start with a healthy plant.
It is only worthwhile to attempt to overwinter a perfectly healthy tomato plant. Plants stressed, even minorly, by fungal diseases, leaf spots of various sorts, and insect pests are not in top shape and will likely not withstand the challenge of growing indoors. It is tricky to grow a disease-free tomato plant into September or October when it is time to transition indoors. But don’t make exceptions, only overwinter healthy plants.
The 2. Determinate plants overwinter best.
Tomato plants that grow to a certain height, then flower and fruit all at once have what's known as a determinate growth habit. Popular determinate tomato varieties include ‘Roma,’ ‘Bush Early Girl,’ and ‘Tumbler.’ Determinate plants have a better chance of overwintering than their indeterminate relatives. Indeterminate tomato plants continue growing, flowering, and fruiting over the course of their life. This ongoing growth makes it tricky to successfully overwinter.
The 3. Don’t expect fruit.
Tomato plants that flourished outside in the summer will not produce fruit in winter. Lack of heat, bright light, and pollinators squelch fruiting. The goal when overwintering tomatoes indoors is to simply keep the plants alive so they can fruit again in the following summer.
The 4. It’s a fun experiment.
Considering that starter plants are available for less than a dollar in spring, or you can grow your own seedlings for a few pennies, overwintering tomato plants isn't economical. And even with the most diligent care, a tomato plant may not withstand indoor life. Think of it more as an experiment to see if you can successfully overwinter a tomato.
How to Overwinter Tomatoes
There are two ways to overwinter tomato plants indoors without the help of a fully functioning greenhouse. Both methods are most successful when you begin with a completely healthy, determinate tomato plant that is growing in a container. Don’t try to transplant an inground tomato plant to a container for overwintering. The stress of transplanting a large plant may kill it.
Cool Environment Method
At the end of the outdoor growing season, move the container-grown tomato plant inside to an area that is between 40 and 55°F—an unheated garage or basement might work well. Place the pot under a grow light that provides light about 18 hours a day. Cut the plant back by half or so after it has acclimated to the indoor conditions. The plant will not grow much but will stay alive until the next growing season. Water the tomato plant as needed to maintain moist, but not wet soil.
Warm Environment Method
When nighttime temperatures drop to 55°F, move the container-grown tomato plant inside to a warm location—the ideal room temperature is 70 to 80°F. Place the container in a bright location such as a south- or west-facing window. Add a cool-white florescent light overhead, placing it 3-6 inches from the top of the plant. Plan to water the actively growing plant frequently. The best varieties for warm environment overwintering are types that grow just 1 to 2 feet tall. Try ‘Tiny Tim,’ ‘Micro Tom’, ‘Terenzo,’ or ‘Lizzano.’