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Tomatoes are a great source of important nutrients, like vitamin C and potassium. While tomato season usually lasts from May to October, you can enjoy this crop year-round by growing tomatoes indoors!

To grow tomatoes indoors, you’ll need to keep them in a location with a temperature above 70 degrees Fahrenheit. Your tomatoes will also need at least 8 hours of sunlight per day. In addition, you’ll need basic supplies, like pots, potting mix, and plant stakes. 

If you start a tomato plant indoors, and you give the plant the care it needs, it should continue to produce fruit throughout the year. With the right supplies and growing methods, your indoor tomato plants should be a big success!

Growing Tomatoes Indoors

To successfully grow tomatoes indoors, you’ll need to create an environment that mimics the conditions that tomatoes need outdoors. 

This means finding a warm, sunny location in your home to plant your tomatoes. 

In order for tomatoes to produce fruit, they need at least 6 to 8 hours of sunlight per day. 

However, you’ll get better results if your tomatoes receive more than 8 hours of sunshine.

Temperatures around 70 to 85 degrees are ideal for tomatoes during daylight hours, while temperatures between 60 and 75 degrees are best in the evenings. 

While you can bring tomato plants indoors, you may get better results if you opt to grow your plants from seeds. 

Once you’ve found the right spot for your tomatoes, you can plant your seeds in a starting tray and wait for them to sprout. After the plants have sprouted, you can transfer them to a large pot, making sure that the plants get the sunlight and water they need. 

As the plants grow, place stakes in the pot to support the vines. 

Most types of potting soil are suitable for tomato plants.

To keep your tomatoes healthy, fertilize the soil every two weeks. 

Alternatively, you can grow them without soil using a method known as hydroponics. 

Check out our complete guide on how to grow hydroponic tomatoes.

Whether you grow your tomatoes with or without soil, it’s best to harvest the plants before they’re fully ripe to prevent cracking. 

Best Tomatoes to Grow Indoors

The height of tomato plants can vary significantly based on the variety of plant you choose. 

When growing tomatoes indoors, it’s best to stick with smaller tomato plants that are suitable for indoor growing. 

Dwarf and micro-dwarf tomato plants are a great option when growing tomatoes indoors. Typically, dwarf plants are between 2 and 4 1/2 feet tall and continue to produce fruit year-round. Popular varieties include Tiny Tim, Sweet Scarlet, and Florida Petite. 

In addition to considering the size of a tomato plant, it can be helpful to look at the plant’s other characteristics and needs. 

For example, Red Robin tomato plants can thrive in low-light indoor environments and tend to produce crops very quickly. 

Growing Tomatoes Indoors with Artificial Light

Ideally, tomatoes should get between 8 and 10 hours of sunlight. 

Without sunlight, plants can’t produce chlorophyll, which they need to survive. 

See what happens when a tomato plant gets too much sunlight

If you can’t give your tomato plants the light they need indoors, you’ll need to use some sort of artificial light source. 

Compact fluorescent lamps (CFL) are a small and efficient light source for indoor plants like tomatoes. Another great option is LED lighting. Full spectrum LED lighting is able to imitate the light of the sun, making it a fantastic option for plants. 

When you grow tomato plants with artificial lights, it’s important to monitor the plants closely. 

If you notice that your plants are growing pale, or if they are starting to yellow, that’s a sign that they’re not getting enough sunlight. 

You may need to add more lights or use more powerful lights that can meet the needs of your plants. 

Since artificial lights give off heat, you’ll also want to measure the temperature of the room. 

It’s best to keep tomatoes at temperatures between 70 and 85 degrees during the day and temperatures of 60 to 75 degrees at night.

Growing Tomatoes Indoors on a Windowsill

Growing plants on a windowsill can be a fantastic option if your space is limited! 

Since you’ll have limited space, it’s best to choose a small tomato plant, such as Micro Tom or Vilma tomatoes. 

South-facing windowsills provide lots of sunlight, which makes them a good spot for tomato plants. Place the tomatoes in a small pot and fertilize or water the plants as needed. Trim your plants as they grow to keep them from outgrowing their pots. 

Tomatoes need at least 6 hours of sunlight per day, but will thrive if they get 8 to 10 hours of sunlight each day.

Before you grow tomatoes on a windowsill, you should make sure that there aren’t any obstructions that could keep your plants from getting the sunlight that they need. 

Make sure that you choose a pot that fits comfortably on your windowsill. 

If the pot isn’t secure, it could get knocked over, which could put your tomato plants at risk. 

You should also make sure that the temperature around your windowsill is suitable for tomatoes. 

It’s best for tomatoes to be kept at a temperature between 75 and 85 degrees during the day and at temperatures between 60 and 75 at night. 

Growing Tomatoes Indoors in Winter

As long as your tomatoes get plenty of sunlight and are kept at the right temperature, you can successfully grow them during the winter. 

However, you should keep in mind that your tomato plants won’t produce new crops if the plants don’t get the sunlight and warmth that they need. 

Tomatoes need a minimum of 6 to 8 hours of sunlight per day. 

If necessary, you can use lamps that mimic sunlight. 

Plants must be kept at temperatures above 55 degrees and thrive at daytime temperatures between 70 and 85 degrees. 

At night, they can be kept at temperatures between 60 and 75 degrees.

Heat lamps and heat mats are both great ways to give tomato plants extra warmth on chilly days. You can also use a programmable space heater to warm up the room when temperatures drop. Since there are fewer hours of sunlight in the winter, you may also need to use an artificial light source. 

If there’s not enough humidity in your home, you can add more moisture to the air by placing a humidifier in the same room as your plants. 

Sunlight is limited in the winter, and if the leaves of your plants are dusty, it will be even harder for your plants to soak up all of the sunlight that they need. 

That’s why it’s a smart idea to clean the leaves of your plants and keep them dust-free. 

While you shouldn’t overwater your plants, you may find it helpful to use warm water rather than cold water when watering your plants during the winter. 

Plants tend to do well in humid environments, which is why it’s a good idea to keep your plants in a humid location. 

How to keep tomato plants alive during the winter.

Pollination for Indoor Tomatoes

Even though tomato plants are self-pollinating, pollen can get stuck inside the flower of the plant. 

When plants are outdoors, that pollen is removed by bees or swept away by the wind. 

However, if you’re growing tomatoes indoors, you may have to find a way to remove the pollen yourself. 

To knock pollen loose, place an electric toothbrush beneath the stem of any flower that’s just started to open. Keep the toothbrush in place for around three seconds. You should repeat this process for every new flower that opens on the plant. 

Ideally, you should spend about three days removing loose pollen from the flowers of your tomato plant. 

Conclusion

As long as you give tomato plants the care that they need, it’s possible for them to thrive indoors. 

Use these tips for growing tomatoes indoors so that you can provide your plants with everything that they need. 

Greg Volente

Greg Volente holds a Naturalist Certificate from the Morton Arboretum, worked for The Nature Conservancy leading environmental education programs and doing natural areas restoration, and worked in the soil science research & testing lab at Michigan State University. Besides gardening, he's an avid wildflower enthusiast, and loves botanizing, hiking, and backpacking.