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How to Grow Tomatoes Indoors with Lights [A Quick Guide]

growing tomatoes indoors with lights 

Growing tomatoes indoors can be a rewarding (and delicious!) hobby, but it's important to provide your plants with the right amount of light to ensure they grow and produce fruit to the best of their ability. 

So, can you grow tomatoes indoors with grow lights? If so, what’s the best way to do it?

Let’s take a look.

How to Grow Tomatoes Indoors with Lights

Grow lights are artificial light sources that mimic the spectrum of sunlight and provide the necessary light intensity and duration for plants to grow. We have written about grow lights extensively here at Cavelights, from how to hang them from the ceiling in your indoor garden to how long should they be on for to provide optimal growth.

They are a popular choice for indoor gardening because they allow you to control the light conditions in your grow space, even if you don't have access to natural sunlight. 

Growing tomatoes indoors with artificial light also presents some advantages, such as being able to keep the space light longer than daylight hours alone, as well as being able to determine precisely how much light you want your tomatoes to receive.

Here are some tips for using grow lights to successfully grow tomatoes indoors:

Choose the right grow lights

Many different types of grow lights are available, including incandescent, fluorescent, and LED.

For tomatoes, it's best to use full-spectrum grow lights that produce a wide range of wavelengths, including red and blue light, which are important for photosynthesis and plant growth.

So, as a recommendation, the best light for growing tomatoes indoors would be a full-spectrum grow light.

Set up your grow lights

Place your grow lights about 12-18 inches above the tops of your tomato plants, and position them so that they directly shine down on the plants from above. Make sure the lights are switched on for 12-16 hours a day to provide the necessary light intensity.

NOTE: If you’re worried about the cost of leaving your grow lights on for 12-16 hours a day, don’t be. We have written about the cost of electricity for running grow lights here, but in short, we’re looking at less than $1 per day.

Monitor the temperature

Tomatoes need a consistent temperature of around 70-75°F to grow properly, and if the temperature ranges far from these values for a significant amount of time, the growth of your tomatoes will start to be affected.

So, if your grow lights generate a lot of heat, you may need to use a fan or air conditioning to keep the temperature in check, or adjust the distance between your grow lights and the tops of your plants.

Fertilize and water regularly

As with any plant, it's important to provide your tomatoes with the proper nutrients and hydration. So, you’ll want to use a good, non-harmful fertilizer, and be sure to ensure your soil is never dry to the touch.

By following these tips and using grow lights, you can successfully grow tasty, homegrown tomatoes indoors all year round.

Happy gardening!

Frequently Asked Questions

Will Tomatoes ripen under grow lights?

Yes, tomatoes will ripen under grow lights, much like they ripen under natural light, such as when grown outdoors.

In fact, many people use grow lights to start growing tomato plants from seeds indoors before then transplanting them outside, or to extend the growing season by continuing to grow tomatoes indoors during the winter months.

So yes, artificial grow lights are an alternative to natural sunlight, and will ripen tomatoes perfectly.