Gardener’s Guide: How to Grow Tomatoes Indoors

Everyone loves a juicy, ripe tomato slipped onto a turkey sub or diced and simmered for fresh pasta sauce. While tomatoes are summer fruits and do best in hot, sunny weather, this doesn’t mean that gardeners have to relinquish their rights to this sweet summer staple in the winter. Growing tomato plants indoors can be just as easy, fun, and rewarding as growing them outdoors. While your harvest won’t be as large, you’ll still have access to fresh tomatoes for those turkey subs weeks after Thanksgiving. So if you want to know how to grow tomatoes indoors, keep reading! 

Seed Germination Method A

Growing your tomato plants from seeds isn’t nearly as difficult or time-consuming as you would imagine. The following traditional method of seed germination takes just 1-2 weeks.

  1. To get started, buy a packet of tomato seeds; potting soil; and small containers from your local nursery. You will want to plant two seeds per container in case some seeds do not germinate.
  2. To plant your seeds, fill the containers with damp potting soil. (Here’s a great article about potting soil if you’re not sure which to get.) 
  3. Eyeball or measure the size of your seed and then multiply by three. This is how deep you will need to place your seed in the soil.
  4. Once the seeds are planted, place the containers in a warm, dry place. For faster germination, you should add a source of heat to the bottom of the container, such as a heating pad covered with a towel. Or you can place the containers on top of the refrigerator.
  5. Once they have germinated and their roots are visible, you can plant your seeds.

Seed Germination Method B

Another method of seed germination, one researched and conducted by the engineers at xVirity, takes four days and uses no soil. Instead, all you need are shot glasses (you can substitute with a similar container), paper towels, water, and a bottle of xVital, xVirity’s nitrate water fertilizer.

  1. To begin, place the paper towels within the shot glasses. Then place the seeds on the paper towels.
  2. Create a solution using 75 ml of xVital and 25 ml of water (75% xVital and 25% water).
  3. Soak the seeds in this solution for 24 hours.
  4. After 24 hours, extract the seeds from the solution, dry, and place on a paper towel. You can also use a heating pad or place them on top of a refrigerator, as in the previous method.
  5. After four days, plant the germinated seeds in containers filled with damp potting soil following the guidelines above.



As seen above, using a mixture of xVital (NOX) with water results in quick seed germination. While the seeds germinated with lower concentrations of xVital resulted in increased sprout length, the seeds germinated with 75% xVital and 25% water grew the fastest in soil, as seen above.

If you are growing a larger type of tomato, you will want to re-pot your seedlings into a bigger container. Whichever container you use, make sure it has good drainage so you don’t drown your plants.

Growing Tomatoes Indoors

Now that your seedlings are settled in their pots, you can begin the process of growing your tomato plants!

It is best to keep tomato plants near a window where they will receive full light at least eight hours a day. If it’s cold by the window, place your plants in a sun room or other living space that receives a lot of light. Make sure the room is at least 65 degrees Fahrenheit.

Tomatoes need moist soil, so make sure you water regularly. You can also add wood shavings to your soil to help the plants absorb more water. Tip: when you water, make sure you direct the water source toward the soil and not the leafy part of the plant. This will help prevent disease.

You will want to feed your plants regularly to make sure they are receiving enough nutrients. Choosing fertilizer is often difficult, as there are so many options to choose from. Organic and natural fertilizers are always the best option for those who value environmental and health safety. Many organic fertilizers, however, can be toxic to pets. For instance, bone meal and other organic fertilizers made from animals can make dogs sick.

For a fertilizer that is safe, ecofriendly, and effective, use xVital. Our fertilizer contains just two ingredients: nitrate and ionized water. Not only does it provide essential nutrients to plants, but it also prevents root rot and replenishes plant growth and color.

To use xVital on your tomato plants, simply apply it to your soil during the vegetative stage. Before your plants begin to flower, apply xVital again with an increased dose. Up the concentration one last time and apply after the plant’s first fruit formation.

If you need help determining how much fertilizer to combine with water, simply use our online ratio calculator. For further directions, see our online manual.