When Should You Start Tomato Seeds Indoors?

One of the most frequently asked questions I receive about seed starting is, “When should you start tomato seeds indoors?” Let’s take a look at tomatoes and how to start them from seeds.

If you plant to grow just a few tomato plants in containers or pots on your balcony or desk, you are better off purchasing plants from your local garden center or nursery. You will get better results and save money and time. If, however, you wish to plant many varieties of tomatoes in a large garden, then starting from seed is the most economical approach.

Starting Tomato Plants from Seeds

Tomato plants can be grown from cuttings or from seeds. You can also purchase plants in pots or containers and transplant them into your garden.

Most serious gardeners (and tomato lovers) grow tomato plants from seeds. Seeds provide you with an enormous selection of tomatoes. You can choose heirloom or hybrid tomatoes, cherry tomatoes or giant beefsteak tomatoes, or colorful red, purple, yellow, striped, and even green tomatoes.

Garden centers are limited by space and general local demand to a select few varieties of tomatoes to grow or purchase for resale. The gardener who begins tomato plants from seeds is not limited by either. He or she can choose any seed to start indoors.

Timing Your Tomato Plants: When to Start Seeds

1. Purchase the desired tomato seed variety.
2. Look up your area’s gardening zone. You can find your gardening zone here.
3. Grab a calendar and circle the date of the last expected frost for your region on the calendar. That is the date when you can place mature tomato plants outdoors in the garden.
4. Flip over the seed package and look for the recommended planting time. Look for information on how many weeks the plant needs to grow before setting it outdoors. A good rule of thumb for most tomatoes is 8 to 12 weeks, from the time to plant the seed to the time you set the plants outdoors.
5. Now count backward 8 weeks from the circle frost-free date on your calendar. Put a star on this date.
6. That is the date when you can plant your tomato seeds!

How to Plant Tomato Seeds

Tomato seedlings need full, bright sunlight or artificial light to thrive. They need clean containers such as a seed tray or pot. Clean the container with a solution of 9 parts water to 1 part household bleach to prevent diseases such as dampening off from killing your seedlings. Mix the water and bleach solution in a tub or pail, soak the container for 10-20 minutes, then remove it and rinse it under plain water.

Use a seed starting mixture or a good bagged potting soil mix. Place it in the container. Take each seed out of the package and gently press it into the soil. The seeds should be about 1/4 of an inch below the soil level. Water them well and place the tray or pot under the lights. Keep the soil evenly moist until the seeds germinate, then water as necessary.

If you are growing a lot of seeds or varieties of tomatoes, label your pots and containers with the type of seedling and the variety name. Trust me on this, you won’t remember what you have planted. Label everything!

Keep your seedlings indoors until it is time to move them outside. Then gradually acclimate them to the outdoors. This is a process called hardening off. Bring the trays outside during the day and back inside at night. Do this for a week, then leave the trays continuously outdoors for a week. Make sure the seedlings are kept well-watered and be sure to take them back inside if there is any danger of a frost.

After two weeks of this TLC, your tomato seedlings should be ready to plant in the garden. When you plant tomatoes, there’s a little trick to get stronger, healthier roots. Peel off the bottom sets of leaves from your seedlings and plant the tomato stem well below the soil line. Tomatoes grow extra roots from their stems if the stems touch the soil and you will have a healthier, stronger root system.

Happy gardening and keep growing!