Grow Tomato Plants from Seed!
Do you want to learn when to plant tomato seeds? Or how to grow tomatoes from seed? It is a really fun, rewarding experience, and it is easier than you might think!
In this step-by-step guide, we will walk you through the process of growing your own tomatoes from seed.
We will not only discuss when to plant tomato seeds but also everything from choosing the right soil, how to transplant, and beyond.
There is even a video of me planting the seeds. By following these simple instructions, you can successfully grow tomato plants that will produce delicious fruit in your garden!
When to plant tomato seeds
This really depends upon your local weather conditions and sometimes the variety of tomatoes you are starting from seed.
When is your average last frost date? Most often the recommended time frame is to start seeds 6 to 8 weeks prior to your average last frost date.
For most folks, you should plan on setting your tomato seedlings out two to three weeks after your final frost. I am a rebel and plant mine out sooner but I protect them.
This is for indoor starting. You can direct sow tomatoes outside as well but starting them ahead of time gives you a jump on fruiting.
Unless you have a really long growing season, planting outdoors from seed is usually not recommended.
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The Best Soil for Tomatoes
To plant tomato seeds, if starting indoors, use a sterile potting mix or seed starting mix. I often use my own DIY Potting Soil but sterilize it with boiling water poured through it.
But for most people seed starting mix is the way to go. Seed starting mix is widely available at many big box stores as well as at garden centers.
*FYI: I ran a test of seed starting mix vs regular potting soil and you may be surprised by the results, I shared that in another post.
Must you Use seed Starting mix?
An Experiment for Seed Sowing
We always hear that we must use seed starting mix for growing plants from seeds. But must we?
For soil conditions when starting tomato seeds outdoors see that section.
Starting Tomato Seeds Indoors
Next, you will need to fill a container with the seed starting mixture.
Sometimes I start with a shallow container for my seed starting but I pot up the seedlings once they get their true leaves so I don’t need anything deeper.
If you are planning on leaving the seedlings in the originating container for the long haul then use something deeper so the roots can grow well.
Place the tomato seeds on the soil, making sure that they are spaced an inch or so apart.
Press them into the soil and cover them with a thin layer of seed starting mix. Don’t overthink this, as long as you don’t plant too deep you are good. A good depth is 1/4 inch.
This is next step is optional but can help retain moisture, and that is top dressing with a touch of vermiculite. I show how I use it in the video at the end of this post.
Water the seeds gently, (I prefer bottom watering), and then place the container under grow lights and sometimes on a heat mat. (I share my setup here) Keep the soil moist but not wet.
get growing on a budget
Indoor Seed Start Light Set-Up
Indoor seed starting doesn’t need to be fancy or expensive. A simple setup will get the job done.
Growing Tomato Seeds Outdoors
Wait until the soil is warming in Spring for attempting to start tomato seeds out in garden beds. When starting seeds outdoors you will first need to prepare the soil. The best way to do this is by always building your soil.
healthy soil healthy plants
Build Organic Garden Soil
When you build your garden soil you can save a lot of money as you won’t need extra fertilizers and the healthier the plants means no need for pesticides.
Even if you have not been working on your soil just be sure to mix in organic matter, such as well-rotted manure or compost, to help the plants grow strong and healthy.
(note, planting tomato seed directly is usually reserved for longer growing season areas but if you want to try it, go ahead. What have you got to lose?)
Plant the seeds about 6 inches apart, you can relocate some if they all come up to give them room to grow.
Tomato Seed Germination Time
Tomato seed germination happens in 7 days to two weeks. I have had germination in as little as 5 days but timing depends upon the variety as well as the conditions you have them in.
Tomato Seedling
Once the seeds have their second set of leaves, you will need to start to fertilize with diluted organic fertilizer.
The seed starting mix is devoid of nutrition and the tomato seedlings will need some help. (if you have used potting soil then you can delay feeding)
Dilute the organic fertilizer (this is the one I love and use) to a 1/4 strength. As the seedlings grow you can decrease the dilution rate.
For example, after a couple of weeks make it 1/2 strength.
Once they have two sets of leaves you can move the tomato seedlings to a larger container. After repotting tomato seedlings be sure to keep the soil moist but not wet at all times.
Transplant Tomato Seedlings
When the plants are about 4 to 6 inches tall and the weather has gotten warm enough, you can transplant them into your garden or into a container on your patio.
Warm enough means the nights are staying above 50 degrees.
Plant them several inches deeper than seedlings were growing in containers. Provide strong supports or tall wire cages at planting time.
Mulch to provide even moisture retention; don’t overwater once fruit begins to ripen. Overwatering will leach out some of the flavors of your tomatoes.
Tomato plants need at least six hours of sunlight per day in order to produce fruit. Be sure to place them in a spot where they will get plenty of sunshine.
Fertilizing Tomatoes
If you have been building your soil as I suggested in an earlier post you won’t need to fertilize very much, if at all.
Adding some more compost is a great way to mulch your tomato plants after planting them as it aids in moisture retention but will also slowly feed your tomatoes.
If you do need to fertilize then the organic fertilizer I noted before works wonderfully as it feeds not only the plants but also the soil. You can use the general purpose or the Fruit and Flower.
It takes about two to three months to grow tomatoes from seed.
Leggy Tomato Seedlings
If your tomato plants don’t get enough light they will try to stretch for it. If growing under lights, as I suggest, move the plants closer to the lights.
Leggy seedlings are not the end of the world. When you pot them up to a large size pot, bury the stem up to the lowest leaves.
Some of my favorite varieties of tomatoes:
Cherry Tomatoes
Super Sweet 100 tomato is a tried and true winner in my garden. Super easy to grow for beginner gardeners and children. The name says it all, hundreds of the sweetest little tomatoes will be produced all season long. Here where I live it is widely available at garden centers so you may be able to find it.
Camp Joy tomato is slightly larger than what I consider a cherry tomato but it is fantastic to grow. The ping pong size tomatoes are perfect for salads, fresh eating, and a version of Caprese salad where you use the small balls of mozzarella cheese.
Sun Gold is a favorite of many but the one I bought at the garden center split easily on me but I may try growing my own from seed. Renee’s Garden seed description says this variety is resistant to splitting.
Heirloom Tomato Varieties
Brandywine is a tried and true favorite of many. The flavor is unsurpassed for slicing and eating fresh. (IMHO)
Costoluto Genovese, a fantastic tomato. Costoluto’s strong indeterminate vines grow tall and heavy with big crops of tender, juicy, rich red tomatoes. They have a crinkled appearance.
San Marzano tomato seeds can be found here and they are an old Italian variety that is highly treasured. San Marzano tomatoes make the thickest sauce and they taste great fresh as well!
Early to Bear Variety
Early Girl – I always include an Early Girl in my garden. We have a relatively short growing period and Early Girl always gives me tomatoes two full weeks before any other slicing tomato.
It also is the last to succumb to cold in Fall so it continues another week or two after the others are done. Though not as flavorful as other tomatoes, we still enjoy them and they taste better than store-bought.
Early Girl has always been available at our local garden center so I don’t start it from seed.
I show you how I plant tomato seeds.
