It’s no secret that I love growing tomatoes from seed. I’ve been growing tomatoes in my garden for years and have tried many different varieties.
Last year, I decided to grow more than 25 varieties in my western North Carolina clay soil and was really happy with the results.
All of them grew well, and I did like some varieties better than others.
In this post, I’ll share everything I know about growing tomatoes from seed.
I’ll share how I started the seeds, transplanted them, pruned the plants, fertilized them, and harvested them.
This post is all about growing tomatoes from seed.
Why You Should Absolutely Grow Tomatoes From Seed
You should grow your own tomatoes from seed because you’ll have access to hundreds of varieties of tomatoes. You’d never be able to have access to those varieties otherwise.
Sure, you could buy tomato plants at a big box retailer, but there are only a few varieties to choose from there.
You’ll find an Early Girl, Better Boy, a Cherokee Purple, and maybe a cherry tomato variety.
That’s it.
If you really want variety, growing tomatoes from seed will give you that variety.
Find out more about why you should grow your ENTIRE garden from seed in this post: 5 Reasons You Should Grow Vegetables From Seed in Your Next Garden.
What You'll Need to Grow Them (Material List)
Now that you’ve decided to grow tomatoes from seed, you’ll need to gather the materials you’ll need.
You need to start your seeds about 6-8 weeks before your last frost date in the spring for your planting zone.
To find out which planting zone you are in, go to: https://www.almanac.com/gardening/frostdates and type in your ZIP code to find your last frost date in the spring.
Once you have that date, just count back 8 weeks to determine when you need to plant your seeds. This way, your seedlings will be ready to plant after the threat of frost is passed.
You don’t want to start your tomato seeds too early. If you do, you’ll have to move the tomato plant to a bigger pot BEFORE you can put them in your garden. Having to do that wastes a ton of time, money, and resources..
Tomato Seeds
There are several great places to buy tomato seeds.
If you want to be able to save seeds from your tomatoes so that you can plant them in the future, be sure to plant “heirloom” or “open-pollinated” seeds. If that is less important to you, you can certainly look into hybrids.
There is nothing wrong with hybrids. In fact, many of my favorite vegetable varieties are hybrids. Hybrids are usually selected for beneficial traits like disease resistance or high yields, so there is definitely a place for them in your garden.
I grow about 80/20 heirloom/hybrids. Saving tomato seeds is important to me, so I do grow a lot of heirlooms. However, I do love how hybrids can be selected for attractive traits, so I’m always looking for a few good hybrids to try.
As a general rule, heirloom seeds will be less expensive than hybrids. If you are planning to sell the vegetables you grow, there will be many hybrids that you can grow that will give you a more predictable harvest than heirlooms.
My favorite places to purchase tomato seeds include:
Soil
You need light and fluffy soil to start seeds. Don’t try to use regular garden soil, topsoil, or other dirt. Those kinds of soil are way too heavy for the tomato’s delicate roots to grow into. Your seedling can be stunted and die trying to grow in heavy soil.
Look for a soil mix that is specifically referred to as seed starting mix. You can make your own by sifting regular potting soil through a regular kitchen colander to get out the larger wooden bits. Don’t throw those pieces away. You can put them in the mulch you have around your landscape plants.
Great seed starting mixes that I have used and recommend include: Purple Cow, Espoma, and Promix. I have used others, but they did not perform as well as these three. This season, I am using Promix.
Seedling Growing Containers
You can use whatever you have on-hand to start seeds, or you can purchase containers that are specially made for seed starting.
I wrote an article all about seed-starting containers, and it’s my most popular post on the blog. Check it out here to decide which containers you want to purchase: “Seed Starting Containers: Use These to Grow Your Best Garden Ever”
Whatever containers you choose, make sure there are drainage holes in the bottom of the container so the roots don’t rot.
Fertilizer
In my experience, you’ll need two basic types of fertilizer to get you through to the harvest of your delicious tomatoes. You’ll need a liquid fertilizer and a granular fertilizer.
We’ll use the liquid fertilizer to feed the seedlings right after they germinate. We’ll use the granular fertilizer when we transplant them into the ground or into the container that we plan to keep them in.
I recommend Vermisterra Worm Tea, Trident’s Pride Fish Emulsion Fertilizer, and AgroThrive organic liquid fertilizer.
When you transplant the tomato plant into the ground, you’ll add about a tablespoon of organic granular fertilizer into the planting hole, mix with the soil, then backfill the soil around the plant.
Then, every 6 weeks or so, you’ll side dress the tomato plants by sprinkling the same fertilizer on the ground around the plants and working into the top couple of inches of soil, being careful to not let the fertilizer touch the leaves or stem of the plant.
Plant your Seeds
When it’s time to plant tomato seeds, just moisten your soil, place the soil into your containers, then poke a hole about 1/4 deep.
Put a couple of tomato seeds in each cell, cover them with soil, then lightly press the soil down to be sure the seed is touching soil.
Water in the seeds, and you’re almost done! I like to add a very thin sprinkle of vermiculite to the surface of the soil after I water because it slows the growth of algae. It also helps maintain moisture on the surface while we wait till the seeds germinate.
Be sure to check the seedlings daily. Use a spray bottle to moisten the surface of the soil when it gets too dry.
Tomato seeds take about 7-10 days to sprout. If you have a heat mat to set them on while you wait, they will sprout faster.
Once they sprout, you need to put them in a VERY BRIGHT area. Areas that could work are a very sunny windowsill, a greenhouse, or under a grow light. If you use a grow light, make sure you maintain an inch or so distance from the light to the plant tops.
As your tomato seedlings grow, lower the seedlings or raise the lights. This way, you maintain a distance of around one inch from seedling to light at all times.
If you don’t give them enough light, the seedlings will stretch upwards in a desperate bid to get more light. This will stretch out the stems, making them weak. This is called being “leggy”.
There is some hope for leggy tomato seedlings because you can just plant the seedlings very deeply to cover up most of the stem. However, you really want to avoid leggy seedlings if at all possible.
Take Care of your Seedlings
Once your tomato seedlings have germinated, just keep them happy until it is time to plant them outside.
If both of your seeds in each cell come up, you’ll need to thin the smaller one after about 2-3 weeks of growth. This is difficult to do after you worked to get them to grow, but trust me that it’s the way to go. The remaining seedling will be much stronger for it, and that’s what you want. Once you get used to doing it, you won’t give it a second thought.
Water the tomato seedlings from the bottom once the tomato seeds have germinated. Watering from the bottom helps force the roots to grow deeper and stronger in order to reach the water, which creates stronger seedlings.
Fertilize them every 10 days with a half-strength liquid fertilizer. If you are using grow lights, they will need to be about an inch from the top of the plants, so you’ll have to move either the tomato seedlings or the lights on a regular basis.
Plant Your Seedlings Out in the Garden
Once you are past your last frost date, you are ready to put your seedlings into the ground!
Before you plant them outside, you’ll need to put them through what’s called a hardening-off period.
All you do for this is start putting the seedlings outside for increasing amounts of time over the course of 10 days until they are outside for 24 hours.
This way, the seedlings won’t get shocked, stunted, or die when you put them outside.
I start by putting mine outside for 2 hours, then 4 hours, then 6 hours until they have worked up to being outside for a full 24 hours.
Then they are ready to be planted outside.
When you transplant the tomato seedlings into the ground, you’ll add about a tablespoon of organic granular fertilizer into the planting hole for each plant. You’ll mix that with the garden soil already in the hole, then backfill the garden soil around the plant.
Make sure to plant the seedling as deep as possible, because every where that tomato stem touches soil, it will grow roots. This yields a much more vigorous plant than if you planted shallow.
Every 6 week or so, you’ll side dress the tomato plants by sprinkling the same fertilizer on the ground around the plants and working into the top couple of inches of soil. Be careful to not let the fertilizer touch the leaves or stem of the plant.
Prune your Tomato Plants
After your tomato seedlings have been growing for a few weeks, you’ll need to prune them.
Pruning increases airflow around the plants and decreases the chances of disease. It also makes it easier to see and pick your fruit.
Cut or break off any side stems within a foot from the ground, and cut off any suckers. These suckers can make whole other tomato plant if you put them in water until they grow roots, so keep that in mind.
Harvest
Once you have tomatoes on your plants, you aren’t too far away from being able to taste the fruits of your labor. In about 4-6 weeks, your tomatoes will be ripe and you’re to harvest. You’ll be able to harvest pounds and pounds of tomatoes until your first frost kills your plants.
Tomatoes are one of my favorite plants to grow in the garden and growing tomatoes from seed is such a smart idea.
Now that you have all the information you need to successfully grow tomatoes from seed, check out my next post on the 25 tomato varieties I grew last year so you can see which varieties you want to grow this year!
Conclusion
Tomatoes are one of my favorite plants to grow in the garden and growing tomatoes from seed is such a smart idea.
Now that you have all the information you need to successfully grow tomatoes from seed, check out my next post on the 25 tomato varieties I grew last year so you can see which varieties you want to grow this year!
