How to Grow Tomatoes From Seed in 7 Simple Steps

Growing tomatoes is a must in my garden each year. I can somehow never seem to grow enough tomatoes – beefsteak, saucing, cherry, heirlooms – I want them all! Romas are my tried and true variety for making pasta sauce (I make and freeze enough in the summer to last a good chunk of the winter months), but I’ve also had great success with San Marzanos.

I always have at least 1-2 sprawling cherry tomato plants because I love that sweet, bursting bite in salads, on toast, and in eggs. And every year, even though I don’t think I have the room, I always find an extra pot or two for heirloom varieties. The colors, shapes, and flavors of those just can’t be beat. I love eating thick slices with a little salt and pepper and an accompaniment of fresh mozzarella.

The point is that tomatoes are iconic. And a whole new world will open up to you once you decide to grow tomatoes from seed. No longer are you at the whim of your local garden center. Instead, you can dream of exactly the type of tomato you want to eat, find seeds, and grow!

Picking The Right Tomato Type

Choosing the right tomato variety is all about identifying how you like to eat them. You can grow beefsteak varieties for slicing and sandwiches, saucing varieties like Romas and San Marzanos, or sweet cherry tomatoes that you pop off the vine right into your mouth! And with the prevalence of online seed retailers, the sky really is the limit.

Seed catalogs really opened up the world of seed starting. They contain a huge selection of tomato varieties including cherry, grape, plum, cocktail, beefsteak, paste, and heirlooms. You can find indeterminate or determinate varieties of each of those, and opt for fruits that range in colors from red, green, yellow, orange, purple, to striped!

The bottom line is that you should take a moment at the beginning to decide what you really want to grow. As I previously mentioned, my garden focuses on Romas (determinate), cherries (indeterminate), and a selection of heirlooms.

Burpee, Baker, and TomatoFest are great places to start looking at seeds, but there are a lot of options out there. Be sure to read reviews, and see how other gardeners have fared with the varieties you’re interested in.

What You’ll Need: Equipment List

Growing tomatoes from seed is an incredibly fun and fairly easy process. It does require some equipment though. Let’s take a look at everything you need – from the must haves to the nice-to-haves – to grow your tomatoes from seed this year.

Growing Tomatoes From Seed

Now that we know what we need to get started, let’s dive right in! This section is set up by steps so you can logically see everything you need to do to successfully start tomato seeds this season.

We’ll talk about choosing the right seeds, preparing your seed starter system, planting seeds, caring for growing seedlings, hardening off your young plants, and finally planting them outside.

Step 1 – Choose Your Seeds

We touched on this earlier, but choosing the right seeds is a critical step that you don’t want to rush through. I get a number of seed catalogs each spring and I always feel like a kid in a candy store when they arrive. You’re presented with pages and pages of the most beautiful produce photos and you want to plant them all!

The first choice you have is the general type of tomato you want to eat this season. If this is your first year growing tomatoes, I recommend starting with a single variety (or maybe two if you just can’t help yourself). Having only a single kind of tomato plant will enable you to simplify the growing process and keep things as uncomplicated as possible.

Once you’ve decided what variety you want and have found the seed retailer of your preference, it’s time to choose the actual seeds! In your first season, I highly recommend going with a variety that is well reviewed.

Gardeners are really great about sharing their wins and their frustrations. If you see glowing reviews for a certain tomato plant, give it a try! Conversely, if there are a lot of reviews talking about poor germination rates, look elsewhere.

Some Top Choices

If you’re feeling a little overwhelmed by the sheer amount of tomato options, take a look at some of my favorites. I have grown a lot of varieties over the years, but these are all tried and true producers that provide incredibly flavorful (and pretty!) fruits.

Rosella Cherry Tomato

I have tried a number of cherry tomato plants over the years and this one is definitely at the top of my favorites list. The plant produces massive trusses of pink to purple cherry tomatoes.

They’re pretty tiny (which is what I like!) – only ½” across – contain very few seeds, and are perfect for fresh eating. Interestingly, because they are so dense, they actually do really well in sauces too. Sometimes I have way too many cherries at one time, so I’ll throw a bunch in a batch of pasta sauce!

Roma Tomato

This is my standby tomato for sauce-making. There are a number of kinds of Romas you can find, but I always stick with the heirloom variety. Since I use these for saucing, I prefer a determinate plant that is going to set the majority of its fruit at once.

San Marzano Tomato

I often compliment my Romas with San Marzanos. They’re not quite as easy to grow, but the flavor of the tomatoes just can’t be beat. If you’ve bought canned San Marzanos at the store, you know what I’m talking about! If I run out of my own sauce during the winter, I always turn to the canned variety of this tomato to make marinara or chili.

Cherokee Purple Beefsteak

This has to be the coolest heirloom beefsteak I’ve grown. I tend to get a lot of cool tomatoes from our CSA, so I typically limit my own planting to 1-2 heirloom varieties.

This one is almost always on my list! An old Cherokee heirloom from before 1890, this tomato has a deep, dusky purple-pink color, has an incredibly sweet flavor, and produces very large fruit. It definitely seems to be a popular choice according to many online retailers!

Step 2 – Seed Starting Preparation

Before you can plant your seeds, you have to choose what type of seed starter system you’re going to use. And I do mean system… Seed starting is incredibly rewarding, but it does require some ‘stuff’ to make it work. Here are some questions you may want to ask yourself prior to getting started:

Choosing how many plants you want to start will be your main consideration for choosing a way forward. Options range from a minimal DIY approach, seasonal indoor systems that you put away after planting, and permanent indoor solutions that are more like furniture.

If you’re planning to start only a few tomatoes this year, you’re probably better off with a DIY approach. But if your goal is to start a large number of tomatoes – or even an entire vegetable garden – from seed, you may need a more robust solution.

Let’s break it down into the done-for-you option that will require some upfront investment, followed by the DIY solution you can do with items already found in your home.

Both solutions will allow you to start tomato seeds this year, so it’s 100% about personal preference. The bottom line is that starting your plants from seed is really fun, so choose the option that gets you excited to plant!

Done-For-You Solution

When I decided to start my own seeds, I knew I wanted an easy system that I could set up once and then roll with it again year after year. My goal was to grow enough vegetables in my home garden to replace what I purchased at the grocery store.

This required a fairly robust system that gave me enough room under my grow lights to accommodate both young seedlings and recently transplanted starts. I opted for the system I’ll outline here.

The DIY Solution

This solution will be perfect if you want to keep seed starting super simple and save money while doing it. If you search for DIY seed starting solutions, you’ll find some pretty creative options, like using egg cartons for seed starting!

People are really great about finding ways to reuse common household items or recycle things for garden use that would have normally been thrown away.

Step 3 – Planting Seeds

Now that we’ve decided what kinds of tomatoes to plant, bought seeds, and set up our seed starting system, it’s finally time to plant our seeds! This is the part we’ve all been waiting for!

Seed starting mixes absorb a lot of water. Most bags will tell you to pour the bag into a container and moisten the entire thing prior to filling your seed trays. If you’re planting a lot of seeds at once, this is a very helpful step. If you’re only planting a few tomato seeds, just pour out as much as you think you need and wet it in a smaller container.

Fill the pre-moistened seed starting mix into each seed cell leaving roughly ½” of space between the top of the soil and the container. Compress it gently with your fingers and add a little more if needed.

Place 2-3 tomato seeds on the top of the moist soil and sprinkle a light layer of seed starting mix over them. Tomato seeds are pretty small and if you plant them too deeply, you’ll never see them again. Your goal is to sow them about ¼” deep. Sprinkling a light layer directly over the seeds gets you right where you want to be.

Lightly mist the top of the soil with a spray bottle filled with clean water. You don’t want to pour water over the top of newly placed seeds since it can wash them away or force them too far under the soil.

Place your seed markers into each cell so you know what type of tomato (or other vegetables or herbs) is in each.

Step 4 – Daily Care of Your Seedlings

Tomato seedlings need care and attention every day. You won’t need to spend a lot of time checking in, but it’s important to have eyes on them often in the beginning.

Watering

Seedlings need consistently moist soil. I have found that self-watering seed trays make this job incredibly easy. All you need to do is keep the reservoir filled and the job is done!

If you are using a more traditional seed tray, you’ll need to check the moistness of your soil each day. Things tend to dry out more quickly under grow lights, so this is really important.

Water the soil once or twice a day with a spray bottle. When your starts are more established, you can move to a teapot or watering can with a small hole.

Light

If you’re using grow lights, the only thing you have to pay attention to is their height. As your seedlings grow, you’ll want to raise the grow lights to keep them 2-3” above the plants. If the lights are too close, the young leaves can become burnt. However, if you keep them too high, your seedlings will become leggy and fall over.

If you’re using natural light, be sure to rotate your seed tray every day or so to prevent all your seedlings from heavily leaning in one direction. Plants always lean toward the light, so you can prevent a weird growth pattern by simply shifting the tray around.

Air Circulation

Air circulation is really important for seedlings. It helps them develop strong stems and it also helps ward off certain fungal diseases. A small rotating fan can be a great benefit here.

Make sure it’s far enough away from your seedlings that they don’t experience too much wind. But close enough that you can see them gently moving. Start conservatively at first, but as your tomatoes grow, you can increase exposure to the fan.

Step 5 – Germination, Thinning and Transplanting

I have always found a lot of joy and childish amazement watching my seedlings grow. From the first tiny green sprout that makes its way out of the soil, to the development of a tomato’s first true leaves, the entire process fascinates me. We’re witness to an entire lifecycle of a living thing and that is a special circumstance indeed.

Germination

Germination is the sprouting of a seed after a period of dormancy, precipitated by the absorption of water, the passage of time, warmth, oxygen, and light exposure. When you see it written out like that, the germination of a tomato seed seems pretty special. And I can assure you that you will be delighted when you first see that green sprout break free of the soil!

After you’ve planted your final tomato seeds, cover the trays with a plastic top (or plastic wrap) to create a greenhouse-like environment. I like to use a heating mat at this stage to help with germination, but as we mentioned earlier, this is an optional step.

If you do use a heating mat, place it directly under your seed tray. This will allow the water and the soil to maintain the ideal temperature for germination and successful seedling growth. Remember, we are shooting for a soil temperature of 68-85 degrees.

Light isn’t necessary at this stage, but it will be once your first seedlings emerge. Tomatoes will usually germinate within 5-10 days of planting if conditions are optimal.

Once the first seedling emerges in each tray, remove the plastic covering and turn on your grow lights (or place in your southern window location). Place your grow lights 2-3 inches above your starts so they don’t become leggy. If you’re using a window, you’ll note that the seedlings lean toward the light. You’ll need to rotate the tray every couple of days to correct for this.

Thinning

Thinning seedlings is a bit of an emotional exercise, but it’s really important to the overall health and continued growth of your tomatoes. Remember when we planted 2-3 seeds in each seed cell?

If more than one of those seeds germinated, it’s time to choose the healthiest one and cull the others.  It sounds brutal, but if you don’t do it, there won’t be enough room for strong root growth and you’ll end up with a runty tomato seedlings that will never produce fruit.

You can start to thin your tomato seedlings once they have 2 sets of leaves. Choose the best looking seedling, and clip the others off right at the soil line with a sharp pair of scissors. Do not try to pull seedlings from the soil since that can disrupt the root system of the plant you will be keeping.

Transplanting

Once your tomato seedling has 2-3 sets of true leaves (these are the actual leaves of the plant, not the cotyledon leaves the seedling first produces) you can think about transplanting them to a 3”-4” nursery pot. The first true leaf should arrive about 10-14 days after germination. Subsequent leaves follow shortly thereafter.

Repotting is important to encourage continued growth of your tomato seedlings. If you leave them in small seed cells, the plant would struggle to survive outdoor planting; the root system just wouldn’t be developed enough.

I like to repot my tomato starts in flexible 3”-4” nursery pots. These are made from flexible plastic that allows for easy release of the tomato plant when you’re ready to plant outside. It’s also just the right size for your young seedling to grow without feeling overwhelmed by too much space. If you want to grow specifically in pots long term, tomatoes need bigger pots as the season heats up.

Transplanting From Plastic Seed Tray

If you have chosen plastic seed trays or another non-biodegradable DIY solution, you need to remove the seedlings to place them in their new home. I use a spoon for this task, but you can also purchase a tool called a widger that is designed for transplanting seedlings.

Either way, gently push the spoon down one side of the cell all the way to the bottom. Pull up the spoon that is now cupping the tomato root system and gently place into the new pot. Hold the seedling by the soil and not the stem; otherwise you risk breaking the young stem from its roots.

Transplanting From Biodegradable Seed Tray

If you opted for a biodegradable seed tray like small CowPots or peat pots, your job is a little easier. Cut the cells apart from one another and then cut off the top part of the pot above the soil line. You will then bury the entire cell into your 3”-4” nursery pot.

Bury the Stem!

Tomatoes are unique because the plant can grow roots from any part of its stem that is buried underground. This is really helpful knowledge with seed starting, because invariably, some of your seedlings will seem leggy. When you transplant, you get to help the plant fix this.

First, remove any lower leaves on the stem, but ensure you leave at least 2 sets of leaves at the top. Fill your nursery pots with enough moist soil (I also use seed starting mix for this step) that the seedling will still have 2 inches of stem above the soil line when filled.

Place the seedling in the pot and fill in with more soil. Gently press down the newly added soil to ensure the seedling is stable and then water gently but thoroughly.

After you’ve finished transplanting, place your seedlings back under the grow lights (or by your southern exposure window) and continue your daily care habits.

Step 6 – Hardening Off

So far, your tomato seedlings have lived in a very sheltered environment. Perfect temperatures, ideal light exposure, gentle breezes… This is a far cry from what your plants will experience in the great outdoors. This is where hardening off comes into play.

Hardening off is a simple, but necessary process that allows your tomato seedlings to acclimatize to heat, wind, and sun. During this period, your young tomatoes will ‘grow up’ a bit. Their stems will thicken, leaves will reach out strongly, and roots grow more quickly. All of this helps the plant deal with temperature changes, strong gusts of wind, and direct sun without any problems.

The hardening off process should take a week or two. The longer you give your tomatoes to adjust, the healthier and stronger they’ll be when you finally plant outside.

Start by setting your tomato seedlings in a protected shady area for about an hour. The next day, put them in the same location, but for 2 hours. The day after that, you can let them experience a little bit of gentle morning sun. Gradually increase sun exposure and time outside each day. The idea is to introduce new things in manageable chunks that allow the plant to adjust in small ways each day.

A note on wind. It is important to protect your young tomatoes from wind in the first week of hardening off. After that, allow them to experience normal gentle wind currents, but move them if you’re experiencing extreme wind gusts.

Once you have hardened off your plants for 1-2 weeks, you can plant them in their final location and look forward to an abundance of fruit!

Step 7 – Planting Outside

We’re in the endgame now! You’ve done all the hard work to grow young tomato plants from seed and now you’re ready to put them outside in your garden. So when is the right time to do this?

The short answer is that you can plant your tomatoes outside once they have been hardened off and you are two weeks past the last frost date of your area.

With that said, every area has its quirks. Where I live in northern VA, we experience volatile springs. We may have a week or two of temperatures in the 70s or low 80s, but then have another 3 weeks of temperatures in the 50s. Because of this, gardeners in my area wait until Mother’s Day to plant tomatoes and other warm weather crops even though we’re technically far past our frost date.

If you’re unsure when to plant in your area, join a local gardening group and ask! Local gardeners are more than happy to help, especially when it may save you from a lot of heartache!

Just remember that tomatoes like to be outside once nighttime temperatures are above 60 degrees. If you plant them too early, they will not grow well.

Let’s Plant

It’s time to put your tomato seedlings in their final home! Start by digging a hole about twice as large as the pot your tomatoes are currently in. If you haven’t amended your soil at all, this is the time to do it. Add tomato fertilizer (designed for early growth) and some good organic compost to the soil.

If you used flexible nursery pots for the previous stage, gently squeeze the sides to loosen the soil. Tilt the pot sideways, gently grip the base of the stem, and slide it out. You shouldn’t feel any resistance here; the plant should slide out quite easily from the pot. If you do, try watering the soil to moisten it more and try again.

If you used biodegradable pots, you’ll plant the entire thing into the ground. The only thing you’ll need to do is trim off any part of the pot above the soil line so it doesn’t stick out (just like you did with the first transplanting).

This final transplant is another opportunity to help the tomato grow strong roots. Remember, tomatoes will grow roots from any portion of the stem that is buried underground. I always trim off at least one set of leaves to allow me to bury the plant a little deeper in the ground. Feel free to trim off 1-3 sets of leaves as long as you leave 2-3 sets of leaves above ground.

Once the plant is as deep as you want it, cover the root ball with soil and gently press down with your fingers. Add mulch around the base of the plant to help it retain moisture and the water deeply. This is the time to stake your plants as well. Place your tomato cage carefully around the plant and press the tynes into the soil. This will allow you to stake your tomatoes without affecting the root system.

It’s a good rule of thumb to keep your newly transplanted tomatoes well watered for the first week after planting. This will help the plant settle in and encourage root expansion into the new soil.

Frequently Asked Questions