Starting Tomato Plants From Seed

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If you are looking to starting tomato plants from seeds you are in the right place. Get step-by-step help that you can use to start a backyard garden with amazing organic plants you started from seeds.

starting tomato plants from seeds

It’s that time of year up here in Northwestern PA. Even though the snow is still flying outside it’s seed starting time for our summer garden side. Since our growing season is a bit short, starting some of our seeds inside now will ensure our plants are the right size come Memorial Day which is our planting time.

Up north, the end of May is when we are pretty safe to put our young seedlings and plants outside in our gardens.

Since our growing time is shorter than most, it is helpful to get a jump on things. And the best way to do that is to plant seeds inside and let them grow until you are ready to transplant. If you have not yet tried your hand at starting tomato plants from seed it’s so much easier than you think.

Not only that, it’s a great way to start a garden from scratch and really ensure you know the exact source of your food.

Can starting your own seeds save money?

Where I live a flat of tomato plants can cost around $18. Whereas a packet of good seeds cost about $3 and the organic seed mix is usually under $5.

A flat is a container of small pods that are used to house and grow seedlings. A flat will hold about 18 plants.

a flat of young tomato seedlings growing in a flat

Two packets of seeds and a bag of potting soil for starting seeds will allow you to start and grow about 2+ flats of plants if not more.

So you can see right off that growing your own plants is a cost saver of about $28.00. Just another reason why you should give this a try!

Before we dive into starting plants from seed, there are a few things you will need to have first. 

1. First,  you will need to designate a place in your home to grow your young plants or seedlings. A place that is warm (although it’s not a requirement) and one that is out of the way of tiny hands and nosey pets. 

2. Next, you will want a stand of sorts to hold your flats of delicate plants. Yes, you can purchase stands and pretty elaborate growing systems. But I like to do things on the cheaper side and try to reuse what I have on hand before heading out to the store to buy.

For example, an extra metal shelf that you are not using or even a table that you can repurpose will work great to hold your flats up and out of the way while they grow.

Your goal is to find a sturdy platform that is large enough to comfortably hold a few flats of plants.

Tips for Starting Tomato Plants From Seeds

This guide will walk you through all the steps from start to finish on starting tomato plants from seeds. Be sure to research the planting time in your area so you can more easily know when to put your seeds into the ground. Your goal is to have seedlings that are strong enough to handle the outdoors temps.

Step #1  Gather your containers

Before you purchase new containers for your seeds, take a look at what you already have. If you have ever purchased plants then you are probably familiar with the plastic containers they come in. From now on, never EVER throw those out.

Even though they may seem flimsy, they are more durable than you think and are perfect to use when starting your new batch of seedlings.

a plastic seedling container lying on it's side with the words _keep these_ in a red arrow

I believe I am in my 10th year with these same plastic containers and they are still holding strong.

I also have the trays the plants came in which are really convenient when you are moving from inside to outside.


These trays are also great for keeping water from dripping all over your floor when you are watering your flats.

a stack of seed flats and soil on a counter

Step #2  Start with a good soil mix

When starting vegetables and tomato plants from seed, the key is to use good quality starter soil.

I prefer to use an organic seed starting mix, although I have used others with good success. What do I mean by that? Well, invest in a starter you can afford especially if this is your first time.

Each year you can increase the starter quality for your seeds. For our area and the clay soil we have to work with, the better the seed starter the better our seedlings do in the garden.

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I like the quality of this mix and have always had great luck with it. Remember if you want strong and healthy plants then you need to start with good quality soil. This will give your seedlings the environment they need to grow strong and sturdy root systems. Root systems are the key to healthy plants and help your harvest to be a bigger and more abundant one. 

The good news is, it is easy to find a good mix that fits into your budget, and it is sold just about everywhere both online and in stores.

a hand feeling the soil in a pot where pepper plants are growing

Step #3  Clean and sanitize your containers 

If you choose to reuse planters as I mentioned above you will want to wash and sterilize them before using them again. This will remove any old soil along with any leftover pest residue or lingering diseases from previous years. I like to use a bottle brush (bought from the dollar store) and warm soapy water with a bit of bleach added in.

Wash each container, rinse it well, and stack on a large towel to air dry. If it is a sunny day, you can allow your containers to dry in the sunshine. The sun acts as a natural sanitizer and is a great way to dry things up rather quickly. 

cleaning supplies, bleach, gloves, brush and bucket used to disinfect seed planters

When using bleach, make sure to wear gloves so the bleach does not irritate your skin. The ratio I use is about 1 part bleach to 9 parts water. I usually just fill a bucket and pour in a little bleach, eyeballing the measurement.

Your goal with wasging is to remove any disease, if there is any, before planting your seeds giving them the very best environment to grow in early on. 

Step #4  Prepare your soil

One of the best tips I can pass on to start plants from seed is to make sure you presoak your starter mix.

I have tried to plant my seeds without presoaking and they took forever to sprout setting me back a full week on my schedule. The seed mix contains peat moss which will help to hold in moisture giving your seeds the perfect foundation for growth.

But adding water to seed starting mix is tricker than you might think. That’s because the main ingredient in most seed starters is peat moss as I mention above. Peat moss is really loose, lightweight, and rather dusty.

I have found that pouring a supply of seed starter into a large container such as a washtub you can prepare a large amount of soil without too much of a mess.

dish of soil used to start plants from seed for an organic garden

How to Soak Seed Starter Mix

Pour in some soil into your container and add a generous amount of water. I like to use the spray nozzle on the hose at my kitchen sink. This allows me to add water more evenly over a larger area.

Next, take a large wooden spoon and work that water into the mix. Continue doing this until the soil is thoroughly damp yet not soaked.

If you accidentally get the soil too wet you will want to let it sit for a day or two to dry out. Be sure to mix it a few times each day to help it dry more evenly.

Once the soil is to the right consistency (damp but not wet) it is ready for planting your seeds. 

Step #5  Plant your seeds

When planting your seeds please be sure to follow the instructions on your seed packets.  The actual time you plant your seeds will all depend on the zone you are in and when you are able to transplant your seeds outdoors. You can find your zone here.

Usually, you want to start your seeds indoors approximately 6-8 weeks before the last frost of spring in your area. Always make a note of times and plantings in your garden planner. Keeping good notes will save you loads of time every year. It will also keep you on the correct timeline.

tiny tomato seedlings growing in a flat filled with soil

A garden planner is a crucial part of your garden library. This is where you will journal your growing season year after year so you can improve as a gardener year after year.

1. Begin by putting a layer of soil into each container of your seed flat.

2. Using your fingers lightly tamp down the soil without compacting it.

3. Next place 2 seeds per pot to ensure the growth of at least one plant. If both seeds take, you will need to pull one of the seedlings out later so that all the water and nutrients in the soil will be focused on just one plant. This will help the remaining plant to grow a strong root foundation that is important for an outdoor garden. 

4. Once all the seeds are planted cover them with a layer of soil. Again you will want to tamp down the soil lightly over each seed.

5. As the dirt settles you can add in additional soil as needed. For this purpose, I usually keep damp soil ready for the first few weeks so I have a supply that is damp and ready to add in if needed. 

A flat of soil waiting to be planted with seeds

Step #6  Set up an indoor growing system

The great news about setting up a growing system is just about anything you have will work. There are just 2 things to keep in mind while setting up.

  1. Choose a space that is out of the way place so it is not is risk of being knocked over.
  2. Choose a space that is relatively warm.

Shelves work great if you have any available. This includes stationary shelves or a metal shelf unit. You can also use a table or other flat surface.

When I first began growing my own seeds I used an old kitchen table that was in my craft room. I placed my flats under the table so they were out of the way while I was crafting and suspended my lights from lightweight chains attaching them to the sides of the table. 

The lights I use are 4 feet long and I find they are the perfect size for a flat of plants. If the area of the home is warm, normal bulbs will usually give off enough heat allowing your plants to grow well.

flats of plants growing under lights below a table.

If you are growing your plants in a colder area such as a basement, you will need to do a bit more to keep your delicate seedlings warm enough to grow.

You can use inexpensive plastic sheeting to wrap around your growing area. This will help to keep any warmth inside with your plants, turning your growing area into sort of a makeshift greenhouse. 

a woman taping up plastic wrap about shelves to create a green house

Your goal is a constant temperature of 65-75 degrees. You can place a thermometer inside of your setup and monitor the temperature daily. 

Step #7  Water gently and correctly.

In the first few days, you will not need to water much if at all, since you already dampened your soil before planting. When you do begin to water your seeds, I suggest using a disposable water bottle.

I find I can control the amount of water much better with one and there is less risk of drowning the seeds. Remember to water gently giving just enough without saturating them.

Once the young plants have sprouted you can then switch to a spray bottle. This will water your delicate seedlings without crushing them. It is so important not to overwater, especially in the beginning.  If you are not sure, just check the soil with your finger. Gently feel the soil, if it’s wet, don’t water.

a woman putting flats of seeds on a metal shelf that is wrapped in plastic (1)

Depending on the type of seeds you plant you should see something sprout at about 6-8 weeks. If after 10 or 12 weeks you still see nothing breaking through the soil, then I would assume the seed did not take.

Please refer to your seed packet to verify that you have given your seeds enough time to sprout. If your temperatures are not warm enough it may take longer for your plants to break the soil’s surface which is something to keep in mind. 

Step #8  Add more soil.

You may notice after the first few days the seed mix begins to settle a bit and you will need to add more soil. This is normal and will happen a few times in the beginning. This is why it is good have to extra soil that is damp and ready to go.

Add soil as you see it is needed using your finger to lightly tamp thing down into place.

Step #9  Thin your seedlings 

This is always the hardest part for me.

Remember in step 5 I told you to put 2 seeds into each planter? Well if you notice that you have 2 or even 3 sprouts inside of one growing section you will need to remove all but one.

Choose the strongest seedling to keep and gently remove the extras. The best way to do this is to use your finger to gently hold the base of the seedling you are going to keep. You can then slowly and safely remove the other seedlings.

Grab the seedlings you are removing with your free hand and gently pull them out holding the other seedling in place. 

tomato seedlings in a flat

If you had seeds that did not sprout you can transplant an extra seedling in that spot. They may not take as transplanting can be traumatic for a young seedling, but there is a chance that they will.

Step #10  Hardening up your plants

As it gets closer to planting time you will want to begin hardening off your plants.  That means getting them acclimated to the weather so they are better able to withstand the fluctuations that tend to hit in the springtime. This is especially important if you live in a cooler climate as I do.

To harden off your seedlings, take your planters outside on a sunny and preferably windless day and let them soak up the rays of the sunshine. Try to keep it short and sweet in the beginning so you do not damage your plants. As the seedlings strengthen up you can increase the time longer and longer. 

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Step #11. Transplant your seedlings into your garden 

This is the most exciting time for gardeners, getting those new plants into their summer garden. How you space, plant, water, all depend on the vegetable you have. For us, we will be transplanting tomato plants.

Be sure to space your tomato plants approximately 2 feet apart so there is plenty of space for them to grow. Add support now by using sturdy stakes or cages. The reason I like to do this early is so the plants can grow around the cages using them in the most beneficial way.

When setting up your garden, location does matter. Most vegetables including tomatoes love sunshine so choose an area that gets 6-8 hours of sun a day.  

I prefer to use raised garden beds for our vegetable garden. This allows me to grow more in a smaller area giving me the most harvest year after year with less work. Raised beds are also easier to keep weeded, watered, and safe from predators such as rabbits and dear. 

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If you don’t have a garden, don’t worry, you can grow all you need right on your front porch using buckets, pots, and other containers. 

Read:  How to Grow Tomatoes in Pots – A Step by Step Guide.

Starting tomato plants from seeds is not only economical but easy and fun as well. I just marvel each summer as we enjoy those beautiful tomatoes that all started from a tiny little seed.

Try your hand at it this year so you too can enjoy the fruits of your labors come summer.

More Gardening Resources:


  1. Great post! I’m usually starting seeds as well but we’re anticipating a move so I’m not going to be starting any. thank you for sharing your post on Our Simple Homestead Hop, as one of the co-hots I will be featuring your post tomorrow! Look forward to what you’ll be sharing this week!
    -Nancy ( Nancy On The Home Front )

    1. Hi, Nancy,
      I am so happy you enjoyed it and that it will be featured. You just made my day!
      Thanks for stopping by! Good luck with your move. 🙂
      Tracy Lynn


    1. Hello, Vincent.

      Yellow plants could be a few things. Too much water for one. Make sure the soil is moist but not soaked. Another is not enough light. If you have your plants under grow lights, maybe raise them up by stacking a few books underneath.
      Those two things should fix them for you!
      Tracy Lynn

  3. Suggestion: If you have more plants per pot then wanted or needed, don’t pull the extras out. Instead, cut them off with scissors so you don’t disturb the remaining plant.

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