Growing Tomatoes From Seeds: A Step-by-Step Guide

If you’ve been dreaming about home-grown veggies but aren’t sure you have a green thumb, fear not. Even though there are certain herbs or veggies (we’re looking at you, lavender) that are a bit more challenging to grow and maintain, there are plenty of others that are almost foolproof. And luckily, the juicy and delicious tomato is one of them.

Growing tomatoes from seeds is easy, affordable, fun, and extremely rewarding. Once your own tomato plant starts to produce, you’ll have a great supply to add to your dishes.

It’s no surprise that tomatoes are one of the best plants to kickstart your home garden or veggie patch. When you pick the right variety, you can even grow them indoors and have an endless supply of fresh tomatoes all year round!

In this article, you’ll find a step-by-step guide for growing tomatoes, the different varieties to choose from, and how to plant tomato seeds so they grow strong and healthy.

The Advantages of Growing Tomatoes From Seeds

One of the main advantages of planting tomatoes from seeds is the cost. A single tomato seed packet is filled with dozens of little seeds and costs a lot less than one tomato seedling from your local plant nursery.

Plus, if you plan to grow organic tomatoes, seed starting makes it much easier to control the elements involved in the plant growth. You can select high-quality organic potting soil or seed starting mix as well as organic tomato seeds, which make all the difference.

But if you ask any dedicated gardener to name the best thing about growing tomatoes from seeds, they’ll have one word for you: variety.

Even though there are more than 10,000 different tomato species in the world, only a few dozen can be found as tomato seedlings in your garden center. However, when you opt for tomato seeds, a whole world filled with infinite possibilities opens up.

Cherry, beefsteak, heirloom, Brandywine, green, yellow, orange, black, and indigo are just a few different tomato varieties. They come in all shapes, sizes, and flavors. The only downside is trying to choose just one! 

Fortunately, it’s super easy to grow tomatoes at home, so you can pick all the different varieties your gardener’s heart desires.

Different Varieties of Tomatoes

Different tomato varieties

When picking the right tomato variety for you, there are a couple of things to consider.

First, how much space do you have to grow tomatoes? 

If you’re starting to worry because your answer is “not a lot” or “just a windowsill,” don’t panic. You can definitely grow tomatoes in small spaces. You just have to select a small-size variety. Some of the best tomatoes to grow indoors are sugar plum, orange Bourgoin, and cherry tomatoes.

Suppose you have more space — like a balcony or a terrace — for a small garden bed or outdoor planter. In that case, you can opt for tomatoes that grow bigger, like beefsteak, Roma, San Marzano, and Giulietta. 

After assessing your space situation, ask yourself how you would like to use your tomatoes.

Bigger tomatoes – often called slicers – can be eaten fresh but truly shine when used to make sauces (hello, pizza and pasta), ketchup, or other condiments.

On the other hand, small-sized tomatoes are fantastic additions to salads, bruschettas, and other dishes that require freshly-picked tomatoes.

No matter which way you go, going organic is always best for quality, flavor, and your health.

Another variety to check out is heirloom tomatoes. These tomatoes are grown from heirloom seeds, which are collected and passed down from season to season. This means they have not been crossbred with other varieties for 40 or more years.

Heirloom tomatoes are famous for their incredibly rich flavors, so if you can, opt for organic heirloom tomatoes to get the best of both worlds.

Step-by-Step Guide To Growing Tomatoes From Seeds

Growing tomatoes from seeds: Seedling tomato plants

Now that you’ve learned a bit about tomato varieties and why growing from seeds is best, it’s time to find out how to actually do it. Use this detailed guide to start growing tomatoes and pick up top tips and tricks to make sure your journey goes smoothly.

Item Checklist

Before you start sprinkling tomato seeds everywhere, there are a few things you need.

Your seed starting kit should include:

  • Organic tomato seeds (duh!)
  • Organic potting soil or seed starting mix: Avoid using garden soil when seed starting as it may contain harmful pathogens or lack essential plant nutrients. 
  • Growing trays or small containers: Biodegradable trays are best because you won’t need to pull your seedlings out for transplanting; you simply place the whole thing into the soil. As an alternative, you can use an egg carton or paper cups.
  • Spray bottle: A glass or metal spray bottle is more sustainable, but if you don’t have one on hand, you can repurpose an empty household bottle. Just make sure to pick one that never contained harsh chemicals, as the residue can damage your delicate baby plants.
  • Plant markers: Popsicle sticks make great plant markers. These markers are like name tags for your plants, which comes in handy when you’re planting different varieties. But if you’re only planting one type of seed, they’re not necessary.
  • Optional utensils: Grow lights and heat mats may or may not be optional depending on your setup. (More on this later.)

When To Start

The best growing season for tomatoes is summer, which is why most seed packets recommend starting your seeds 4-6 weeks before the last frost date. Doing so allows your plant to go through the whole germination and growth process and be ready to bear fruit when warm weather arrives.

If you have no idea when that is, use this Back to the Roots calendar to find out. Simply enter your zip code to receive a customized calendar with all the info you need to grow your plants.

If you’re planning to keep your tomato plants indoors, this is not an issue, so you can start any time.

How To Start

Gardening tools

Even if you’re planning a lush outdoor garden, the best way to start seeds is indoors. By doing so, you’ll give them the best conditions possible to grow healthy and vibrant. Here’s what to do:

  1. Place your growing tray or container of choice on a flat surface and add your potting mix. Do not fill it to the brim, leaving half an inch between the soil and the container’s top.
  2. Place 2-3 seeds per container to make up for any that may not germinate. Space them out with equal distance between each other.
  3. Sprinkle a pinch of extra potting soil on top of the seeds.
  4. Gently pat the surface to make it smooth.
  5. Spray your seeds using your spray bottle until the soil is moist but not soaked. About 4-5 squirts should do it. Once your seeds turn into plants, you can start using a small watering can.
  6. Grab your popsicle sticks and write the names of your tomato varieties and the date you sowed them. Stick them into the growing tray. Tip: If you’re using paper cups or egg cartons, you can simply write the name and date on the side. 


Now it’s time to determine where is the best spot to place your growing trays or containers. Tomatoes are summer fruits, which means they love warmth. A sunny window or windowsill are perfect settings for your baby tomatoes.

Keep in mind that during the germination process, tomatoes love warm temperatures and humidity. If you’re starting your seeds in the middle of summer, make sure you check them regularly throughout the day to keep the soil moist.

On the other hand, if you’re sowing your seeds in winter or in a cold, rainy location, you’ll need grow lights and a heat mat. 

Grow lights have an extra advantage. Since they’re placed a couple of inches above the seedlings, plants grow bushier and stockier than those that grow next to a window. In fact, plants that grow on windowsills can sometimes become “leggy.”

Legginess is when a plant grows long and thin, which makes it easier to break when you transplant it. This is definitely something you want to avoid.

Grow lights also encourage the plants to grow straight up towards the light instead of leaning, which usually happens to plants that grow with natural sunlight. 

If you have plenty of natural sun and light and don’t want to invest in a grow light, there’s a couple of tricks you can do to avoid “leggy” plants:

  1. Rotate your plants regularly, so they don’t lean towards a particular side.
  2. When your seeds germinate, and the first true leaves pop out, gently brush your hands over their leaves a few times per day. This action simulates wind and helps to strengthen the plant’s stems.

Heat mats are also useful if the room temperature of your young plant’s location is too cold. Be aware that the ideal temperature for germination is between 65°-85°F, so if you cannot provide your plants with these conditions, a heat mat is a must.

Successful germination occurs within a week or two after you’ve sowed your seeds.

Now, if you don’t have an outdoor space and you’re planning to keep your cherry tomatoes indoors, you’re settled. All you have to do is choose the pot where your plant will live permanently and move it there. 

If you’ve used a biodegradable growing tray, grab a pair of scissors and separate the cells. Place each section directly in the pot, allowing enough space for the plants to grow. Add enough soil to cover the biodegradable tray or container and water it. Voila!

If you’re going to grow your tomatoes outdoors, we’re not done yet. Keep reading.

Harden Off

Once your baby tomato plants have at least three or four sets of true leaves, they’re ready to be hardened off.

Hardening off is the transition period to adjust your plants from their sheltered indoor life to their new location outdoors. When you complete this period, you’ll have more robust and resilient plants that can withstand temperature changes, windy conditions, and less frequent watering.

Here’s how you do it:

  • Slowly introduce your plants to the outdoors for a few hours during the day. Gradually increase the amount of time they spend outside.
  • Give them 7-14 days to adapt.
  • Start in a sheltered and shaded location.
  • Give them less water, but don’t let them dry out or wilt.
  • Start the harden off process when the outdoor temperature during the day is above 50°F.

Transplant Seedlings Outdoors

Growing tomatoes from seeds: Plant in soil

When you’ve completed the hardening off stage, it’s time to move your beloved tomato plants to their permanent outdoor spot. As mentioned, the best time to do this is two weeks after the last frost date.

  1. When you’re ready to transplant, water your plants.
  2. Place your biodegradable container into the ground or larger container and cover with soil until it reaches the first tomato leaves. Make sure you plant them in a location under the full sun.
  3. If the variety you chose requires a tomato cage or ladder staking, this is the time to put it in place. This information is on your seed packet.

If you’re using outdoor planters or pots, here are a few tips on how to pick them:

  • Avoid plastic pots: Apart from the whole sustainability issue, plastic pots don’t allow for much air circulation and may encourage moldy roots. Terra cotta pots are slightly more expensive but they’re eco-friendly and support your plant’s growth.
  • Check for drainage holes: Drainage holes are vital to ensure proper drainage and avoid water logging situations. 

Growing Tomatoes From Seeds Is Easy, Affordable, and Lots of Fun!

Now that you’ve learned all about growing tomatoes, it’s time to roll up your sleeves and get started. You have all the information to sow, germinate, and support your baby plants so that they start producing the best tomatoes you’ll ever taste.

Don’t hesitate to refer to this guide once you start planting. But don’t stress too much. Growing your own food should be a relaxing and pleasant activity, so just go with your instinct and have a good time.

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