Growing Tomato Plants From Seed: The Ultimate Guide

(As an Amazon Associate, I earn from qualifying purchases. This website also participates in other affiliate programs and is compensated for referring traffic and business to these companies.)

Tomatoes are easy to grow. This vegetable may look tempting in your local store, but you don’t know what kind of chemicals are used in its cultivation. That’s why it’s better to grow it yourself, preferably from the very beginning, from seed.

Here you will learn about growing tomato plants from seed, step by step. We will talk about some tips to keep in mind when sowing, transplanting seedlings into your garden, and caring for them.

Advantages of Planting From Seed

Lot of red beefsteak tomatoesWhy is it better to plant tomatoes from seeds compared to purchased seedlings?

When we buy seeds, we can choose between different types of tomatoes.

There are long season, short season, cherry, grape, heirloom, beefsteak, red, green, yellow, orange, hybrid, and many more. All these species also have Cordon (indeterminate) and Bush (determinate) variants.

On the other hand, we have a limited selection of tomato varieties when we buy seedlings.

Two ways of growing tomatoes:

  • Cordon (indeterminate): the plant grows tall. The leaves are not compacted and look like vines.
  • Bush (determinate): the plant is shorter and wider, and the leaves are compact on the stem. It is suitable for small gardens. 

So, first decide which type of tomato you want to grow.

Sowing – Growing Tomato Plants From Seed

Buy a packet of 20 seeds (price of one seedling). It is important that they are fresh seeds, because they germinate better than seeds that are several years old.

Required Material 

  • Tomato seeds
  • Starting potting mix
  • Small containers with drainage holes
  • Something to mark your pot
  • Spray bottle
  • Water

When to Sow the Tomato Seeds?

Always start sowing indoors, preferably 2 or 3 weeks after the last frost.

You can also start it 2 weeks before the last frost. However, keep in mind that tomato is a plant that requires warm soil. The soil must never be cold.

Starting Trays Preparation

Starting trays for growing tomatoes from seed are small containers. They can be made of plastic, cardboard or biodegradable material.

Specialized stores sell the biodegradable trays. You can also buy them online on Urban Leaf. When it’s time to transplant the seedlings into the garden, just dig a hole and insert these containers with seedlings. That is it. The containers just decompose over time.

You can also use toilet paper rolls, egg cartons or paper cups. Make holes in the paper cups for the passage of water (drainage).

In fact, all these containers must provide good drainage. Water should pass through those holes well so that the roots are not too wet. Otherwise, rotting and decay of the plant itself may occur.

Starting Potting Mix Preparation 

You also need a potting medium in which you will sow the tomato seeds. It can be potting soil or soilless potting mix. Both should be sterile, namely without pathogenic microorganisms. Check the packaging.

 For this reason, it is not recommended to use ordinary soil from the garden because it contains pathogenic microorganisms. They can damage the seed, later the seedling and affect the tomato fruit itself.

 Above all I recommend soilless potting mix that contains peat moss and vermiculite. It usually contains fertilizer, which works until you transplant the seedling into the garden. Later, you should add liquid fertilizer periodically.

The starting potting mix should be light, well draining, with a lot of nutrients.

The Sowing Process Itself

First, moisten the starting potting mixture and then fill the containers with it. Lightly press the potting medium, in order to expel air pockets.

 Place 3 or 4 seeds on the surface of the potting medium and add some potting mix or vermiculite on the top. Vermiculite is a mineral that has the ability to retain moisture, which is important for plant growth.

Why Should You Put More Seeds in the Starting Tray?

 Some seeds cannot germinate. That’s just the way it is. The older the seed, the lower the germinate rate. There are also seeds of some types of tomatoes that naturally have a low germinate rate. Sometimes the manufacturer notes this on the bag, so check.

Placing more seeds in the starting container increases the chances of successful germination.

RELATED ARTICLE: Read “10 Best Vegetables to Grow in the Garden”.


When you sow the seeds, you need to have markers. Write on them what type of tomato it is, then stick markers in the potting medium.

 Paper cups are convenient because we can write on them with a felt-tip pen.

When the tomatoes grow, these markings will help you know exactly which type of tomato it is, in case you have bought several different types.

Caring for the Seedlings

Containers with seedlings should be in a place that is warm, sunny, and with high humidity.

 You can achieve these conditions by covering the starting trays with plastic wrap. It imitates greenhouse conditions. As soon as the seeds start to germinate, remove the cover.

Check the seedlings daily, with proper care. Don’t worry, it doesn’t take much time!


You can place the container in a sunny south-facing window.

 Instead of natural light, it’s OK to use a LED grow light (like this one on Urban Leaf)


Spray bottles are best for watering the plants. This can prevent overwatering. Too much watering the plant can lead to rotting and later to the complete decay of the plant itself.

Correct watering should be carried out 1 to 2 times a day.


Germination begins after a week or two. When the first real leaves come out, transfer those small seedlings to slightly larger containers.

Hardening Off

After transplanting the plant into larger containers, leave it there for at least 2 weeks. Start with the hardening off the plants. In other words, prepare the plant for outdoor life. This transition period should last one to two weeks.

 When the days are warm, take them outside for a little bit every day, first for an hour, and then for longer. Gradually increase the time of exposure to the sun and the wind.

 This way, the seedlings get stronger and prepare for life outside.


When the seedlings grow 2 inches, start thinning them. That way you improve their growth.

Transplanting Seedlings Outdoors

The next step is transplanting the seedlings outdoors, in the garden, or in the greenhouse.

You should do that when there is no frost threat and when the soil is warm.

With a special soil thermometer, you can check the soil temperature. It should be 60 F (16 C) and higher. The soil must not be cold, because tomatoes love the heat.

Tip: Plant seedlings deep in the soil, ⅔ of the plant under the soil.


When the seedlings are transplanted, start with occasional fertilizing with liquid fertilizer. In this way, the growth of the plant is accelerated and improved.

Fertilization should begin when the seedlings are at least 4 weeks old.


Lay a thick layer of mulch over the soil. This will improve plant growth.

When It’s Time to Harvest?

Smaller tomatoes, red and green on the stemsIt takes about two months from transplanting the seedlings outside to harvesting.

Then you can enjoy the fruits of your labor, delicious organic tomatoes.

Final Note

Here you learned how to sow tomato seeds, transplant the seedlings into the garden and care for the plant until harvest.

This hopefully readable and easy to understand article has shown you all about growing tomato plants from seed. Now go ahead, take an action and make the healthiest tomatoes for yourself and your family.

If you have any suggestions or question about Growing tomato plants feel free to join the discussion. Please leave a comment below.

Share with Your Friends

Leave a Comment