A Guide to Growing Tomatoes from Seeds

One of the most popular members of the vegetable garden, lots of people, myself included, love growing tomatoes. As many gardeners will tell you, once you have tasted a homegrown tomato freshly picked from the garden, store bought types will never taste as good again.

While many people buy young plants or transplants from garden stores you can also grow from seed. This offers you access to a wider range of varieties.

The local garden store or plant nursery may only have a few of the more popular varieties stores while growing tomatoes from seeds enables you to access a wider variety of shape, color, size and flavor. A seed catalog shows you the endless options available from heirloom types to open pollinated or hybrids as well as bush and vining varieties.

Growing tomatoes from seeds is also cheaper and surprisingly easy. All you need is a little patience and some space. This guide to growing tomatoes from seed is designed to take you through the entire process, from seed selection to sowing and planting.

1 Growing tomatoes from seeds
You can grow a great tasting tomato from seed.

Different Types of Seeds

Look through a seed catalog and you see terms like “heirloom”, “hybrid”, “heritage”, “F1” and “open pollinated” used to describe the different varieties of tomato seeds. These terms may sound daunting but once you understand them they can help you select the right type of tomato plant for your garden.

Heirlooms or heritage types are open-pollinated plants that have been grown for generations. These are packed with flavor. Most heirloom varieties have a superior flavor than hybrid varieties. Heirloom fruits also offer a diverse range of shapes, colors and sizes. Popular types include:

  • Brandywine,
  • Pineapple,
  • Cherokee Purple,
  • Big Rainbow.

Open-pollination means that the flowers are pollinated in the open by insects or the wind. The flowers can also be pollinated by hand. If you save the seeds from open-pollinated fruit, the following years plants usually grow true to type. This is true unless cross-pollination occurs. This is most likely to happen if you are growing more than one variety. If you only grow one type, cross pollination is unlikely to happen.

All heirloom varieties are open-pollinated but not all open-pollinated varieties are heirlooms. Common types include:

  • Glacier,
  • Dwarf Sweet Sue,
  • Dwarf Caitydid.

Hybrid plants are cross-pollinated tomatoes. This means that the pollen of 2 types are mixed purposefully by breeders. In seed catalogs they are listed as F1 types. These seeds can’t be saved for sowing the following year because they wont grow true to type.

Hybrid varieties are more disease resistant than heirloom varieties. They also offer higher yields, display a more vigorous growth habit, ripen uniformly and can, in most cases, be harvested earlier.

How to Choose the Best Tomatoes Seeds for Your Garden

For many people the most difficult part of growing tomatoes from seeds is selecting which variety they want to grow. When making your decision try to keep these 3 factors in mind:

  • Space,
  • Length of Season,
  • What you want to use your tomatoes for.


How much space you have is an important consideration when selecting which variety of tomato you want to grow.

Tomato plants grow as either determinate or indeterminate.

Determinate types are best for small spaces and container gardens. These are compact plants that typically grow to a height of 2 to 3 ft. The fruits mature around the same time. This is often much earlier than the fruit of most indeterminate types. One of the most popular types of determinate tomato is the juicy Roma tomato.

2 Growing different tomato varieties from seeds
Different varieties have different growth habits and requirements.  

Indeterminates, sometimes known as vining varieties, are larger plants. They can easily grow to a height of 6 to 8 ft tall. The plants often continue developing and spreading until the first frosts of fall. Consequently they require a lot of space. They also require support from stakes or tomato cages. This helps to keep the vines spread out and off the ground.

Elevating the vines also frees up soil beneath the plants for you to grow a crop of leafy greens. Vining varieties are best grown in the ground, raised beds or large containers. Many cherry tomato varieties are indeterminate plants. The popular Better Boy is a reliable indeterminate hybrid variety.

If you are growing tomatoes from seeds in a container garden, here is a list of the best container varieties.

Length of Season

Often seed catalogs categorize tomato seeds by how long they take to mature, splitting the plants into 3 categories:

  • Early,
  • Mid-season,
  • Late season.

If you enjoy only a short growing season, cultivate early or mid-season fruit. Gardeners who have more growth time can also cultivate late season varieties.

A reliable early season hybrid, Bush Early Girl matures in around 55 days. The equally reliable Gardener’s Delight takes around 68 days and Sun Gold just 57 days.

Abraham Lincoln, which matures in around 77 days, Beefsteak and Brandywine, both of which mature in around 75 days are all good mid-season varieties.

Late season tomatoes take the longest when growing from seeds. For example Dad’s Mug a large slicing tomato takes up to 85 days to mature.

You may also see days to maturity listed. This explains how long the plants take to grow from seed and produce mature fruit. In coastal or short-season gardens, types that are quick to mature such as Moskovich, which requires 60 days, or Sun Gold are best.

What You Want to Use your Tomatoes For

Different types of tomato plant produce fruit of different sizes and shapes. Larger fruits such as Beefstakes are often best for slicing and putting in sandwiches, while smaller, sweet fruits are best used whole. While some varieties, such as Romas or San Marzanos are great for using in a sauce others, such as Plum tomatoes, are good for canning.

3 Different tomato varieties

Different tomato varieties have different uses.  

Decide what you want to use your tomatoes for before you select your seed varieties.
If you have the space, planting a mixture of types, such as beefy heirlooms for slicing, sweet cherry tomatoes and canning varieties enables you to enjoy the fruit in a range of different ways.

Whenever possible try to use organic non-GMO types of seed. This is particularly important if you want to save the seeds from your tomatoes to sow on next year.

Take the time to research the different varieties on offer and select some that suit your growing conditions as well as your personal tastes.

When to Start Growing Tomatoes from Seeds

Once you have selected your varieties, it is time to start growing tomatoes from seeds. Tomato plants are best started undercover. This enables you to give the seedlings the best possible care before transplanting to their final growing position.

When to Sow

Knowing when to sow is an important part of growing tomatoes from seeds.

It usually takes 6 to 8 weeks for the seeds to germinate and grow sufficiently that they are ready for transplanting into their final growing position.

Do not start growing tomatoes from seeds too early. This can mean that they are allowed to sit in their pots, waiting for outdoor temperatures to warm up, becoming leggy.

Allowing seedlings to sit in pots for too long can also cause the root system to become compacted. This can stunt growth and stress plants.

4 Sowing tomato seeds at right time
Sowing at the right time prevents them becoming leggy and outgrowing the pot.

You can transplant tomato seedlings into their final growing position as soon as the last frost date has  passed and the soil has warmed up sufficiently. To work out when to start sowing and growing tomatoes from seeds, find out your last predicted frost date and count back 6 to 8 weeks. This is the ideal date to start growing tomatoes from seeds.

What You Need to Begin Growing Tomatoes From Seed

Before you begin there are a few things that you will need. The most important of these is viable tomato seeds.

You will also need:

  • Seed starter potting medium,
  • Seed Starting or Cell Trays,
  • Small Pots,
  • Plant mister spray or small watering can.

If you don’t want to invest in seed starting trays you can also use clean yogurt pots, egg cartons or even clean egg shells.

However, if you are serious about growing tomatoes from seeds, Seedling Starter Cell Trays are a great investment. They fit nicely into propagators and under grow lights. They are also reusable meaning that you can use them year after year to start a range of fruits, vegetables and flowers.

5 Growing tomato seeds in cell trays

Sow the tomato seeds in cell trays.

Depending on when and where you are starting your plants you may also want to use a propagator, heat mat or grow lights.

How to Start Growing Tomato Seeds

To start growing tomatoes from seeds fill your seed starter or cell trays with your chosen growing medium such as Jiffy Natural Organic Seed Starter mix.

Seed starter mixes are preferred over ordinary potting soils because they are lightweight and drain well. Made up of a mixture of beneficial materials such as vermiculite or perlite and compost, seed starter mixes also often contain slow-release fertilizer. This helps to stimulate and support seedling growth.

6 Sow tomato seeds on moist soil
Sow on moist soil.

Moisten the potting medium.

Carefully sow your chosen tomato seeds. How many you sow depends on how many plants you want. Work this out and then sow a few extra seeds to guard against seedling failure.

Any seed that you don’t use can be stored in an airtight tin or jar for use the following year. Seeds remain viable for a few years if stored correctly. Remember to label your seeds.

7 Label tomato seeds

Label the different varieties.

If you are sowing in cell trays, sow 2 to 3 seeds per cell. If all 3 germinate, the weaker seedlings can be thinned out later on.

An important point to remember when growing tomatoes from seeds is to not plant the seeds too deeply. If planted too deeply, the seeds struggle to germinate. Aim to sow roughly one-quarter inch deep. Cover the seeds with a light layer of moist, potting medium.

If you are sowing more than one variety of seed, remember to label the trays.

Seeds germinate in temperatures of around 68 to 70 ℉. Placing the pots or tray in an Early Grow Domed Seed Propagator helps to keep an even temperature around the seedlings.

You can also cover the trays with a plastic dome or even place them inside a clear plastic bag. Any of these options helps to trap humidity and maintain temperature and moisture levels.

Placing the trays on a heat mat keeps the seedlings warm and encourages germination. Following germination the heat mat can be turned down or off.

Place the trays in a light position. While the seeds don’t need light to germinate, exposing young tomatoes to natural light encourages seedlings to grow strong and healthy. Ideally the plants require 14 hours of light every day.

8 Tomato seeds germinate

Seedlings germinate in a few weeks in a light position.

Seedlings growing in too little light can become leggy, meaning that they tend to stretch up to the light and fall over, sometimes snapping in the process.

If you don’t have a naturally light position you can use grow lights to supplement natural light levels. If you are using natural light, rotate the tray every few days. This prevents the seedlings from leaning towards the light and becoming lopsided.

If you are using grow lights, regularly raise them so they are always 3 inches above the seedlings. Allowing the seedlings to grow too close to the lights can burn the leaves.

Don’t put the lights too far from the plants, this can cause them to become leggy and fall over.

Keep the soil evenly moist. Overwatering seeds or seedlings is the quickest way to kill your plants. I like to keep a LAWNFUL Electric Spray Bottle close to my seedlings. This allows me to quickly spray the soil as soon as it shows signs of drying out.


Caring for Tomato Seedlings

Following germination, continue to regularly spray or mist the soil. Allowing the soil to dry out can cause seedlings to fail.

Lots of potting mixes contain a slow-release fertilizer that slowly feeds your plants over the course of several weeks. You can supplement this with an organic, water soluble or liquid fertilizer. Products such as Fox Farm Concentrated Liquid Fertilizer should be diluted before use.

9 Care for tomato seeds

Carefully care for the delicate seedlings.  

Dilute your chosen fertilizer, applying no more than half the recommended rate once every 14 days.

Once your tomatoes have germinated, any covers or propagator lids can be removed. This enables air to circulate around the seedlings.

Air circulation is an important element in the cultivation of healthy plants. If you are growing tomatoes from seeds in a room where air is unlikely to circulate, use a small oscillating fan to move air around the room. This helps to toughen the stems and foliage as well as preventing fungal issues from developing.

Following germination, thin out the tomato seedlings. If you have sown 2 to 3 seeds per cell, thin out so that only the healthiest seedling remains. This prevents overcrowding and enables the remaining seedling to develop a strong, healthy root system that supports lots of growth and fruit production.

Start thinning out when the seedlings have 2 sets of leaves. Use sharp scissors to cut away any excess seedlings, leaving the best one in place. Do not pull up the excess seedlings. This can disrupt or damage the root system of the remaining plant.

Transplanting Seedlings From Trays to Pots

If you have started your seedlings in trays, transplant them into individual 3 to 4 inch RAOOKIF Nursery Pots when they have 2 to 3 sets of true leaves. True leaves typically appear 10 to 14 days after germination.

Repotting the growing seedlings encourages a healthy root system and strong seedling to develop.

Fill the pots with well draining potting or seed starting mix.

Before transplanting remove any leaves from the lower part of the stem. Lower leaves contacting the soil can cause diseases to form.

To transplant, make a hole in the center of the soil filled pot. Remove the seedlings from the tray and plant in the hole. Gently firm down the soil and water gently with a spray bottle.

Use a spoon to scoop out the seedling and root system intact. Hold the seedling by the soil, not the stem. Handling the stem can cause it to snap.

10 Transplant tomato seeds

Transplant the growing seedlings into individual pots. 

When transplanting aim to keep 2 inches of stem above the soil line and bury the rest.

Don’t worry about planting the seedlings too deeply. Tomatoes can grow roots from any part of the stem that is buried. If you have leggy seedlings, transplanting them deeply helps to resolve the issue. Planting slightly deeper also encourages the plant to develop a large root system.

Transplanting into the Final Growing Position

By the time the last frost date arrives you should have some strong healthy seedlings ready for transplanting outside.

As our guide explains, it is important that you harden off the young plants before transplanting into the garden. An important part of growing tomatoes from seeds, hardening off helps the plants acclimatize to their final growing positions.

The process usually takes 7 to 10 days. Gradually increase the amount of time that the seedlings spend outside each day.

11 Prepare soil before transplanting
Prepare the soil before transplanting.  

During this period, take the time to improve the soil and prepare the planting position.
Wait for the last spring frost date to pass and for the soil to warm before transplanting.

Ideally nighttime temperatures should be consistently 60 ℉ or higher when you transplant. If you plant out in cooler temperatures your tomato plants struggle to settle or grow.

To transplant, dig hole twice as large as the pot the plant is sitting in.

Work some tomato fertilizer and good organic compost into the bottom of the hole. This helps the transplants to settle more quickly. Remove the tomato from the pot and center in the hole.

Cover the root ball with soil and firm down. Mulch the soil around the plant and water deeply. Do not allow the mulch to contact the stem.

This is also the best time to install a support such as a stake or a tomato cage if necessary.

12 Support tall plants
Taller varieties require support. 

Keep plants well watered for the first week to 10 days. This helps them to settle into their new position.

The transplanting process is exactly the same if you are growing in containers, raised beds or grow bags. Just make sure your chosen pot is clean, has lots of drainage holes and is filled with a well draining rich potting medium.

Tomato Plant Care Tips

Once settled in their final position, these are easy to care for plants. Whether you are growing outside, in a greenhouse or indoors, care is largely the same.

13 Tomatoes are easy to grow
Easy going plants, even minimal care is rewarded with a bountiful harvest.

The most important thing is to water and fertilize your tomato plants regularly. Irregular watering can cause issues such as blossom end rot to develop.

A good rule of thumb is to give each plant 1 to 1.5 inches of water every week. During hot spells you may need to water the plants more frequently. Plants growing in full sun also require more regular watering than those sitting in partial shade.

As the fruit ripens, reduce the amount of water you give. This concentrates the sugars in the plant, sweetening your fruit.

Be careful not to reduce the water too much. Too little water can cause the plant to wilt or become stressed. A stressed plant often drops its blossoms or fruit. A soil moisture sensor is a useful tool to help you get the balance right.

Fertilize your plants once every 2 to 3 weeks to ensure a good yield. A balanced product such as Espoma Tomato Organic Fertilizer is suitable for use on all types of tomatoes. You can begin fertilizing as soon as flowers start to emerge.

Pinch out and prune away any suckers that emerge in the joint where 2 branches meet. These won’t bear fruit and take away energy that could otherwise be used to produce or ripen fruit.

You can also remove some of the leaves to allow the sun to reach ripening fruit. But don’t go too crazy, leaves are vital for photosynthesis. If they are not present the sugars

that sweeten your fruit won’t develop.

If your fruit stays green for a little too long, there are a number of ways to ripen the fruit.

14 Master growing tomatoes from seeds
You can easily master the art of growing tomatoes from seed. 

Growing tomatoes from seeds is a pleasingly easy and rewarding process. Opening up a window to a whole world of different varieties, once you have grown tomatoes from seeds, you will never want to purchase transplants again.

Growing tomatoes from seeds 1 Growing tomatoes from seeds 2