How to Grow Heirloom Tomatoes from Seed

It’s so much fun to grow heirloom tomatoes and to taste and enjoy the different varieties.  

In this article I’ll take you step-by-step and show you how to grow heirloom tomatoes by seed.

But first… 

What’s the Difference Between Heirloom Tomatoes and Regular Tomatoes?

The tomatoes that we most often see in our grocery stores are bred for the sake of shelf life, disease control and uniformity. Many people (and restaurants) want to count on a certain taste or texture for the foods and recipes they make with tomatoes, which is understandable.

Even in the garden, we tend to plant the same types of tomatoes: Celebrities, Early Girl, Big Beef, Big Boy and Grape tomatoes.

But with this ‘mono-culture’ mentality, we lose out on enjoying the different flavors, textures, shapes and colors of the many varieties of tomatoes that are out there.  Variety is the spice of life, after all.

Heirloom tomatoes are non-hybrid tomatoes. They have not been crossbred. These varieties are at least 40-50 years old.  Many varieties have been passed on from generation to generation.

There are over one thousand different varieties of heirloom tomatoes out there!

What’s the Difference Between Determinate and Indeterminate Tomatoes?

Tomatoes, whether they are a hybrid or an heirloom, can be either a determinate or an indeterminate plant.

It’s important to know the difference so that you can decide what seeds are best for you.

A determinant tomato plant is one that grows to a determined height, and all the tomatoes come out at a certain time. This is usually a bush type of tomato plant. Tomatoes from a determinate plant will all ripen at about the same time.

An indeterminate plant will continue to grow until the plant is killed by frost. It is is constantly producing new growth and new fruit.  These plants need stakes or string to hold them up when they get larger.

Where to Buy Heirloom Tomato Seeds

I personally like the non-profit organization Seed Savers:

As a nonprofit, Seed Savers Exchange aims to conserve and promote America’s culturally diverse but endangered garden and food crop heritage for future generations by collecting, growing, and sharing heirloom seeds and plants.

Seed Savers Mission Statement

Here’s a short video about their seed exchange program:

Another option of course is to purchase Heirloom seeds on Amazon.  Here’s a nice variety pack:

When to Start Planting Seeds Indoors

Tomato seeds are usually started indoors, and are replanted and moved outdoors once they have established leaves and roots.

They should be started indoors about 4-6 weeks before the last frost.  In many states with freezing temperatures, this means starting seeds around tax day, April 15th.  Warmer climates can start as early as December.

How to Prepare Tomato Seeds for Planting (Indoors)

You can germinate seeds in any type of container, whether it’s a plastic cup, grow plugs, or even egg shells.

The container will need drainage, so if you are using a plastic cup or Styrofoam container, be sure to make a few drainage holes.

You’ll need a soil mix or peat pellets.

And, you will have to have a designated light source.  This can be a window that provides either 6 plus hours of direct sunlight. If you do not have a window that provides enough sun, you will need to use grow lights

Below is an excellent video with step-by-step instructions:

When to Transplant Tomato Seedlings from Seed Tray

Rule of Thumb: It’s time to transplant seedlings into a larger container when the height of the plant is three times the diameter of the pot.

For instance, if you have a seed tray with 1.8 -inch cells, you would want to transplant the seedling into a larger container once the plant is about 5-1/2 inches tall.

How to Germinate Tomato Seeds in a Paper Towel (Improved Method)

Another option to grow heirloom tomatoes by seed is to use the paper towel method.

Fold a wet paper towel around the seeds and place them in a baggy. 

Although this method works well, there are some downsides to it when checking for germinated seeds. It’s hard to open up and refold a wet paper towel … as you can imagine. Additionally, it can be a challenge to remove the germinated seed once it grows into the paper towel.

Here is an improved method, shown at about the 5-minute mark of this video:


At about the 9:30 minute mark of the above video, you’ll see how to transfer seeds to the soil once the seed has germinated.

How to Germinate Tomato Seeds from Sliced Tomatoes

Here’s a fun way to grow tomatoes using sliced ripe tomatoes:

How to Germinate Seeds Using Egg Shells

Tomatoes can develop blossom end rot, which happens when a plant does not have enough calcium.

When it’s time to transplant, you can bury the eggshell with its seedling directly into the pot or the ground.

How to Plant Germinated Tomato Seeds

Seedlings can be planted into the ground once evening temperatures are above 50 degrees and daytime temperatures are over 70 degrees.

Ideally the plants are about 6 to 10 inches tall.

This video shows how it’s done:

Where Do Tomatoes Come From?

Tomatoes originated in South America.  The Aztecs cooked with tomatoes.  The Spanish brought tomatoes to Europe at the time of the Spanish Conquest of the Aztec Empire.

Is a Tomato a Fruit or a Vegetable?

It’s technically a fruit.  And believe it or not, it’s actually a berry!   

In 1887 however, there was a legal dispute because vegetables had tariffs, while fruit did not.   

This dispute went to the Supreme Court in 1893, and it was decided thatthe tomato is a vegetable, based on the popular definition that classifies vegetables by use—they are generally served with dinner and not dessert.