Starting Tomato Plants From Seed

Starting Tomato Plants From Seed

Learning to start your own seed indoors is a great way to get an early start to gardening for the season. After a long winter, it's fun to start playing in the soil and experience a bit of sunshine indoors during the cooler season. Don't be intimidated by the thought of setting up your own small growing station.

There are many different products used by experienced gardeners or nursery growers such as heat pads, propagation benches, temperature controlled fans, pH meters, specialty lights, micro-nutrient solutions and more - but the truth is, this can tend to make things a bit more complicated than necessary when first learning to start seeds.

All you really need to start your own tomato plants are fresh seeds, soil, water and light. Take a minute to think about how plants start growing in nature, without fancy propagation products or even human intervention. These tomatoes pictured below were found growing wild in the forest, possibly spread by birds.

Wild tomatoes growing in forest

A tomato falls to the ground in the fall and starts to rot. The gel of the tomato which is a natural seed germination inhibitor, protects the seeds from starting to grow into a new plant too soon.

Tomato gel acts as a natural germination inhibitor


As the seasons change, the seeds lay on top of the ground rotting and eventually get covered by a blanket of snow where they patiently wait for a new growing season. In the spring, the seeds are carried away and spread by the runoff water as they skim across the soil until they get nested into a small crack in the soil.

Here they will lay dormant until they receive just the right combination of moisture, heat and light naturally. A seed has enough energy stored within itself to germinate. As long as it does not dry out during this delicate stage, it will form small roots that reach deep into the soil looking for more nutrients and water.

Sometimes the biggest hurdle when learning to garden is spoiling the plants too much with excessive moisture, fertilizer or heat. If you are worried about being able to help your tomato plants survive, look at these hardy plants that managed to survive and thrive without any assistance or special care.

Walmart parking lot tomato

Another healthy tomato plant growing in a railway track.

Train tomato

The leaves will form and grow up towards the light no matter where the seed is planted. As photosynthesis converts this light into energy, the plant grows stronger in an effort to mature and set more viable seed for another season. 

So how do we mimic this growing process within our home? At Heritage Farm we use the seeds that we had collected the previous season. They had been stored in a cool, dark, dry environment to ensure the germination rate stayed high. We use true heritage varieties and offer limited supplies of seed for sale through the online store. Our goal is to help others learn to save and grow their own heritage seeds to ensure these varieties survive for many more generations to enjoy.

Heritage Farm tomato seeds

We will recreate the ‘spring run off’ by planting our dried seeds in the soil or pellet growing media. By placing the seeds slightly below the soil surface, the goal is to have moisture touching all areas of the seed at all times. By having the seed coating softer, the plant will be able to emerge easier. 

In nature, it’s survival of the fittest. Some seeds get eaten by birds and rodents, some seeds are too deep. They may never grow or they lay dormant until they are moved closer to the surface where they will get just the right amount of heat and light to cue germination. Some will dry out from wind and heat before they have time to grow a strong root system. The goal of planting seeds indoors, is to create a controlled environment best suited for seed germination.

In the home we have pets or children bumping trays or moving the name tags ‘environmental impacts’, forgetting to water ‘drought’ or over watering ‘floods’ but for the most part, we can plant seeds into soil or media and mimic nature, indoors.

The seeding tray can be a nursery flat, an old milk container, recycled plastic containers or old pots. The goal is to contain the soil and not get the house too wet. Home gardeners will store soil in the fall to have available for early seeding. My grandmother used to use an old electric hot plate set up out on the porch to sterilize the soil before using it for seeding, while other pioneers placed soil in the oven or on the wood stove in a pot. They were attempting to kill any soil borne diseases that would keep the seeds from growing. This method can stink up the house pretty quickly too and not recommended.

Today we have seed starting soil available to purchase, and sterile peat pellets that expand when warm water is added. These products work great for starting the seeds, but keep in mind they lack nutrients (sources of food) for the seedlings once they start to grow. Do not add fertilizer at this stage. When the seedlings are large enough, they will be potted up with nutrient rich soil.

Once the seeds are planted just slightly below the surface of the wet soil, the trays can be moved to a warm area to germinate. To keep the newly emerging seeds from drying out, we place a layer of saran wrap or poly lid over the tray. This creates a small greenhouse effect and keeps water from evaporating before the seeds start to grow. This would be the hardest part to learn, but once you master this, you are ready to start any types of seeds. The soil should be damp enough that the seedlings do not dry out, yet the plant roots are not sitting in pooled water.

If the pellets were completely soaked in water for a few hours before seeding, there is enough moisture to last about a week depending on how dry the house is. The next watering is usually 2-4 cups of water in the tray so the pellets soak it up from the bottom vs. pouring water on top. As long as there are small water droplets of condensation on the plastic, there is enough water for the seedlings to get started.

Heirloom tomato plant started from seed

Lots of growers have great luck without grow lights, by keeping the pots in a window area. By turning them often, the plant moves back towards the light, which helps the stem grow stronger. This mimics an outdoor breeze.

It isn’t always necessary to have grow lights to start your seeds but if you do manage to purchase or set up a shelf and light system, it will definitely pay off in the first year. The goal is to have the light source as close to the plants as possible to deter long spindly plants that are weaker to transplant. If you have space in your home or basement, you can set up a shelf and hang a grow light. In the commercial nursery we have a great system of lights and heat sources, but some of our best plants came from our small hobby size set up here in the house sunroom.

Simple hobby grow lights for seed starting indoors

Once the seedlings are about an inch high, we take off the plastic to allow for more air circulation. This will deter rot and diseases while helping the plant grow stronger. When the seedlings have reached the two leaf stage, we ‘pot them up’ which means thinning or transplanting each tomato into a bigger pot where it can have more food and space to grow.

Be sure to sign up for our Farm Journal newsletter below to learn about the potting up stage for these healthy tomato seedlings you started from seed.

Heritage tomato seedlings

Heritage Farm is an educational nursery in Northwestern Canada that has been growing, saving and researching heirloom seeds and plants for generations. New growers learn about permaculture design, organic gardening and small farm living. We look forward to providing education, tools and resources as you begin your journey towards a sustainable, healthy, lifestyle.