Growing Tomatoes from Seed

Growing tomatoes from seeds are one of the most rewarding experiences as a gardener. Tomatoes are often the first crop new growers attempt to grow. They are a great crop for beginner gardeners to start with since they are easy to grow—with our pro-tips—and are so delicious when harvested fresh. When growing tomatoes from seed, there are a few things you need to be successful, and we are here to share them with you.

When do you start growing tomatoes from seed?

Growing tomatoes from seed is easy and allows you to access hundreds, if not thousands, of varieties of tomato seeds that are only available in seed form. Starting them at the correct time of year is the first step in successfully growing tomatoes from seed. You should start your tomato seeds 5–6 weeks before their ideal growing season, which is the time in the year when the air and soil temperatures are warm. Us growers in Zones 9 and 10 can start our tomato seeds as early as February! We have guides for each planting zone if you are wondering where and when to begin growing tomatoes from seed in your area. Not sure of your planting zone? Find out here by entering your zip code.

Once you know what planting zone you are in, you can refer to our zone-specific planting guides to start growing tomatoes from seed. See our planting guides for each zone here.

What is the best way to plant tomato seeds?

Tomato seeds are not fussy and can be planted in most soils with success. But for the quickest and most even germination, we recommend planting tomato seeds—or any garden seed—in a high-quality seed starting mix. Seed starting mix allows seeds to germinate quickly and easily. Tomato seeds should be planted at a depth of about ¼”. Like all garden seeds, tomato seeds need to remain moist the whole time to germinate. Using a high-quality seed starting mix will help by allowing the soil to stay moist yet aerated. Tomato seeds will germinate in 7-10 days. After they have grown their first set of true leaves, it is important to fertilize with an organic liquid fertilizer often to guarantee quick growth. Here are the products we love.

Great Big Tomatoes Compost Tea does so much more than add nutrients to your soil. This product adds essential microbiology to containers, raised beds, and in-ground gardens for happy plants. It helps grow the fungal and bacterial links in soil that are naturally missing, particularly when using bagged soil products. We loved the results from this compost tea so much that we now use it whenever we grow tomatoes, whether in the ground or a container! It works great for peppers too! The idea is simple. Great Big Tomatoes Compost Tea works in the same way that we use probiotics for healthy digestive microbiology. It helps soil thrive with all the organisms we can’t see while making nutrients bioavailable to plants.

Fish Emulsion, a somewhat stinky but oh-so-effective fertilizer, is our go-to in the garden for a host of reasons. We like that it derives from a natural byproduct of the fish industry and helps to use commercial bi-products that would otherwise be wasted. This product is not mined or taken from environmentally fragile areas. Additionally, fish emulsion is very mild, will not burn your plant, and is absorbed by the leaves and roots. This means you can be a bit willy-nilly with applying the fertilizer without concern for burning your plants.  For seedlings, we dilute it by half and use it every time we water to get our seedlings up and growing quickly.

Organic granular fertilizer is essential for adding nutrients back into the soil stripped from gardening over time. We like to use organic fertilizer because it breaks down slowly, will not burn plants, and is less likely to be washed away. We apply granular fertilizers between growing seasons on our farm to replenish what we have taken out.

Planting Tomato Plants Grown from Seed

Tomato plants will grow quickly and happily if given adequate light, moisture, and fertilizer. About 5–6 weeks after starting the seeds, your plants should have developed a good root system and healthy rootstock for transplanting. If the zone you are in experiences cooler temperatures, and you started your tomatoes in a protected environment, we recommend you harden them off for 1–2 weeks prior to transplanting. That can be as easy as leaving them outside during the most favorable time of the day to harden them off. This process helps to acclimate them to the outdoor weather, winds, and other conditions.

When you plant your tomatoes transplants, it is important to note that the tiny translucent hairs on the main stock are actually roots. Because of this, you can plant your tomatoes deeply with only 4–5″ of the plant remaining above the soil level. Planting deeply like this is particularly helpful for those growing in windy areas where plants are susceptible to wind damage. If planted deeply, your tomato plants can grow thick, strong stems and deep root systems, giving you an overall healthier plant.