Hardening off Tomato Seedlings Hardening off Tomato Seedlings

What You'll Need
Tomato seeds
Starter pots or trays
Lids or plastic wrap
Potting soil

Growing tomato plants is both a fulfilling horticultural practice and a way to supply your household with a fresh salad ingredient. There are two main ways for getting tomato plants started in the ground. The first is to buy pre-grown starts from your local nursery. Much of the work is already done when you go this route. You simply have to wait until the weather is warm enough, transplant them into the ground and maintain them. The other way is to grow the plants from seed. If you choose this method, the plants will require more early care to ensure they grow strong and healthy. There are several steps, and this how-to will walk you through the process from seeding, hardening off to transplantation.

Step 1: Plant the Tomato Seeds

The first step in starting tomatoes at home is to plant the seeds. To assist in seed germination, set the seeds in water overnight. Fill each of your starter pots or cells in the tray with high quality potting soil. In the middle, place one tomato seed about ½ inch below the surface, cover, tamp down gently and water. Don’t overly soak the starts, but make sure the soil is moist. Do this about 3 weeks before the last frost of the season and keep them inside.

Step 2: Maintain the Seedlings

Keep the starts covered with either a lid for the tray or plastic wrap. Place a few toothpicks at the edge of each bed of soil and lay plastic wrap over the top. The toothpicks keep it from suffocating the seedlings. Water daily, not enough to saturate the starts, but always keeping it moist.

Step 3: Transplant into Bigger Pots if Necessary

If it is necessary, you can transplant the tomato starts from the tray pods into larger pots. The tomatoes will be between 6 and 10 inches high when you put them in the ground. It is likely that the small pots will be too small after a while. Carefully remove the starts from the small pots or tray and place them into larger pots with fresh potting soil.

Step 4: Begin the Hardening Process

As the plants get bigger and the days get warmer, begin to harden the plants off. This is the process of putting the plants outside during the day and bringing them in at night. Hardening off the plants acclimates them to the outdoor weather. Tomato plants should not go into the ground until mid May at the earliest, otherwise they could get stunted. Put them outside everyday and bring them in at night for at least two weeks.

Step 5: Transplant Them to the Ground

After you have hardened off the tomatoes for a good two weeks, and when the weather is sufficiently warm, it is time to put them in the ground. Dig places for them in your garden bed and carefully transplant the mature starts into the ground. Tamp down the soil around the roots and water immediately. Put stakes or baskets around the plants so the tomatoes have something to support their eventual weight.

Hardening off your tomato plants is one step in the process of getting your home-started tomatoes into the ground and producing fruit. The first time you grow tomatoes–or any vegetable for that matter–there may be some uncertainty. Doing it yourself, though, is the best education, and next year you will be more confident. 

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