How to Harden Off Tomato Seedlings

If you are new to gardening you've probably heard others referring to hardening off their tomato plants and wondered exactly what they mean by this. Just as the name implies, hardening off is the process of strengthening plants (making them "harder")so they will be able to withstand the forces of nature once they are planted in the soil. Without hardening them off, you tomato plants are susceptible to sunburn and damaged leaves or breakage from the wind.

Things You'll Need

• Tomato Seedlings

Instructions

1. 

   Always ask the nursery or greenhouse attendant if the seedlings have been hardened off. Although some do harden off plants prior to selling, most do not have the room to do so. When in doubt it is always better to take the extra time to harden off them yourself.

2. 

   Place your tomato seedlings in a sheltered area outside for two or three hours for the first few days. An eastern exposure is great as it provides sunlight in the morning, but doesn't expose you tender seedlings to direct sunlight in the afternoon. A northern location also works well as the plants will receive some sunlight, but will avoid direct rays from the hot afternoon sun.

3. 

   Set them near a building or other structure that will provide a windbreak. The object is to get them accustomed to your climate gradually. Light breezes are actually desired as they will strengthen the stalks, but will not be so intense they will break tender shoots. If grass and other plants stir with the summer air it is ideal for the first few days of hardening your seedlings off.

4. 

   Gradually expose tomato plants to more sunlight for a few hours each day. Move them into a less sheltered area where they will be exposed to the natural winds in your location. Try moving them a few feet from the building for the first day or two and gradually move them into an open area.

5. 

   Monitor seedlings carefully for any signs of wilting. Exposure to the sun and wind dries the soil quickly. Provide fresh water and move to a shadier location until plants revive.

6. 

   Move plants inside at night for the first week. Once they have been hardened off and night time temperatures remain above 50 degrees it is time to plant them in the garden. Although many people set their plants out as soon as the danger of frost has passed, temperatures that drop below 50 degrees at night create stress for tomatoes and peppers and will inhibit growth. It is better to wait another week or two that to try to get a head start with early planting.

Tips & Warnings

• Hardening plants off gradually takes a week or more, but is worth the effort.