How To Harden Off Seedlings

Moving young seedlings (and houseplants) that have been growing inside your home to a garden outside can be a traumatic experience for them. Outdoor environments bring fluctuating temperatures, rain, wind and humidity. If the plant isn’t prepared for conditions such as these, they may not survive their new outdoor environment.  The good news is that you can harden off plants beforehand to make the transition smoother and less stressful.

Start Early

Ideally, you should begin hardening off your seedling about 10-14 days before you intend on transplanting them. As long as you are consistent, this should be more than enough time for the seedlings to adapt to their new outdoor environment. Certain plants may transplant more efficiently with a longer hardening phase. Check your seed packet or look for more information regarding the hardening process.

Place Seedlings Outside

When you are ready to begin the hardening phase, start by placing your potted seedlings in a shaded outdoor area for about 45 minutes to an hour each day for the first week. During the second week, increase this amount to 2-3 hours of outdoor exposure. This will give your plants the opportunity to gradually grow accustomed to their new environment without simply being thrown in.

Giving young seedlings too much sun exposure may cause them to go into shock. Instead, place them in a shaded area like a covered patio or porch where they aren’t bombarded by full sunlight. During the second week, you can move them out into a full sun area for part of the time while they are outside.

If the weather begins to go south while your seedlings are outside, bring them indoors. Heavy rainfall or strong gusts of wind could damage an otherwise healthy seedling.

Transplanting

After two weeks of hardening, your seedlings should be ready for transplanting into the garden. Handle the seedling with care as you remove it from its container.