What does hardening off even mean?

So you have grown your own plants from seed, or purchased young transplants from a garden center. Time to pop them into the garden, right? Not yet. There’s is one step that you shouldn’t skip, and that is hardening off your plants.

Your seedlings have been in a controlled indoor climate, either in your home or in a greenhouse, with no wind, extreme sunshine or cold nights to deal with. Hardening off is the process of gradually allowing your young plants to slowly get used to outdoor conditions.

The Hardening Off Process:

The process takes a couple of weeks, so start a couple of weeks before you plan to transplant outdoors. And this is not a strict schedule. You just want to get the plants outdoors for longer and longer periods each day, but keep an eye on them and make sure they don’t start to wilt. Also don’t set them out on very windy days. Keep in mind the soil will dry faster outdoors due to sun and wind so water more frequently.

Basic Hardening Off Schedule

  • Set your seedlings outdoors the first day for 1/2 hour in just partial sunlight in an area protected from the wind.
  • After your plants are outdoors for 1/2 hour somewhat protected increase the time daily to 1 hour, 2, 3, 4, leading up to 8 hours per day.
  • Then leave them out overnight in a sheltered spot (as long as there is no threat of frost).
  • After a couple weeks your plants should be accustomed to the outdoors and ready for transplant into outdoor containers or the garden.

Hardening Off Tip

If you have a lot of seedlings, place them in a cart or wagon. Then just wheel them into the garage overnight if it’s warm enough.