Hardening Off

Hardening Off Seedlings in Alaska

The fastest possible schedule that works across all plants takes five total days. The first day outside is for 45 to 60 minutes. Day two and three are for two hours. Day four is four hours. Day five is eight hours. After that, the plants will be sufficiently hardened off and can live outside or in a greenhouse, so long as the temperatures permit.

The days you do this don't have to be contiguous, and you can skip a day or two to account for weather. If weather slows you down and you can't get your plants outside for several days, we'd suggest starting again with the same amount of time you used on the previous hardening off day. You might have heard you need to keep your plants in the shade in the beginning, that's a myth. Just keep it short in those first few days.

Our schedule can be extended a bit if you want to play it even safer. The biggest benefits will come with lower amounts of sun exposure. So, adding another day or two of one or two hour exposures in the beginning will provide maximum value and protection. Also, if you notice any sunburn on your plants (typically, white spots), it's vitally important to slow down the process. If we see this, we'll typically allow our plants a day or two to recover indoors before continuing with another sun exposure for an hour or two.

Hardening Off Schedule

Day   Outside Time (hrs)

1                  1

2                               2

3                               2

4                               4

5                               8