Let’s get into the meat and potatoes of hardening off! Like what’s going on and exactly how we do it.
So, the gist is that plants grown under indoor lighting don’t have sufficient protection from the sun’s strong light rays and intense UV light. We have to slowly introduce our plants to the power of the sun in order to give them a chance to build up those natural protections. You can almost think of it like the plant putting on sun tan lotion!
If you just radically shift your plants from indoors to outdoors, they will perish. So, this is a step you cannot simply skip. We have, however, spent a lot of time developing a “perfect” and fastest possible hardening off schedule that can possibly be achieved.
Our hardening off procedure is one day at one hour, two days at two hours, one day at four hours and finally one day at eight hours. After this, the plants can be outside. The key here are those very short early days, they must be very short. If you want to “improve” this schedule, more days at less time is where you want to adjust.
There’s a ton of “gardener’s voodoo” around hardening off. With a schedule like this, you don’t have to wait for cloudy days, put your plants under a tree or some of the other crazy stuff we’ve seen. Also, if you have to skip a day due to weather, pick up where you left off. If you have to skip several days, it’s best to repeat the last step.
Remember, we’re looking for days above 40 Fahrenheit for our cold hardy and frost tolerant plants. For those frost sensitive and warm loving plants, days above 50 degrees Fahrenheit are what we want.
We’ve tested this schedule for many years now, across hundreds of plant varieties. We do get a tiny amount of sun burn with this schedule on some plants, but it’s never enough to harm them. Again, the schedule can be improved with more days at less time, such as two days at one hour or three days at two hours. If you want to dive deeper, we have a full length article on the subject of hardening off, link down below!
