Hardening off. It sounds a bit dirty doesn’t it? Sort-of like “getting off” (see also “Back and Forth Forever“), but then when I think of the two acts, even just in terms of gardening, they are by comparison, practically opposites. One is about letting go of restraint, so to speak, while the other is all about withholding our desire to “just get those plants out there and into the garden already!” It is the impatient gardeners’ ultimate test of will and patience.
For those who are new to gardening, hardening off is the process of preparing your indoor-grown seedlings for life outside. Think of it like this: your plant babies have spent life so-far indoors underneath lights where it is cozy and temperature-controlled. There are pests and problems for sure, but for the most part life is simple and easy. There is no wind inside, nor is there pelting rain, chilly nights, blinding sun, or squirrels (sorry, hardening off can’t help with that). Thrusting your babies out into the big bad world in one go would be devastating to them. The sun alone would fry them to a crisp in no time.
And so, not unlike human children, we introduce them to the world and all of its joys (sunlight, beneficial insects, gentle breezes) and strife (see above) gradually, easing them into it as best we can. This means putting them outside, in a sheltered spot for short stints. Gradually, over the course of two weeks, we nudge them away from shelter and out into the storm.
There are lots of ways to do this. Cold frames and plastic greenhouse thingys are helpful. My friend Barry sets his seedlings behind an old window screen. The screening diffuses the sunlight. You can also make a tent from a newspaper to cover the seedlings with to a similar effect. I prefer to put mine out against a brick wall in a shady spot. The plants gain protection and warmth on one side from the brick. It helps if they are close to a door so I can pull them inside quickly in the event of a freak downpour or (god forbid) hail.
The trick is in remembering that while tomatoes and peppers are sun lovers by nature, they aren’t ready to be out in the sun just yet. Your plants will get there eventually, but if you don’t exercise restraint now, chances are good that you could lose the whole lot of hard won seedlings in one swoop if you expose them to too much, too quickly.
The Hardening Off Process
I put mine out slowly at first; an hour or so on an overcast day. Over time they stay outside for longer periods and eventually overnight. It’s okay to halt the process in the event of unseasonably cold weather, especially if frost is predicted. We’ve had some exceptionally cool nights and hard rains this year, and I’ve had to pull my plants in for a few days on a couple of occasions. The first batch are ready to stay out overnight, but they still need a bit more time in full sun before they’ll be ready to take their place outdoors for the season.
Therein lies another tip: Don’t try to harden everything off at once. I try to stagger seed starting as much as possible. Granted, different plants have different schedules, but I don’t do all of the same type at the same time. This year my tomatoes were done in two batches. So were the peppers. As a result, I have less plants at the same stage of development to harden off at the same time. If something goes wrong with one batch, I don’t lose everything at one time. It reduces the risk and also makes life just a bit easier.
Are you currently in the process of hardening off your transplants? How is it going?