From Shelter and Into the Storm

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?

Gayla Trail
Gayla is a writer, photographer, and former graphic designer with a background in the Fine Arts, cultural criticism, and ecology. She is the author, photographer, and designer of best-selling books on gardening, cooking, and preserving.

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20 thoughts on “From Shelter and Into the Storm

  1. I tried hardening off my seedlings last year (complete novice) and killed an entire flat of beautiful peppers and tomatoes. So, this year, I started slow(er) and took my time setting out smaller batches of all of my plants. It made it easier that my mom bought a plastic “greenhouse” shelter for my Mother’s Day gift, so I have saved many more of my plants this year.

    I placed it in the back yard in the shade and it comes with a plastic cover, a completely black cover and a mesh cover to provide shade and allows air to come in. Chicago’s weather has been up and down, and my tomatoes are still not where I’d like them, but my pepper plants look great.

  2. Call me a lousy gardener, but with everything else in my life (I’m homeschooling 3 out of 4 kids), I don’t “do” hardening off. If I have started seedlings indoors (this year, I didn’t), they go out all at once on the first nice day. If the weather turns bad in the first couple of days, I will do my best to protect them. Otherwise, they’re on their own.
    I also overwinter plants indoors and do the same thing – pick a nice day in mid-May and send ‘em out. Perhaps to a shadier location than they might otherwise like, but perhaps not. Depends how much mental space I can devote to coddling them – usually, not much! I have done this for years with spider plants, aloe, cacti, rosemary, etc. along with overwintered peppers, fuchsia, mango and lemon trees, coleus, etc.
    The spider plants are in a spot that gets a lot of runoff from spring rains and they usually lose many tender “winter leaves” in the first few storms. The roots are strong, though, and the leaves invariably grow back better than ever.
    I believe in giving plants more credit and less coddling than most people, but I VERY rarely lose plants this way.

  3. The weather this year made hardening off tricky for me. All those overcast days and then *bam* a single cloudless, hot and sunny day just when I thought my seedlings were ready to spend the day outside spelled doom for some of my more sensitive (and valued!) little guys.

  4. Probably one of my least favourite plant related chore, so I’m kinda lazy about it. If it’s not nice out I don’t even bother taking anything out, but on the few nice days it’s warm and sunny I’ll sit plants out while I’m at work. Slowly, they spend more time outside in the evenings, eventually having their first “overnighter” after a couple weeks

  5. I’m starting hardening off by sacred basils. Tomorrow is their big day (well, one of) because they’ll spend the entire day outside. It’s like having a kindergarden on the balcony. :)

  6. I baby my seedlings less than you, and over the years my hardening off process has gotten pretty easy. I put them outside in the shade all day from the get go, then I shove them into the sunlight for a few hours the next, and by day three or four, all day in the sun. Once they’re ready for their first overnighter, they spend that night in the ground!

    I’ve heard that another method of hardening off is to restrict water until they wilt a bit, then water them. The act of wilting then perking up makes them tougher. On days that the weather is not suitable to put them out, I tend to do that, and they do seem tougher as a result.

  7. I started hardening off my plants on my deck about 3 weeks ago but there were days they stayed inside when it was too cold or rainy. It is like having a kindergarten! I transplanted some tomatoes and basil into pots this past weekend and they’re already growing taller and bigger. The transplants are now outside all the time except for the beans, which I still bring in at night. And I keep a close eye on the weather forecasts…

  8. Back in the day when I seemed to have more free time and less child and school related responsibilities, I took more time to harden off my seedlings… these days, I stick them out for a few days and in at night and after a week or so they were staying out all night…. I recently put out my tomatoes and some of my basil (even though I shoulda learned from last year to wait till June when my tomatoes sat through two (TWO!) snow storms at the end of May, gotta love southern Alberta!) and of course we instantly got cold, wet weather yesterday… oh well, they always bounce back… that’s the great thing about plants… they just wanna grow!

  9. I use a fan set on low while the tomatoe plants are growing and as the plants get bigger i open the window a bit. When i grew Tomatoes with out a fan the Hard on part was tricky maybe only 10 min out the first time because they where spindly, then increase from there. With the fan you can leave them out a couple of hours and increase to overnight a lot quicker.

  10. Last night i was watching t.v and it was raining pretty hard but i thought that my tomatoes and watermelons were going to be fine. Then i heard the tell tale sound of hale and my god did i ever hurry to get them inside! but most of my plants are ok the hale flattened my beans and peas though. But i really hope that the weather starts warming up!

  11. I started hardening off my tomatoes and peppers 2 weeks ago. On any night that forcasted anything below 10 c, I brought them inside for the night. I had everything in the ground as of 4 days ago. They are doing great and are bigger already. A few tomatoes I intentionally left ooutside on the cold nights, to see what would happen. Their leaves turned dry and crispy, but the plants have bounced back beautifully, with lots of fresh dark green leaves. Zone 6.

  12. I tried to grow indoor from seeds for the first time. I’m having such a hard time hardening off gradually. I feel like I’m failing at it a little. I work full time, often work evenings, often work Saturdays (and I adjust time off but I just have a weird work schedule). So my options are get very little evening sun or leave out all day and hope for the best. I’m going to be off Thursday-Monday so I might get a chance to do some more with the plants.

    As a working woman I just can’t figure out a hardening off schedule. :(

  13. I don’t know where Jennifer lives but I am in North Texas and have an approach more similar to hers. Like her I am astonished every time by how resilient plants actually are.

    As a rule the weather turns nice for the season here in April and so I planted seeds in pots right outside. This year has been more cloudy, rainy and severe in terms of storms than normal – but we always have some of that. Thus, the greatest danger is flash flooding a seedling in a small container, but if you are quick to drain it and re-steady its placement in the soil it is good within 24 hours. I did basil from seed this year and I have lost so few that I practically have a basil farm on the back patio. (Everyone I know will be receiving a fresh basil plant this year.)

    I do containers only because the quality of my soil is poor – drainage issues- but my mom used to just put everything in the ground and we had bountiful produce in the summer – by August neighbors were turning around when they saw us coming because they didn’t want any more yellow crook neck squash;-) I already have my first tomato – nearly tennis ball size -but our dearth of sunlight has prevented it from even thinking about turning red. It is looking good though so I will give it more time.( And sorry I am not so good at keeping track of the plants identity – I am sort of at the place where there are two varieties – edible/worth the trouble and… not so much:-)

    My big experiment this year was planting seeds that came straight from inside some of the expensive tomatos I bought at the grocery store. (free? seeds – they were expensive tomatos.) I did not know if they would grow at all, but they did. Then I wondered whether they would produce fruit at all, but yesterday I had 3 beautiful yellow blooms so it looks promising. The plant is healthy, if a bit “leggy,” but if I can stake it and get tomatos as good as the best they have at the grocery but better because they are straight off the vine I will be thrilled. I appreciate this inheritance from my mother – growing food – more each year. Best Gardening to each of you.

    p.s. I thought instead of “hardening off” they should call it “gardening off.” Ha – please forgive my simple attempts at humor.

  14. I went a little crazy with starting seeds indoors this year which caused me to move them into the ‘greenhouse’ at least a month ago. That’s what I tend to call ‘hardening off’ & I’m just in the last stages of trying to find homes for all those plants. Fingers are always crossed for at least the first week – rain? sun? birds? deer?

    My deck tomatoes are doing very well under their fish bag shelters – thank you very much!

  15. Hardening off? I live in North Idaho – I’m not even attempting that right now! I focus on the plants that will survive my climate with a survivalist attitude. A few tomato and pepper plants do choke my windows, though – here’s to hoping! But I am absolutely ecstatic to proclaim one of the great benefits of being up here: there are morels(!!!) growing in my backyard all on their own!!

    Every region has its charm! :)

  16. Ciao Gayla-

    What a crazy spring we’ve had this year, eh? I lost some early plants because of snow and not having raised bed hoop covers and planter covers in place. The chard had a tough early go, but they’re all doing well now and thank God I planted more than I had room for. Some varieties of Asian greens are less tolerant of being rootbound in cups and bolted well before they should have. Those will get re-sown as I try again to dial in their required planting regimen.

    Everything but the basil has either hardened off and is waiting for me to get around to planting it or is in the process. Most flats are currently in the garage for additional protection from the rain we got last night and today. I just planted my tomatoes on Tuesday AFTER the Monday thunderstorm that brought so much rain and wind. I wasn’t going to chance it. Beans just got planted and probably some of the cucurbits and corn will go in this weekend. The flowers get planted as their beds get weeded and my God, is it me or do the dandelions seem way worse this year? It’s all I can do to keep up with that!

    Because of the crazy weather, I probably won’t get everything planted until the 2nd week of June this year. I’ve started more things from seed than ever before (hard to imagine) and the weather just hasn’t cooperated well with my planned planting schedule.

  17. I’m a bad mother. The house is in Brooklyn and I live in Manhattan. Time constraints and limited supplies of time/energy – I just plopped the seedlings I managed to start under kitchen counter lights right into the raised garden bed.

    By the way, did you have your garden soil tested? I did a few years ago when I took over care of the old house and backyard. The test came back showing high heavy metal content and a NY Times article suggested urban gardeners planting edibles do so in raised beds with new soil.

    I do eat the figs off the old fig tree which was planted many years ago and continues to thrive and give lovely small figs in the late summer/early fall.

  18. Being a newbie gardener, I didn’t even know about hardening off until I read about it this spring, so it was obviously blind luck last year when I put out my bean and cuke seedlings and they grew like gangbusters with no coddling at all! Now that I know how I’m supposed to do it, my impatience is already getting in the way of doing proper hardening off…in/out every day for 2 weeks?! ;-) I think a mini greenhouse or cold frame is going to be the answer for me.

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