Hardening off Hints

Our Swiss chard, broccoli, cabbage, and cauliflower seedlings all in a row

Our Swiss chard, broccoli, cabbage, and cauliflower seedlings all in a row

February 15 is the official “start date” for the cool weather planting season in our zone, a season that  lasts until about March 10 give or take a few.

Since such vegetables as broccoli, cabbage, and cauliflower don’t like to be sown directly, we start our transplants indoors right around the first of the year and try to  have them ready to set out some time around Valentine’s Day.

We have several irons in the fire at the moment, so we’re running a teeny bit behind, but this past week we began hardening off “the ladies” as husbie refers to them, to get them acclimated to growing conditions outside.

Here are a few things that have worked for us, and a few things we have learned the hard way:

1. Begin the process inside with a gentle fan.

This doesn’t need to be an elaborate set up.  If  you have a small desk fan or one of those tiny clip on models ~ great!  We don’t at the moment so we went with what we do have: an overhead ceiling fan in the office.  The fan creates a very gentle movement, simulating an outdoor breeze that will help the seedlings develop  strong stems.   We started doing this for a short amount of time each day or every other day once they got to be about 2″ tall.

2. Choose a day that is overcast with little wind.

Baptism by fire isn’t necessary and shock will only weaken the plants making them susceptible to pests and disease.  Introduce them to the elements gently.  Choose a cloudy day, or set them out in a shaded area.  Make sure there is only a little, if any wind.

3. Bring inside when they begin to show signs of stress.

That first day we set them out on a back porch and checked on them periodically.  As soon as they began to wilt a little, we brought them inside.  They lasted about 20 minutes, so we made a mental note to leave them out the following day for about 25-30, which brings me to my next point:

4. Leave out for a bit longer each day, gradually increasing exposure to the elements and sunlight.

The key word here is gradually.   Setting them out in direct sun for hours on end and expecting them to thrive, is a bit like teaching a small child to swim by simply tossing them in the deep end.

There are different ways you can accomplish this. I once saw a nursery cover their plants with shade cloth, uncovering the plants for a certain amount of time each day.  We prefer again,  to just go with what we have by setting the plants in dappled or full shade, and expose them to direct sunlight in growing increments of time.  When the plants can be left in full sun (or whatever exposure is required for them) for the full day, we go ahead and set out in the garden.

A few things to keep in mind:

*Morning sun is much more gentle than afternoon. When the plants are young, and we’re just beginning the hardening off process, I avoid  afternoon sun.
*Make sure they have adequate moisture before spending time outside.
*If you do inadvertently forget them, popping out to the back porch to unexpectedly discover a tray of wilted plants, they will most likely recover.  I have forgotten lettuce seedlings more times than I care to admit.

Hardening off Plants from Black Fox Homestead

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Hardening off Hints — 21 Comments

  1. I think the hardening off stage is where I fail every year. I tenderly plant the seeds and care for them inside. I delight in the sprouting and growing of those seeds, yet they seldom make it to garden transplants, or if they do, not for very long. We have lots of wind to tend with in the spring here in NE Texas. I’ve tried sheltering them from the wind when they are tender transplants but about 80% of the time they don’t make it past 2 weeks of planting. I’ll try to stick to your hardening off directions and see if I’m more successful this year. Thanks for this article. ~TMR~

    • We have a really difficult time with the wind too. In fact that has been one of our biggest challenges/adjustments thus far. I’ve heard of different ways to cope: planting taller plants around smaller ones, using sunflowers tall grasses, corn, etc. all of which we plan to try this season. Up to this point though we’ve had good success using floating row covers. We’ve managed to protect the sprouts we sowed directly and plan to put it over our seedlings immediately after planting. I purchased ours through Amazon but Growers Supply has some as well. If you can get a hold of some of that you might see how it works for you. Good luck! The wind can be frustrating. :/

  2. Great ideas! I used to just blow on them once or twice a day when they were really little, but the fan would be a great idea. I also use old windows as a kind of cold frame to put them into right away. We start our plants in March and maybe can put them in a cold frame in April. We don’t plant most things until May but of course we could if I were planting crops like yours. Thanks for sharing your ideas!!

    • I had a cold frame in our “city home” last year but we weren’t able to bring it with us. Maybe someday we’ll have one again. I really enjoyed using it and it did a great job.

  3. Wonderful information!. I’ve never had much of a green thumb, but I really want to have a better garden this year. Our average last spring frost is May 17th so I’ve got a few more weeks to plan and dream before starting plants. Thanks for the advice!

  4. I never knew that that wind is such a factor when I put my seedlings out in the garden. I will surely take more care this year when I put them out.

    • We have had soooo many problems with wind since we moved here. I didn’t know it could be such a problem either, but yes, it really can hinder your crops.

  5. Great advice – I’ve never used a fan before, but I love the idea. I’ll be featuring you tomorrow on my hop: :) Just shared on Facebook – have a wonderful night and week! – Gretchen

  6. never had much luck with starting plants from seed-until i started using a fan-my transplants look nearly as strong and healthy as the greenhouse grown ones at the garden centers

  7. Some great tips Jenny! My husband is the one that usually hardens our transplants but I am going to share your ideas with him. We have never used a fan that is a clever idea. Thanks so much for linking up to “The Ole’ Saturday Homesteading Trading Post” so glad you were part of the first day it was posted today!

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  9. Every hardening off article I’ve read deals with heat and wind. My last ‘bomb’ was with putting out seedlings for I crop I know to be frost hardy and then having them freeze. I still have no clue how one would ‘fix’ that challenge.

    • I have had to deal with too. :( The only thing I can think of that I would try would be to give them a “hardening-off phase 2″ so to speak and use plastic cloches or hot caps gradually increasing exposure but within the bed they are to grow. That is so frustrating when that happens.

      • I guess to harden for cold, you’d have to? bring them in later and later in the evening? If I put them outside, we’re having such nice weather, they’d be getting acclimated to heat, not cold.

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