How to Harden Off Vegetable Plants.
Front Yard Garden Update

As you know, I was once married to a stuffed animal. No wait. Wrong story.

As you know, I’m growing my own vegetables from seed this year. I ordered a bunch from Cubits and Twig & Tree and hoped for the best about a month and a half ago.

Right about Easter as a matter of fact, I got out all of my soil, pots, and seeds, threw the grow lights on and got to work.  I planted heirloom tomatoes, basil, Amish Cockscomb and a few other things including sweet potatoes.

So far so good as they say.

In less than 2 months I am now preparing my plants for their big move from a cramped condo with artificial lighting to their spacious new home with lots of natural sunlight and a really great landlord, I might add.

It’s now time to harden off.   Hardening off is getting your plants acclimatized to their new environment.  You can’t just take a plant you grew indoors and throw it outside and wish it well.  It will up and die on you immediately.  And then it might punch you in the nose.

For your plants to grow up into healthy happy, vegetable producing adults, you need to harden them off.  I keep saying harden.  Heh.

Basically all you have to do is take your plants outside for a few hours, increasing their time spent outside by a few hours, every day for around a week.

Everyone does it a bit differently, but this is a hardening off schedule you can use because you don’t have any other friends to help you with hardening. Off.


  • Day 1 – Set plants outside in the shade, protected from wind and direct sunlight for 3 hours.  Bring  inside.
  • Day 2 – Do the same for 6 hours.  Bring inside.
  • Day 3 – Do the same for 9 hours.  Bring inside.
  • Day 4 – Set the plants where they get a little less shelter for the day.  A tiny bit of breeze and sun can hit them now.  Not for HOURS and HOURS.   1-2 hours in a partly sheltered area.  Bring inside.
  • Day 5 – Same as Day 4, but allow 1-2 hours of direct sunlight.  Bring inside.
  • Day 6 – Allow the plants a bit more sun than they had the day before.  (allow them to stay outside all night for the first time unless it’s unusually cold.
  • Day 7 – Set the plants out so they’re in the sun most of the day and leave them outside at night again.
  • Day 8 – Plant your plants outside.  (do NOT plant outside if frost is still a possibility)


A tip for keeping your tomatoes frost free courtesy of the Good Dr. Richardson, is to do as the Mennonites do.  Plant your tomatoes really deep and if frost is expected just put a plastic bucket over each of them for the night.  Those Mennonites.
You can extend your hardening off to 14 days as well to be extra safe and sure.
This is especially important for things that aren’t in love with the cold.  Like tomatoes.  I grew a few varieties this year. And many of them.  Too many.  Wayyyy too many.  I will be giving away a LOT of tomato plants once they’re hardened off.  One goes to the Good Doctor for his excellent Mennonite bucket tip.


I’m also growing one flower.  Cockscomb (Celosia).  This Amish cockscomb is also a heritage seed which I bought from Linda at Twig & Tree.  Which, for some reason, whenever I type it out, I type Twit & Tree.
Once it blooms, Cockscomb looks like this.  I figured, if I was going to grow one flower, given my newfound hobby of hen farming … Cockscomb was the way to go.

 photo via Twig & Tree (where I ordered this seed from)


Also grown from seed, Acorn Squash.



Several Basil plants which I’ve already pinched back to promote bushy growth.


And then there’s the Great Sweet Potato Slip experiment.    Around the same time I started my tomatoes I started sweet potato slips.  I experimented with about 6 sweet potatoes all bought at different places at different times.
3 of them look like this.  Nothing.   Not a root, not a sprout, nada, nothing.  Zip.


One sweet potato is barely trying to sprout.


The much heralded “Organic” sweet potato isn’t doing much better.  So much for that theory.


Finally, there’s this great big mother of a sweet potato.  It’s got sprouts coming out in all directions and they’re just starting to grow really quickly.
These will be the slips I plant, plus the white organic sweet potato if it ever amounts to anything because it’s a different variety.  I’m not sure what this big one is, but my best guess would be Beauregard.


And finally … a look at what is probably the most impressive thing from my garden yet.
Asparagus.  Which I was assured wouldn’t be ready for cutting for at least another year or two.





Ahem.  Cough, cough.



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  1. Jen says:

    This is why your sweet potatoes won’t sprout:

    • Karen says:

      Hi Jen. Yes, I’ve seen that video. It’s cute! However … what’s funny is contrary to popular belief organic vegetables are sometimes sprayed with sprout inhibitor. That’s the thing about organic. It’s not “completely” regulated. My organic sweet potato isn’t doing nearly as well as my non organic. They’re a real crap shoot these sweet potatoes. ~ karen!

  2. Nicole2 says:


    Thank you for sharing your advice on how to harden my cockscomb. Seems I’ve been doing it wrong all these years….

  3. Gayla T says:

    This is so exciting! I’ve long since gotten over the thrill of it all. Just as in bringing human life into the world, baby plants are a miracle. Actually,it’s a miracle if you don’t kill them but I guess that’s true of the human variety now. If you are not home to harden your plants, look into a cold frame with a timer. They are a bit pricey but last the rest of your life. Actually, Karen will know how to build one on a post in the future, I’m sure. Making the little motor might be a stretch but you could buy one and still have a good tutorial. Mine did not actually last my life but died in a hail storm. I’ve only ever grown a sweet potato to entertain kids since I’m not a fan of eating them. I just figured you cut them up and planted them like Irish potatoes. Live and learn said the old dog.

  4. Karol says:

    Wow! I had no idea people had to go through all this crap to get plants to grow. Here, we just stick them in the ground and we’re good-to-go. I say “we” as if I am participating in plant growing. Ha! “not I” said the pig.

  5. Evalyn says:

    The bucket acts as a hotcap, which is a little paper dealy you can buy at gardening stores. -OR- you can cut the bottom out of a plastic jug large enough to fit over the plant, leaving off the lid, and it will act like a little green house to keep the nasty frost off your tender little sprouts. Remove at first light to prevent par-boiling.

    Sweet potatoes are finicky, persnickety, selfish little organizms. They sprout when and if they are damn well ready. *cough* In my opinion.

  6. Liz says:

    How long did it take your sweet potatoes to sprout after they developed roots? I have two that have had roots for a couple of weeks now, but no sign of a sprout.

    • Karen says:

      Liz – It depends on the sweet potato. I’ve found they’re incredibly random! I have a few with big sprouts and hardly any roots at all. Like 2 o 3 inch long roots. I have one that had all kinds of roots and just 3 nubs of sprouts. Well all of a sudden, one day those nubs of sprouts grew about 4 inches! If you’re anxious, make sure you get some black plastic cloth to put down where you want to plant the sweet potatoes. If you do that for at least a week prior to planting your sweet potatoes, it’ll get the ground nice and warm and help speed up the growing. You can actually plant any length of slip. The longer the better, but a 1″ slip broke off one of my plants and I stuck it in some dirt under my grow lights and it grew away like normal. ~ karen!

      • Liz says:

        Thanks! I wasn’t really expecting any hope of growing sweet potatoes in my northern Sask climate but I was hoping for some decorative vines for my flower pots. Can you please just clarify the slips?
        Is it just the vine that’s broken off the potato? or do you have to cut out a bit of the potato to include with the vine? and do you have to root the slip in some water before planting it into the soil? or do you just simply stick the broken off vine into some soil and it will grow? I’d REALLY appreciate some clarity on this (not that I’m paranoid of failure or anything :)

      • Karen says:

        Liz – You just break the “slip” off where it meets the potato. No need to gouge any potato out with it. Some people root it first, but you can definitely just stick it in dirt. That’s what I’ll be doing. ~ karen!

      • Liz says:

        Thank you ever so much!

  7. Nancy Blue Moon says:

    You are telling a lie again..aren’t you young lady??? Bless you Betty..It must have been so hard to raise that one…

  8. Shauna says:

    I suppose those of us who work full-time cannot ever grow plants from seed unless we take a week off to make sure we harden our plants correctly:(

  9. Deborah says:

    LMAO….this post gives a whole new meaning to the words “FOOD PORN” ! My tomatoes, tomatillos and variety of herbs are outside on Day 5 of hardening…really, really, REALLY want them in the ground before Thursday as we are heading up to the cottage for the loooooooong weekend! My peppers I am taking with me for the ride as they are still too delicate for the great outdoors….AND….pretty nifty getting the asparagus to grow in no time flat! :P

  10. Claudine says:

    Great post. My tomatoes are out for their second day, acclimatizing to life in the garden.
    I’ll have to check out the cockscomb. That is beautiful. I had to go back and check it out after reading the “inflamed lady parts” comment. Too funny.
    Thanks, as always.

  11. AmieM says:

    HAHAHA! I love the asparagus photo.

  12. Sarah in Illinois says:

    Thank you for the hints! I have killed SO many tomato plants in the hardening stage!

    And do tell how you manage to grow your asparagus so orderly and uniform! ;)

  13. Lisa says:

    I bought some cockscomb at the local farmers market last year but failed to ask what it was! It was pretty and different and I loved it – glad to know what it was now! I’m still so jealous of how big your seedlings grew – gotta look into that light! All of my plants have been in the ground (here in Northwest, Indiana) for a little over a week now and so far so good! Can’t wait to see your progress.

  14. Langela says:

    Don’t forget to plant your tomatoes up to their first “true” leaves. They will grow roots all along their stem and this will help your plant get strong. I put mine in the ground, put a coffee can around it, and fill it up with soil up to the true leaves. I also put a milk jug, with the bottom cut off, on the top of the can. This creates a greenhouse of sorts and gives them a jumpstart at staying warm and moist. Also, I just learned this year that your tomato seedlings need breezes to help them strengthen their stems. A light fan on them in the house or a breeze outside during hardening off will help. They also need calcium to keep blossom-end rot away. You can crush eggshells to powder and put them in the hole when planting. Powdered milk will also help. Are you tomatoes indeterminate? Most heirlooms are. If so, be prepared for them to get 10 foot tall or more. Ours last year got about 14 foot high. It was our first year planting them, so we were unprepared for the staking needed. We only had stakes up to 8 foot.
    Your seedlings look awesome, Karen!

    • Karen says:

      Um. What? LOL. A 14 ft. high tomato? LOL. I’ve never heard of such a thing. I knew all the other stuff but … A 14 FOOT HIGH TOMATO? ~ karen

      • Lisa says:

        In Chicago, my heirlooms would probably reach 8-10ft, if I didn’t cut the tops off. The stems are too small to hold an heirloom, even if one grew to maturity. I top them down to about 5.5-6ft every year.

      • Langela says:

        Indeterminate makes them more of a vine than a bush. Determinate means they have a somewhat determined height. My plants’ stems hold them up just fine, as long as they are staked. I’ve not tried topping them. Will have to research that this year.

        Just so we’re clear, Karen. It’s a 14 foot high tomato PLANT. Not a 14 ft high tomato. :) I don’t want you planning any city wide tomato canning events.

      • Karen says:

        Hah! ~ karen

  15. Barbie says:

    PS: We have always used a LOT of celosia “coxcomb” in the dried floral industry…it is sturdy and dries really well….you should cut and dry some for using later in some arrangements. We spell it differently, but I think there are a couple of different spellings. :)

  16. Debbie from Illinois says:

    Just wondering if you “harden off” that Cockscomb with the Fella’s help???? Bawawawa!!!! I crack myself up!

    Debbie from Illinois

  17. Barbie says:

    OMG! I just woke up my WHOLE HOUSE at 5:27am laughing at that last picture! LOLOLLOLOL

  18. I am excited about your garden as well as mine but this was a great piece of information and thank you so much for sharing…

  19. marilyn says:

    my garlic is growing!!!

  20. Melody Madden says:

    We have asparagus as well but the stalks are no where near as thick as yours .. Sigh. What does it mean to pinch of basil?

    • Karen says:

      Melody – You just pinch off the top pair of leaves. This promotes the growth of two new pairs of leaves on the plant. Pinching back makes your plant bushier and sturdier and bigger as opposed to taller and spindlier. You can pinch back all season long. ~ karen

  21. Ann says:

    It takes forever to get a sweet potato to sprout and give up useable slips. And then a very long warm growing season. Good luck with that one, sis!!

    • Karen says:

      Ann – Yes. That’s why I started the slips in March. I also have black ground cloth down to warm up the soil they’re going into. It actually isn’t unusual at all to grow sweet potato slips in my area. ~ karen

  22. Laura Bee says:

    All this talk about hardening, cockscomb & then the big purple heads on the asparagus. This post should have a R rating. As for my garden…still haven’t started my seeds. Can I just shove them in the ground, or am I screwed?

    • Karen says:

      Laura – I’m not sure if you need advice or if you just wanted to say “screwed”. It depends on your plant and where you live. A lot of things (like carrots, radish, beets, spinach, peas) are direct seed. Meaning, you don’t start seedlings, you just put the seed directly in the ground. Other things like peppers and tomatoes well yes. You’re screwed. Just go buy some plants at the nursery. ~ karen

  23. Moe says:

    Thanks for the schedule.. the odd time I tried to start flowers from seed, they turned into pitiful spindly little critters who shriveled up immediately when introducing them to the outdoors. Of course I put them in direct sun for the entire day.(dumba**) I probably still won’t attempt it ever again, but it’s nice to know why I failed. :o) Wish I lived closer, I’d love to have a tomato plant. That one I might try. I love fresh tomatoes, beat store brand every time.
    Absolutely love the font on your photos.. would you share what it is?

  24. karenagain says:

    Well, I’m trying this whole gardening thing too. I think so far it’s cost me several hundred thousand dollars. But that’s okay because it will save me soooo much in the long run. AND, it’s going to be so much better for me because I am organic. I swear that once my little sprouts start growing I will sit out there with a gun and shoot every deer, bug, dog and bunny that comes within two feet of my garden. And then I will eat it.

    Your asparagus is really coming in good this year. Most people wait to rubber band until the second year. I like that you threw caution to the wind and banded early. I’m just worried about the effects this might have on future propagation. J/K I have no idea what that even means.

  25. Lindsay says:

    Lol at the asparagus. And the cockscomb looks like something that would benefit from the infamous “frozen yogurt tampon.” It just looks really angry, red and swollen….

    • Karen says:

      Lindsay – OMG. That’s disgusting. Where have you been?! :) ~ karen

      • Lindsay says:

        A lady never tells. I can only hope when it blooms you think of me. Or inflamed lady parts. Which ever.

        This has gone too far. Lol.

    • Kirk says:

      Googled ‘how to harden off vegetable seedlings’ and your site was first on the page. The look appealled right from the get go. Not sure if dumb guys are supposed to be reading your info but I don’t care. I was not only enlightened but highly amused. Not sure if I’ll be as motherly gentle in hardening off my little green babies but I’ll be gentler than otherwise would have been. Who knew asparagus shoots came with their own rubbers!!!

      • Karen says:

        Hey Kirk! Really? This came up first? That’s kind of shocking. What with me just putting this post up less than 24 hours ago. Humph. I guess I’m an Internet sensation. Who the hell knew! Yes. Dumb guys are totally allowed to read the site. Many, many dumb guys do. Glad you found me! ~ karen

      • Kirk says:

        Ya…my baby Sugar Peas are happy I found you too although they didn’t specifically say so…kids these days. Should of left em out all night and then maybe they would have whined ;)

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