Starting Tomatoes from Seed.  
Hardening off Tomatoes before planting.  

by Karen of Love Your Land

hardening off tomatoes

Hardening off tomatoes before tossing them out in the garden is important... don't skip it!  What exactly does “hardening off” mean anyway?  Simply put, it is the process by which we help the young plants we have just spent weeks or months caring for adjust to the “real world” before we kick them out into it.  

If you start your seeds inside, there’s a very good chance you’ve spent countless hours whispering sweet nothings into your seedlings’ ears.  You check their moisture level every day or so, you do your best to give them as much light as they need, you transplant, feed, prune, you watch countless “Love Your Land” YouTube videos ... in short, you are invested.  And I believe, on some cosmic level, they are invested in you too.  But, like teenagers, while they may seem full grown, they’re really just tall babies.  They continue to need your guidance for a bit longer. 

So as the time for “planting out” in your area approaches, you may be wondering, “Do I just drag them all out and plant them after my last freeze?”  This is an option, of course, but so is not watering them, not feeding them, etc.  

What I’m getting to here is this ... your young plants and seedlings have spent their entire lives inside, where any wind or sun they’ve received has been diluted, filtered, or artificially reenacted in some way.  There is (hopefully) no rain or hail inside your home, your house probably doesn’t drop to 45 or 50 degrees at night, and it’s unlikely you have big fat birds flying around inside landing on your little seedlings’ branches. 

Rain, sun, wind, 20-30 degree temperature fluctuations ... these are all likely “real world” conditions for your little plants once they go outside permanently.  So, they need time to adjust.  

Think of it this way ... if you were going to run a marathon in a month, you probably wouldn’t sit around in your recliner until Marathon Day.  No, instead, you would exercise, condition, and train every day, so that when Marathon Day arrived, you’d be ready for the physical demands required to complete the run.  This is what your plants need. 

Basics of Hardening Off Tomatoes before you start them in the ground.

In a nutshell, about 2-4 weeks before the last frost in your area, you’ll want to start taking your plants outside for 1-2 hours per day.  After a few days, increase their “outside time” to perhaps 3-4 hours.  After a week or two, bump it up to 6-8 hours per day (weather permitting), and eventually let them have a “camp out” in the backyard overnight (as long as nighttime temps will not drop below 50 degrees).  


During the first week or so, make sure you are not placing your young seedlings in direct sunlight, and be sure to place them where they will be shielded from harsh, direct winds.  They’ll get plenty of sun and wind just by being outside in a sheltered, shaded location, but if you plop them right out in direct sun and wind, their delicate leaves will likely be sunburned and damaged, and direct wind could snap their young branches.  

After the first week, they can handle a bit more direct sun and wind, but keep an eye on them.  If at any point they seem stressed out, move them to shade.  If it’s particularly windy, move them back to a sheltered area, or even forego outside time that day if the forecast calls for hail or especially cold temps.  And pay special attention to their water needs, as they tend dry out much more quickly when they’re outside.  

Tomatoes sheltered on a porch.
Wind coming along? Cover them up with a bit of plastic.

That, my friends, is all there is to it.  After 2-4 weeks, your plants will be sufficiently “hardened off,” and ready to be planted outside in your garden! 

One last thing.  I can’t end this little love note to you without reiterating what may seem obvious to some.  Please do not forget to bring your plants inside at night during the first week or so, and anytime the forecast calls for nighttime temps under 50 degrees.  I have a ton of seedling pots, and quite honestly, sometimes I find it a bit of a hassle dragging them out and back in every single day.  But I do it anyway, because I would never forgive myself if I left them out overnight and the temperature dropped into the 30s while I lazily snoozed away.  

And finally, know that you do not have to be the perfect “seedling-hardener-offer.”  If you miss a day here or there, or you leave them out just a tad longer than you know deep down you should, do not despair.  We’ve all done it, and they will be just fine.  

(But promise me you won’t leave them out overnight if it’ll be under 50 degrees.)

Happy Spring, Everyone!!! 

Karen/Love Your Land

How Sharon is hardening off tomatoes in her garden. 

Sheltering your tomatoes when hardening off can come in many forms.  Be creative!  My husband built me this handy box with a freebie window he found.  Works a charm.  BUT be sure and don't put them out until it is warm enough at night.  The temps have dipped a little below that 50 degree mark for me and my tomatoes did fine... but early on when it went waaaay below... I lost some.  

Also with a set up like this, watch those daytime temperatures.  It can get mighty hot, mighty quick.  I prop the window open full or when I just need a bit of ventilation a small board props the lid open just a few inches. Works great.  

As you can see some of my tomatoes have out grown the box and are hitting the top. Time to trim or plant!
Be sure and open the box during the day. Temperatures may cook your plants.

About Karen

Karen is a wife, mother, business owner, gardener, canner, and the owner of “Love Your Land.”  

Karen understands that gardening in Northern Colorado is seemingly a fleeting moment in time, so join her on Facebook for daily tips, tricks, and discussions, and on Love your Land You Tube for weekly how-to videos on how to extend a 3-month grow season into a 9-month grow season! 

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