How to Harden off Seedlings

Someone once said to me that I can't transplant seedlings until they have their second sets of leaves, the last frost has passed and the seedlings have been hardened off.  What?  I'm impatient as it is (ask any family member) so the fact that I have to continue to wait to transplant my already growing seedlings until the last frost AND they had a second set of leaves AND have been hardened off was a bit much to take.  Anyhoo, for those of you who have ever wondered what a second set of leaves looks like here you go (those are Dragon Egg Cucumbers, by the way): 

Now, the hardening off part of your seedlings require dedication and are the steps you want to take AFTER you have a second set of leaves.  Get ready for a bunch of "dont's". Sigh.

1. Take your seedlings to a protected location outside for one hour on day one every day for 7-10 days. With each day increase their time outside by an hour.  Day 10, they should spend almost the entire day outside.

2. Don't put them where wind will smack them.

3.  Don't put them in direct sun.  Start with shade. Gradually introduce them to sun.

4.  Don't start putting them outside until the temperatures are generally above the high 50's.  Some crops can handle colder weather, some cannot.  

5.  And for god sake, don't leave them outside overnight.  Temperatures are still chilly!

Here are recommended minimum temperatures for hardening seedlings off:

Hardy Crops: 40 degrees:  Broccoli, Brussels sprouts, cabbage, onions, leeks and parsley

Half-Hardy: 45 degrees: Celery, lettuce

Tender:  50 degrees: Squash, pumpkin, corn;

60 degrees Cucumber and 65 degrees Basil, tomatoes and peppers.

Now, I'm told that today is the first day of Spring.  Which means I SHOULD be able to transplant my cucumbers outside this weekend but I may schlep them in and out of the house for the next two weeks rather than running the risk that they will not make it due to the weather conditions.  As the saying goes, we will play it by ear.

Happy gardening!


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