Monthly Book Giveaway - February 2023

Gardening #16: When to HARDEN OFF seedlings?


This is part 16 in a 16 part series: Gardening

From comfy cozy to the realities of life...

I start a lot of plants indoors in the spring and, as we enter the month of May, they are ready to get their roots planted into the earth and flourish under the rays of the sun. 

My seedlings’ home has been a consistent and comfortable 21c (70F) for their entire lives. Being tossed into the real world, with the fluctuating temperatures of the outdoors, intense rays of the sun, and, perhaps, the force of high winds, well, it will come as quite the shock and that shock could not only stunt their growth but, potentially, even kill them. 

Hardening Off

Hardening off is the process of slowly introducing them to the outdoors, letting them get used to Mother Nature and the reality of the outside world.

Hardening off can be a slow process, potentially taking a couple of weeks, taking them outdoors for only a couple hours at first and slowly extending their visitation times.

Personally, I’m not that gentle. Once they go outside, they are outside BUT I do cover them if they are getting too much sun, if it is really windy, or the nights are chilly. I also bring them inside if we are going to get frost.  I’m not that cruel!

Keeping an eye on the 10-day forecast, weather permitting, they will be going into the ground after a week of this transitioning.

This week, we are getting another week of rain and that means cloudy days - the perfect time for the transition to happen. They, at least, won’t have to deal with the intense heat of sun rays.

And, as of Friday, the forecast is that the nightine lows are starting to get above 4c - finally. That’s another important element of the hardening off process.

Nighttime Temperatures & Hardening Off

For me, nighttime lows is the key component to deciding when to take my seedlings outdoors

When the nighttime lows are 8C or higher, it is time to move the plants outdoors..

.. except for tomatoes, peppers, and watermelon. 
  • Tomatoes want the lows to be higher than 10C  
  • peppers like it even warmer, so I will be waiting for 12C for them.  
  • Watermelons also like warm temperatures, so they, too, will be waiting for 12C

Now, my temperatures aren’t quite reaching that 8C yet - but - I am taking my plants into the protection of my unheated greenhouse and this, hopefully, will make up for the difference. 

Predicted lows: 6C for the next 4 days and then it warms up 
I could just wait … but … I’ve got the gardening itch.

Today is the day

I have a digital thermometer in my greenhouse and I have it set to inform me when the temperature inside it reaches 70F - the temperature that the plants have been used to. 
This is when I will be moving my plants outside. 
And the journey begins! 

Currently (at 9 AM): 
6C outside
9C in the Hoophouse
🤞🏼 for warmer temperatures this afternoon

This is my first spring with my greenhouses/hoophouses so, again, this is an experiment. Crossing my fingers that my plan is a good one! 

I’ll keep you posted.
- Debbie, the impatient optimist 

My Weather: Zone 5b- 6

Predicted last frost date: May 24th (although, with climate change,  they are now saying May 4th)

May’s full moon: May 5 (the “old timer’s” sign for spring planting)

a simpler life