GROW YOUR OWN, Spring
Hardening off and transplanting your seedlings
May 10, 2022
It’s springtime and if you started your seeds indoors, you’re probably very excited to move them to that perfect spot in your garden.
But because seedlings are fragile plants, they will need a little time to adjust to a move outside. You will need to harden off your seedlings so they can adjust to an outdoor growing location.
Hardening off is the process of introducing young seedlings to the outdoor elements. This process typically takes place over several days up to a week.
Things to consider when getting started
GRADUAL INTRODUCTION TO SUNLIGHT
Indoor seedlings grown using indoor lighting will need some time to adjust to much stronger outdoor sunlight. Too much direct sunlight can cause bleached, curled leaves, or even loss of leaves. So, the introduction to the sun needs to be a gradual process.
CHANGING WEATHER
Spring temperatures can go from brisk cold evenings to warm sunshine during the day. Seedlings may experience stress with temperature swings. They will need to be sheltered from strong winds and inclement weather.
GENERAL TEMPERATURE FOR HARDENING OFF
It is safe to start the hardening off process at nighttime temperatures of 10 degrees C (50 F) or above.
Steps for hardening off of your seedlings
DAY 1 – INTRODUCE YOUR SEEDLINGS TO THEIR FIRST OUTDOOR EXPERIENCE
Choose a warm day above 10 degrees C. Pick a protected shaded spot that is relatively wind free. Leave your plants outside for 2 to 3 hours. Bring the plants back inside for overnight. Be sure to check their moisture levels as they may have dried out somewhat being outside.
DAY 2 – INCREASE THEIR TIME OUTSIDE WITH SOME PARTIAL SHADE AND DIRECT SUNLIGHT
The next day- weather permitting – bring your plant trays out and place them in partial shade to full sun for a few hours. Return them inside for overnight.
DAYS 3 & 4 – LET THEM SOAK IN THE MORNING SUN AND PARTIAL SHADE A LITTLE LONGER
On days three and four, bring your plant trays out for some morning sun for about 4 hours and then move to partial shade. Keep an eye on them to make sure they do not dry out too much from the sun. Bring them in for the night.
DAY 5 – LET THEM SPEND THE WHOLE DAY OUTSIDE
On day five your seedlings can experience full sun and partial shade and gentle breezes. Bring them in for the night.
DAY 6 – ALL DAY EXPOSURE AND OUT ALL NIGHT
After hardening off for five days your seedlings should now be ready for a full day and night outside. Just be sure to check the overnight weather is set to stay above freezing. You may want to also keep them off the ground to keep little pests like mice and moles from snacking on them.
DAY 7+ – TRANSPLANT THEM TO THEIR PERMANENT LOCATION
Your seedlings are ready to be transplanted. If possible, choose a somewhat overcast day to transplant so they are not shocked by intense sun. Water thoroughly after transplanting.
Keep a close eye on them for the next few days to make sure they are not overexposed to harsh weather or heavy sunlight.
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