“Hardening-off” your plants is the process building your plants strength so you can move your plants outdoors. When plants or seedlings are grown or kept inside in a controlled climate, they don’t have the opportunity to develop the strength and structure to live out in the elements. They need to get acclimated to their new outdoor surroundings, to do this you'll want to gradually expose your plants for a portion of the day to slowly introduce them to the direct sunlight, dry air, and cold nights. Below is a step-by-step guide to hardening-off your plants.
#1 Over a 7-10 day period gradually expose your plants or seedlings to sunlight, cool nights and less-frequent watering . It is best to start on a mild weather day, starting with 1-2 hours of partial sun in a sheltered location. Make sure you protect seedlings from strong sun, wind, rain and cool temperatures. Bring your plants back indoors, each night.
#2 Begin to gradually increase exposure to sunlight 1-2 additional hours at a time and gradually reduce frequency of watering, but do not allow seedlings to wilt.
#3 After 3 - 4 days, move your plants from their shady spot into morning sun but return them to the shade in the afternoon. Too much direct sunlight can scorch the leaves of your plants.
#3 Keep an eye on your local weather especially the temperature prediction. If temperatures are predicted to be below the crop's minimum viability, bring your plants indoors. If temperatures remain warm both day and night, (at least 50F.), your plants should be able to handle the sun all day and stay out at night after about 7-10 days.
#4 After 7 -10 days your plants are ready to transplant. Try to do so on a cloudy day and be sure to water well after planting.