One week before planting outside, the hardening off process is started. Gradually acclimatize the transplants from a warm, comfortable indoors to the cool, windy outdoors.  Place plants in the sun for an hour the first day, gradually increasing the exposure for about a week until plants can accept a full day of direct sunlight. Make sure the transplants are well watered during the process. After a couple days of full days outside, the plants should be left out overnight, unless there is a danger of frost.