Q & A "How and why should I 'harden off' plants?"
Hardening off is a process that helps plants acclimate as they move from a protected greenhouse environment to the more demanding one in your garden. Start by placing plants outside in a protected spot without too much direct sun or wind. Each day, move them out to a more exposed position. If it gets below 40 degrees at night, bring them inside. Water thoroughly as they dry out during this time. At the end of the week, they are ready to plant. For annuals, harden off your plants 7-10 days before our last frost day (mid-May) and they'll be ready to go when planting is safe. Hardening off really helps—it lessens a lot of transplant shock. You can do "reverse hardening off' in fall as you bring plants inside, gradually acclimating them to lower inside light levels.