Hardening Off and Transplanting Seedlings

Seedling Photo by Brooke Coburn

It is time to begin to transplant tender seedlings outdoors, and seedlings that have grown indoors up to this point need special treatment before being planted outdoors. These seedlings are used to lower light levels, protection from the elements, and ample water. So they will need to adjust gradually to the outdoor environment, a process called hardening off.

Hardening Off

Photo Brooke Coburn

Shade for new seedlings by Brooke Coburn

About a week before transplanting, begin placing the seedlings outdoors for a few hours each day. Place the plants in a location with light shade and protection from the wind so as to avoid scalding and wilting. A shade cloth, tree, or trellis can provide adequate shade. Each day, gradually increase the amount of time the seedlings spend outdoors until they can be left out even overnight. Keep a careful watch on the weather forecast, however, and be sure to bring the seedlings inside if temperatures are going to dip near to freezing.

Transplanting

Transplant seedlings on an overcast, cool day, if possible, after the danger of frost has passed. Loosen the soil and dig a hole for the transplant. Carefully remove the seedling from the pot, keeping as many of the roots intact as possible. Place the roots in the hole and move loose dirt back around to support the stem of the plant. Water right away with a solution of half strength fertilizer. Keep newly transplanted seedlings well-watered for the first three to four weeks after transplanting until they develop a larger root system.

Summary

Gradually acclimate seedlings to the outdoor environment by providing protection from sun and wind. Transplant on a cool, overcast day, and continue to provide sufficient water until the root system has developed. See the links below for more information and to find your local frost dates.

Sources

Buying and Hardening Seedlings http://www.ext.colostate.edu/ptlk/1802.html

Hardening Off Isn’t Hard http://www.colostate.edu/Dept/CoopExt/4dmg/Garden/harden.htm

Vegetable Planting Guide http://www.ext.colostate.edu/mg/Gardennotes/720.html