Time to start growing your spring seedlings

It's not too soon to start annuals that get off to a slow start, such as pansies, violas, petunias, snapdragons and lobelia.

Petunias and lobelia will be best planted after the danger of frost has passed. While garden centers offer many favorites, the choices are seemingly endless when you grow your own.

Use grow lights to ensure success. A florescent type hung on a chain works best, as you can adjust the level to keep the light at an optimum 8 to 12 inches above the seedlings.

Providing bottom heat for the seedlings will also improve results. Heat mats or cables can be purchased at your local garden center.

Thin seedlings as needed, especially after the first set of leaves form, to prevent overcrowding. Keep the best plants. Be sure to sow a few extras, but not too many, to make sure you get the number of plants you intend to use.

• Keep watering any evergreens that are planted in outside containers when temperatures are warm and conditions are dry. Evergreens continue to lose water through their leaves during winter and can suffer damage to foliage or even die if allowed to dry out in the container. Watering during winter will generally improve the performance of your evergreens growing in containers.

• If healthy cut roses suddenly develop drooping heads, it may be due to air bubbles trapped in their stems. Float the entire stem in a sink full of warm water. Trim another inch from the stem, cutting on an angle below water level. Try to gently straighten the drooping flower head as the flower and stem continue to float and the cut end of the stem remains under water for at least one-half hour. When the flower head hardens to a straightened position, the roses may be placed back in the vase.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.