Give Valentine's Day flowers a little TLC to last longer

To keep Valentine's Day cut flowers fresh, protect them from freezing temperatures outside as you bring them home and place them in room temperature water as soon as possible. With a sharp knife or pruners, remove a minimum of one inch from each stem with an angled cut. Ideally, make this cut while the stem is under water. Cutting on an angle increases the surface area for water intake.

Add floral preservative to the vase water. Most preservatives contain an acid (to neutralize alkaline tap water) and an ingredient to discourage bacteria. Remove all foliage below water level so it does not rot.

Cut flowers prefer a cool, humid environment and should be kept out of bright light and away from heating vents. Do not place cut flowers close to a bowl of fruit or vegetables, since the ethylene gas emitted by ripening fruit might damage the flowers. Cigarette smoke can also damage cut flowers.

• It is best to keep any logs you saved for burning in the fireplace outside until you are ready to burn them as insects can come in with the firewood. Never treat firewood with insecticides. Also, do not transport any ash wood outside of the emerald ash borer quarantine zone to avoid further spreading of this insect.

• When 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.