Cut flowers will brighten up the winter home

When buying cut flowers, I always take a close look at the flowers to make sure they are fresh. Avoid buying bunches that have flowers with brown edges or petals that are starting to fall off. To keep cut flowers fresh, place them in room-temperature water as soon as possible.

Protect the cut flowers from exposure to freezing temperatures outside. With a sharp knife or pruners, make an angled cut and remove a minimum of 1 inch from each stem. 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.

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 can damage the flowers, as can cigarette smoke.

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 a half-hour. When the flower head hardens to a straightened position, place the roses back in the vase.

• Continue cutting buckthorn out of native and cultivated garden areas during the winter. There will be less impact on herbaceous plants when this work is done on frozen ground.

Be sure to treat stumps with an herbicide such as glyphosate or triclopyr herbicide to kill the root system. Glyphosate needs to be used at a high enough concentration to work as a stump treatment. Some recommend a 50 percent concentration, but Chicago Botanic Garden staff has had success with a lower concentration of around 30 percent.

Among the drawbacks with glyphosate are that it is water based and will freeze during cold weather and that it is only effective on the cut surface. Triclopyr is the preferred method because it is oil based, effective through the bark and on the cut surface — and will not freeze.

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