Extension News

Ask the ISU Experts

Pink Poinsettia

Note to media editors: Got gardening questions? Call the Hortline at (515) 294-3108, Monday-Friday from 10 a.m. to noon and 1 to 4:30 p.m., or e-mail us at hortline@iastate.edu. For more gardening information, visit us at Yard and Garden Online, http://www.yardandgarden.extension.iastate.edu


How do you select and care for a poinsettia? 

Select plants with dark green foliage and brightly colored bracts.  Little or no pollen should be showing on the true flowers. (The true flowers are yellow to green, button-like objects located in the center of the colorful bracts.) Avoid poinsettias with wilted foliage, few or no lower leaves or broken stems. 

Before venturing outside, place the poinsettia in a plant sleeve or carefully wrap it to prevent exposure to cold temperatures. Exposure to freezing temperatures, even for a brief moment, may cause the bracts and leaves to blacken and drop. As soon as you get home, unwrap the plant and place it near a sunny window or other well-lighted area. However, don't let the plant touch the cold window pane.  Also, keep the poinsettia away from cold drafts or heat outlets. Poinsettias prefer temperatures between 60 to 70 degrees F.

Water needs can be determined by the finger test. Check the potting soil daily. When the soil becomes dry to the touch, water the plant until it freely flows out the bottom of the pot. If the pot is wrapped in decorative foil, punch a hole in the foil at the bottom of the pot for water drainage and place a saucer underneath the pot. Discard the excess water which drains into the saucer. 

Today, most florists use molded plastic pot covers rather than foil.  When watering these plants, carefully remove the poinsettia from the pot covering, water the plant in the sink, then drop it back into the molded pot cover. Both over- and underwatering cause problems for poinsettias. The lower leaves of overwatered plants turn yellow and drop. Dry plants wilt and also drop leaves. 

How can I prevent salt damage to trees, shrubs and turfgrass areas? 

Deicing salts (NaCl, CaCl2, KCl, and MgCl2) can damage landscape plants when excessive amounts accumulate in the soil. The most serious damage typically occurs near major streets and highways where salt from run-off accumulates in the nearby soil. Excessive use of salt by homeowners also can create problems. Trees, shrubs, perennials and turfgrass are susceptible to salt damage. Additionally, spray from passing vehicles can damage roadside plants, particularly evergreens.

Homeowners can minimize salt damage by using deicing salts prudently. Before applying salt, wait until the precipitation has ended and remove as much of the ice and snow as possible. Mix salt with an abrasive material. Fifty pounds of sand mixed with one pound of salt works effectively. Avoid piling salt-laden snow and ice around trees and shrubs.

While the amount of salt applied to major roadways cannot be controlled, steps can be taken to minimize damage. As soon as the ground thaws in early spring, heavily water areas where salt accumulates over winter. A thorough soaking should help flush the salt from the root zone of area plants. If possible, alter the drainage pattern so winter run-off drains away from ornamental plants. When planting trees near major streets or highways, select salt tolerant tree species.

How can I prevent my arborvitaes from flopping over during heavy snows? 

Multi-stemmed evergreens, such as arborvitae, can droop badly due to heavy accumulations of snow or ice. Susceptible evergreens can be protected by tying the stems together with twine, rope or strips of panty hose in fall. Carefully brush off heavy accumulations of wet snow by hand or with a broom. If ice accumulates on plants, prop up the branches to avoid breakage.  Don't try breaking off the ice. Frozen limbs and foliage are extremely brittle and attempting to remove the ice may cause greater damage. Promptly remove the rope or twine in spring. 


Contacts :

Richard Jauron, Horticulture, (515) 294-1871, rjauron@iastate.edu

Jean McGuire, Continuing Education and Communication Services, (515) 294-7033, jmcguire@iastate.edu

Three high-resolution photos of poinsettias suitable for printing are available for use with this week's column, including a larger version of the pink poinsettia thumbnail photo above [pinkpoint.jpg] 500K file; a red poinsettia showing several flower clusters [redpoint.jpg] 400K file; and a closeup of a poinsettia flower [redpoint2.jpg] 500K file.