Master Gardener: Roses, house plants and poinsettias top the fall and winter care list

Chris Himmelwright
Pratt Tribune
Covering roses with mulch can help moderate the cold, but also prevents warm days during the winter or early spring from stimulating growth that is tender to returning cold weather.

Winterizing Roses

Though most shrub roses are hardy in Kansas, other types of roses can be more tender. For example, the hybrid teas have certain species in their ancestry that originated in the warm climate of southern China. These roses need protection to reliably survive Kansas winters. Mound soil or compost about 8 to 10 inches high around each plant. If using soil, bring it in from another part of the garden. Do not pull it from between plants because this can damage the rose roots or make them more susceptible to cold.

Mounding is normally finished by Thanksgiving. After the ground has frozen, add a 4-inch mulch of straw, leaves or hay for further protection. More soil may be spread on top of the mulch to keep it in place. Do not add the mulch before the ground freezes or mice may invade and feed on the roses over the winter. The purpose of these coverings is not only to moderate the cold, but also to prevent warm days during the winter or early spring from stimulating growth that is tender to returning cold weather. Excessively tall canes should be pruned to a height of 36 inches and tied together to prevent them from being whipped by strong winter winds. Wind can damage the crown of the plant or loosen the surrounding soil.

Next spring, remove coverings before new growth starts. If soil was used for mounding, remove from the area so that the level of soil stays constant from year to year. Compost can be spread out around the plant and used as a mulch. Wait until after the ground thaws, or the tops may begin growing before the roots can provide water.

Why Do Houseplants Lose Leaves After Being Brought Inside?

Newly bought houseplants or those brought in from outside often lose at least a portion of their leaves. In order to understand why this occurs, we need to look at how these plants are grown and what the plant needs to do to adapt to its new environment. Houseplants are normally produced either under shade outdoors in southern states or in greenhouses. Also, many homeowners move their houseplants outside during the summer. Regardless, the plants receive much more sunlight than they do in an indoor environment. Research done in Florida in the late 1970s revealed that tropical plants grown under high light conditions produce ‘sun leaves' while those grown under low light conditions have ‘shade leaves.' These leaf types differ structurally in that sun leaves have less chlorophyll (the substance that plants use to convert sunlight to energy) and the chlorophyll that is present is located deeper inside the leaf. Sun leaves also tend to be thick, small and numerous while shade leaves are more thin, larger, and fewer in number. When plants are moved from one light condition to another, they need time to adjust. This process is known as acclimatization. If they are forced to acclimatize too quickly, they will drop their sun leaves and produce a new set of shade leaves. If the acclimatization process is slower and less drastic, the plant can convert their sun leaves to the shade leaves that do better under low light. If going from shade to sun, this process is reversed.

Some houseplants are acclimatized before they are sold but many are not. So how do we help our new houseplants or those moved inside acclimatize to their new home environment? Houseplants should start out in an area of the home that receives plenty of light and then gradually moved to their permanent, darker location. This process should take 4 to 8 weeks depending on the degree of difference in light levels between the initial and final location of the plant. Remember, plants need to be acclimatized whether they are moved from a sunny location to one that receives less light or from shade to sun. Understanding plant processes allows us to anticipate potential problems. Acclimatization gives our houseplants a greater chance of retaining leaves instead of needing to be replaced altogether.

Poinsettia Care

Modern poinsettia varieties stay attractive for a long time if given proper care. Place your poinsettia in a sunny window or the brightest area of the room, but don't let it touch cold window panes. The day temperature should be 65 to 75 degrees F. with 60 to 65 degrees at night. Temperatures above 75 degrees will shorten bloom life, and below 60 degrees may cause root rot. Move plants away from drafty windows at night or draw drapes between them to avoid damage from the cold. Poinsettias are somewhat finicky in regard to soil moisture. Avoid overwatering because poinsettias do not like "wet feet." On the other hand, if the plant is allowed to wilt, it will drop some leaves. So how do you maintain proper moisture? Examine the potting soil daily by sticking your finger about one-half inch deep into the soil. If it is dry to this depth, the plant needs water. When it becomes dry to the touch, water the plant with lukewarm water until some water runs out of the drainage hole, then discard the drainage water.

* Adapted from the Kansas State Horticulture Newsletter by Pratt County Master Gardener Chris Himmelwright.