Illinois Ag Connection - Winter Considerations for Propagating Plants

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Winter Considerations for Propagating Plants
Illinois Ag Connection - 12/12/2018

Dormant winter pruning always leaves a mess of trimmings that end up being composted or placed in your yard bin. But there is another use for those trimmings: plant clones.

"Plant propagation is the science and practice of creating new plants," said Bruce J. Black, University of Illinois Extension horticulture educator. "Creating new plants can be done with woody trees and shrubs or softer, herbaceous plants."

When you take trimmings from woody species, keep only those that are healthy and show no disease, Black advised. Discard any pieces that are discolored, have spots, are soft or mushy, or are otherwise unhealthy.

Healthy trimmings should be bundled, kept in a cool location and not allowed to dry out. If you are going to wait until closer to spring to begin your propagating, find a suitable storage site. Refrigerators or coolers can be used, but it is best to avoid refrigerators that are also used to store fruits that produce ethylene (apples, cantaloupe, pears, etc.). The compound is a plant-ripening hormone that can affect storage life of plant materials and can speed up the growth of certain pathogens. Bundled trimmings can also be kept in an unheated, sheltered environment like a shed or garage.

Woody cuttings should contain four to six nodes on each piece. The length of the cutting will depend on the internode length, or the space between nodes. Internode growth depends on the growth rate for the plant and the weather.

Making cuts into the dormant wood is what starts the propagation process. Making the initial wound creates hormonal changes affecting growth and development. Follow-up cuts are usually made if you are going to graft or bud your cuttings to enhance their growth.

Grafting is putting two or more species of a plant together for enhanced benefits such as dwarfing, improved disease resistance, and cold hardiness. Budding is the insertion of buds or nodes of a plant into the stem of a rootstock plant. In both practices, the top portion of the graft or the inserted bud will be the desired variety you will see during the growing season, whether you chose it for its flower, fruit, or leaf.

"These two types of plant propagation techniques can be done during the winter and kept under growing conditions (temperature, light, humidity, etc.) depending on the species you are working with," Black said. "Grafting, budding, and plant propagation can be done on many types of plants during the winter, not just hardwoods."

High humidity and moisture are important during the post-cut and post-grafting periods. The scion portions (the part of the plant above the graft) are not receiving water since their xylem has been cut and they have no roots. Once the callus tissue seals the wound and the cambium connects between pieces, water and nutrient transportation will resume.

In the case of taking cuttings to create a new plant, high humidity is needed until adventitious roots form. "Once the cambium connects or adventitious roots form, reduce the humidity to normal growing conditions and resume normal watering," Black said.

Many Extension services have information on how to propagate plants. When working with a new plant, it is recommended to do your research into the best way to propagate and your plant's preferred care conditions. "Plant propagation is one of those fun sciences with rewards that keep on giving! Have fun and experiment with your favorite plant this winter," Black said.

For more information on plant propagation, check out the University of Illinois Extension's Vegetative Propagation of Houseplants at https://go.illinois.edu/HouseplantPropagation or the University of Illinois Extension Horticulture's Four Seasons Gardening Series -- Vegetative Propagation at https://go.illinois.edu/FourSeasonsVegetativePropagation.

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