Late fall and early winter is the best time to take hardwood cuttings of certain woody plants (shrubs, vines and trees) to create replicas of them. This propagation method is especially useful for established desirable shrubs of unknown variety such as an old viburnum planted by a previous owner of the property or Grandma’s prized grapevine.
Hardwood cuttings are stems cut from woody plants that are given special treatment to get them to grow roots — thus making new plants identical to the one from which the stems are cut. Almost all ornamental woody plants in commerce are clones — propagated through hardwood or softwood cuttings to ensure that customers know what the plant they are buying will be at maturity.
Take hardwood cuttings after plants are completely dormant. Ideal stems for cutting are current year’s growth, healthy and straight. Look for the leaf nodes (points where leaves were attached) along the stem and plan to make the cut directly below one of the nodes. Many references suggest cutting where stems that are about the diameter of a pencil, which means length will vary by how much growth the plant has put on that year. Keep in mind that the size of the stem is less important than the maturity.
Remove the tip of the cutting also, with the cut made right above a leaf node. This cut can also be made in the pencil-diameter range but take care to remember which ends are top and bottom and that the remaining stem is long enough to plant.
Cuttings then go into the ground or into pots. If planting in the ground, dig a trench and set the cuttings in it standing up. Push soil up around the cuttings to support them or use sand or other material if desired. If planting in pots, fill pots with growing media and moisten the media thoroughly with water. Stick the cuttings into the media to the desired depth.
Over the winter, check soil and/or potting media periodically to ensure moisture is available. If soil or media becomes very dry, provide water.
In the following spring and summer, water and weed the cuttings as needed. Cuttings that fail to leaf out or show signs of stem rot during the season should be discarded.
By fall, plants should be rooted and ready to transplant into new locations.
Some species root better if wounded a little further or treated with rooting hormone. Wounding in this case refers to the practice of removing bark along the base of the cutting to expose internal plant tissues. Research plant species prior to taking cuttings to confirm specific requirements.
Cold frames and other similar insulating structures may also be desirable to maintain humidity and further encourage cuttings to produce roots, especially for certain species.
A few of the easiest species to propagate through hardwood cuttings that are common and appropriate for the Lawrence area are abelia, arborvitae, bittersweet, Boston ivy, boxwood, English ivy, forsythia, grape, some junipers, kerria, mockorange, rose, spirea, viburnum, weigela and yew.
One word of caution about propagation: Gardeners who aspire to profit from it may need special licenses to sell certain named varieties of plants. Plant patents and plant variety protection laws were created to allow the original discoverer or propagator of the plant some protection. Anyone interested in selling live plants or propagative material should research varieties and obtain proper licenses before entering commerce.
— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation.