AMES, Iowa – Plants can be propagated with several different methods. Many trees and shrubs in the home landscape can be propagated by hardwood cuttings. This type of propagation uses shoots of the previous year’s growth to produce new plants. In this article, Iowa State University Extension and Outreach horticulture specialists answer questions about propagating by hardwood stem cuttings.
Which plants can be propagated from hardwood stem cuttings?
Trees propagated from hardwood cuttings include many conifers, poplar and willow. Shrubs propagated using this method include blueberry, dogwood, elderberry, forsythia, hydrangea, rhododendrons and viburnum. Vines propagated from hardwood cuttings include bittersweet, Boston ivy, grapevines, trumpet vine and Virginia creeper.
Propagation is a great way to produce more of a wanted plant or to preserve a variety or cultivar with a specific form, color or size. However, some plants are patented and vegetative propagation on many of these cultivars is prohibited.
Where on the plant should the material from hardwood cuttings be collected?
Cutting materials should come from growth that was a shoot in the summer and has hardened off over winter. This is often referred to as one-year-old wood.
Cuttings from trees should be selected from specific locations on the plant. Shoots from the juvenile zone, which is the interior and lower part of the tree, are the best for hardwood cuttings. While this area is not the youngest part of the tree, it is juvenile in the sense that it generally does not produce flowers. Cuttings from this area are more likely to root. Select materials that had vigorous growth the previous season and thin, non-flowering buds.
Epicormic shoots (water sprouts) are often suitable for propagating because they are juvenile tissue with vigorous growth and are unlikely to flower. Use caution when selecting suckers from below ground or at the base of a tree as propagation materials. While these tissues are juvenile and similar to epicormic shoots, many trees in the landscape are grafted, and the suckers from grafted trees are likely from the rootstock and are not the desired cultivar.
When should material for hardwood stem cuttings be collected?
Material for hardwood stem cuttings should be collected in late winter when the plant material is dormant. In Iowa, the best time is late February or early March.
Cutting materials also can be taken in late fall or early winter after plants have gone fully dormant. This cutting material will need a cool treatment before being rooted. Store cutting material in moist media in a cool area (~32-40 degrees Fahrenheit) away from fruit, since the ethylene produced from fruit can have a negative effect on the cuttings.
What is the proper size of hardwood stem cuttings?
The length of most hardwood stem cuttings varies and is generally between 3 and 12 inches with a diameter ranging from ¼ to 1 inch. Cuttings with terminal buds are important in some plants, but for most easy-to-root plants, one long stem can be cut into several shorter cuttings. Each cutting should have at least two nodes. The bottom cut should be made just below a node and the top cut ½ to 1 inch above a node. (A node is the point on the stem where a leaf bud is attached to the stem.)
What is the procedure for rooting hardwood stem cuttings in a container?
Using a bypass pruner, collect the appropriate-sized cutting material from the juvenile zone of the tree in late February or early March. Be sure to keep all stems oriented in the same direction, as stems stuck upside down will not root.
Dip the base of the cutting into a rooting hormone. Insert the base of the cutting into the rooting media. Ensure that at least one bud/node is below the media and at least one bud/node is above the media. A rooting media of coir or peat moss-based mix with coarse perlite in a container with drainage holes is best. Lightly firm the material around the base of each cutting and water the rooting media. Let it drain for a few minutes and pour off any excess water in the saucer or tray to avoid saturating the media.
Covering the cuttings is generally not needed since they are dormant. Place the cuttings in bright light, but not direct sunlight. Inspect the cuttings daily. Remoisten the rooting media should it begin to dry out. Be sure not to overwater. Rooting should occur within six to eight weeks.
What is the procedure for rooting hardwood stem cuttings directly in the garden?
After gathering the cutting material, bundle the cuttings together (placing all the tops in one direction) and secure them with twine or rubber bands. Place the bundled cuttings in a plastic bag containing lightly moistened sphagnum moss or wood shavings. Store the cuttings in the refrigerator. Placing the cuttings in the refrigerator keeps the cuttings in a dormant state.
In early spring, as soon as the ground is workable, remove the stem cuttings from the refrigerator. Take the cuttings out of the plastic bag, dip the bottom of each cutting in a rooting hormone, and plant them in the ground. When planting the cuttings, make sure their top ends are pointing up. Completely bury the cuttings within an inch or two of the top bud. For many home gardeners, a good planting location would be at the end of a garden, as the site would be convenient and easy to maintain.
A consistent moisture supply is crucial to successfully rooting the cuttings. After planting, water the cuttings regularly in dry weather. Rooting should occur within six to eight weeks.