For most gardeners, as the cold weather moves in, it means a long rest period before next spring arrives. However, some start scouting, planning and propagating deciduous plants and narrow-leaved evergreens. Hardwood cuttings from these plants are taken during the late fall or early winter after a hard frost when the plants have become dormant.
Hardwood cuttings taken from deciduous woody plants are those made of matured, dormant, firm wood after leaves have fallen. Suitable plants include privet, forsythia, wisteria, willow, poplar, honeysuckle, crape myrtle, grape, spirea, etc. The use of hardwood cuttings is one of the least expensive and easiest methods of vegetative propagation. Hardwood cuttings are easy to prepare, are not readily perishable, may be shipped safely over long distances if necessary, and require little or no special equipment during rooting. These types of cuttings are also easily transplanted after rooting.
The propagating material for hardwood cuttings should be taken from healthy, moderately vigorous stock plants growing in full sunlight. The wood selected should not have abnormally long internodes or be from small, weakly growing interior shoots. Generally, hardwood cutting material is ready when you can remove the leaves without tearing the bark. Wood of moderate size and vigor is the most desirable. Tip portions of shoots are usually discarded because they are often low in stored carbohydrates and commonly contain unwanted flower buds. Central and basal parts generally make the best cuttings.
The length of these cuttings may range from 4 to 24 inches, though most are 8 to 10 inches long. Diameter varies from ¼ to 1 inch, depending on the type of material to be propagated. At least two nodes are included in the cutting. The basal cut is usually just below a node and the top cut ½ to 1 inch above a node. Hardwood cuttings will desiccate, so it is important that they not dry out during handling and storage.
As mentioned, cutting material is gathered during the dormant season, it is then wrapped in newspaper or slightly damp peat moss in a plastic bag and stored at 32 to 40o F until spring. The cutting material should not be allowed to dry out or to become excessively wet during storage. At planting time, the cuttings are made into proper lengths and planted into a field nursery propagation bed without intermittent mist or in propagation flats with a very light intermittent mist.
Stored cutting material should be examined frequently. If signs of bud development appear, lower storage temperatures should be used, or the cuttings should be made and planted without delay. If buds are forcing out when the cuttings are planted, leaves will form and the cuttings will die due to water loss from the leaves and depletion of stored carbohydrate reserves prior to rooting.
Like deciduous plants, most narrow-leaved evergreens are propagated using hardwood cuttings. The difference is, the foliage of narrow-leaved evergreens is retained when propagated. Narrow-leaved evergreen cuttings must be rooted under moist conditions that will prevent excessive drying as they usually are slow to root, sometimes taking several months. In general, Chamaecyparis, Thuja, and the low-growing Juniperus species root easily and yews root fairly well, whereas the upright junipers, spruce, hemlocks, firs and pine are more difficult. There is considerable variability among the different species in these genera regarding the ease of rooting of cuttings. Cuttings taken from young seedling stock plants will root much more readily than those taken from older trees.
Narrow-leaved evergreen cuttings ordinarily are best taken between late fall and late winter. The cuttings should be taken from terminal shoots of the previous season’s growth and should contain a small portion of year-old wood at the base with the leaves removed from the lower half. Wounding will help the rooting of some narrow-leaved evergreen species. IBA is recommended in the range of 3,000 to 8,000 ppm quick dip using Hortus IBA Water Soluble Salts or Rhizopon #2 or #3 for the easier to root material and up to 10,000 ppm quick dip for harder to root cuttings. Cuttings are usually best rooted in a greenhouse or polyhouse with high light and under high humidity or very light misting, but without heavy wetting of the leaves. A bottom heat temperature of 75-80oF has given good results. A 1:1 mixture of perlite and peat moss is a good rooting medium. Some individual cuttings take longer to root than others. The slower rooting ones can be inserted again in the rooting medium and eventually root.
Hardwood cuttings taken from deciduous woody plants and narrow-leaved evergreens open up a whole season of possibilities for the novice and expert gardener alike. With time and patience, you will have beautifully propagated shrubs or trees. What are you waiting for?
Hartmann & Kester’s Plant Propagation Principles and Practices