Spirea Propagation Methods
Why buy spirea from the nursery when it can be propagated in the home garden? Although the process of propagating spirea is a bit time consuming, it isn’t particularly difficult. Here are some of the most common spirea propagation methods.
Propagating Spirea from Hardwood Cuttings
Spirea is a woody landscape plant that is best propagated using a type of stem cuttings known as hardwood cuttings. The best time to make the hardwood cuttings is when the shrub is in the dormant period - late fall after the first hard frost or early winter, or in early spring.
According to gardening experts, spirea cuttings can vary in length from 4 to 24 inches, depending on variety. Most, however, will probably be in the 4- to 10-inch length. Make the cuttings in the early part of the day. As for which part of the plant to choose for the cuttings, always aim for the upper area of the shrubs. Avoid those that have spindly or weak stems as well as those with vigorous growth.
Making the Cut and Storing or Planting Information
Slant the cut below a node with a clean, sharp knife. Aim for a 4-inch length for each cutting, especially if making numerous cuts. If the cuttings will be stored over the winter, experts recommend tying them together and placing in a cool, moist environment until the following spring. Place in a water-filled bucket and cover with plastic, store in a nursery cooler, a cellar or basement where temperatures remain about 40 degrees, or bury them outside in sawdust, sand or sandy soil (place them upside down to encourage rooting at the base). In the spring, cuttings stored outside can be directly planted in soil, right-side up.
Cuttings from easily reproducing plants such as spirea can be wrapped in plastic or heavy paper with lightly moistened peat moss and stored in a cool place (40 degrees) until spring.
When planting cuttings, garden experts recommend setting them in the soil with the top up and at an angle of 45 to 60 degrees. They should be buried to within 1 inch of the top. In addition, use a rod or other garden implement to make the holes, so that the roots won’t be damaged when placing them in the soil.
Keep the newly-planted cuttings protected by a shade material such as a burlap screen during the first growing season.
Spirea from softwood cuttings can be taken in the spring and summer from new growth. Strip off the lower leaves and dip the cutting in rooting hormone and place in planting medium such as vermiculite or construction-grade, coarse sand. Cover with plastic and keep moist. After cuttings have rooted (roots are about 1-inch in length), they are ready to be transplanted to other pots with a growing medium.
Propagation by Division
Another method of propagating spirea is by division, which should be done in the fall or during the dormant period. Due to the fibrous root structure of this woody plant, a hatchet or shovel may be required to cut through the clump. Be sure to trim back the shoots and cut off any damaged roots before planting.
Dividing spirea may be desirable after several years when the shrub has become firmly established and may be overgrowing its surroundings.