Rocks for the Propagation of Daphne

Delicate Daphne

• There are several types of daphne. Winter daphne cultivars like “Aureomarginata” (Daphne odora “Aureomarginata”) are hardy in U.S. Department of Agriculture plant hardiness zones 7 through 9. “Silveredge” daphne (Daphne × burkwoodii “Silveredge”), named for white variegation along the tips of its leaves, is hardy in USDA zones 5 through 8. Daphnes are broadleaf evergreens that prefer partial shade and high amounts of water. They generally bloom in spring, although the timing varies depending on the species.

Pleased to Meet You, Perlite

• Although it looks like Styrofoam, perlite is actually closely related to rock. It is made from glass, which is a mineral. It occurs in nature as a volcanic glass and when heated to 1,600 degrees Fahrenheit, changes form dramatically. Akin to popcorn, it “pops” and changes from a glass particle to a light, airy substance roughly 13 times its starting size. This substance, while related to rocks, helps immeasurably with rooting plants because it allows plenty of oxygen as well as water to reach the developing roots of the cutting.

Rooting Medium Type

• Perlite makes a great rooting medium, but other rocks are used as rooting media. Sand, for instance, although it is so small it often doesn’t resemble rocks, is actually composed of ground-down particles of larger rock. Fine gravel is also sometimes used as a rooting medium. Peat, which isn’t a rock at all, is another common material. Mixtures of any of these substances will usually work well as a rooting medium. A half peat and half perlite mix is common, as is half peat and half sand.

Stem Cutting

• It is also important to cut the daphne at the right stage. Daphne should be cut when it is in the semi-hardwood stage, which is fairly far along in the season’s growth, usually around mid-July. Right after a flush of growth, when the leaves are about full-grown and the wood is somewhat firm but still pliable, is the best time to take the cutting. Take a several-inch length, trying to avoid any errant flower buds, though normally there won’t be any this time of year. If you must, remove them so that the plant will focus on developing roots rather than blooms.