A member of the rhododendron family, azaleas can be propagated in a number of different ways. Although propagating from seed is generally successful, vegetative propagation results in plants that produce flowers of the same color as the donor plant. Azaleas are very conducive to asexual vegetative propagation.
The most basic way of propagating azaleas is by seed. Because of genetic mixing, you can't be sure about the color of azaleas grown from seed until the bush produces flowers. Start your azalea seeds in the winter by planting them in peat moss as you would any other seed. Keep the soil moist and keep them in a warm, dark, area until they sprout. Once you see a leaf pair, start to slowly move them into full sun. Start with an hour and increase the amount of time in the light by a half hour a day until your azalea plants are accustomed to full light. Planting earlier in the winter will result in more hardy seedlings for outdoor planting in the spring.
Cuttings are another common way to propagate azaleas. Cuttings are a cloning method that creates a plant genetically identical to the parent plant. To root a cutting, cut a newly grown branch beginning in June. Cut the branch at a 45 degree angle when the wood is about half way between soft new growth and brittle old growth. Scrape off the bottom half inch of bark and root the cutting in a mixture of 50 percent peat moss and 50 percent perlite. Add rooting hormone according to manufacturer's instructions.
Some hard to root varieties may respond well to grafting. The precise grafting method will depend on the size and age of the cutting, but most grafting techniques can work. Grafting consists of making a cut in the trunk of a compatible rootstock and slipping a cutting into the cut so the cambium, or growing part of the wood, of the two pieces presses together tightly. Seal the graft with grafting tape or wax to allow the two parts to grow together.
Air layering is a technique for rooting new growth while still on the azalea. To air layer an azalea, make two circular cuts all the way around a branch. Make these two cuts 1-1/2 to 2 inches apart. Connect the two cuts with a straight cut and peel away the bark. Wrap the wound with with a handful of wet sphagnum moss. Seal the wound and moss in clear plastic using electrical tape to keep the moisture inside the ball. When you see roots appearing all around the moss, remove the moss and cut off the rooted branch. Plant the rooted branch in a pot.
To perform a mound layering, cut off existing shoots at six inches in the spring to trigger new shoot growth. In the fall, mound new, well-draining soil four or five inches above the old ground level. Keep the soil moist for a year and a half. Remove the soil the second spring after mounding to expose the base of the newly- rooted shoots. Cut the shoots off above the old ground level but below their root level and plant the newly rooted shoots.