AZALEA PROPAGATION
Plant propagation is somewhat more difficult than planting a container-grown azalea. We have included a list of resource material at the end of this section that includes the sources of the information printed here.
You may root cuttings and grow plants many ways. Whatever method of propagation is used, sanitation and cleanliness is very important for success. The stock plants should be healthy, and the equipment used, the propagation preparation area, and the propagation area, greenhouse, or cold frame should be disinfected. Generally, most evergreen azaleas are easy to propagate. The problem is that not all species can be propagated using the same method. Each of the several methods of propagation have advantages and disadvantages. Azaleas are propagated from seeds, stem cuttings, root cuttings, layers, and grafting. Stem cuttings are the most popular method.
Seed Propagation
Propagation by seed is a good method for many deciduous azaleas and other cultivars that are difficult to propagate by cuttings or other methods. Seed capsules are green and turn yellow to brown when mature. Capsules should be collected when they begin to turn brown, mid- to late autumn. If the capsule has split open, seeds will readily drop out. Store the seed capsules at room temperature in paper envelopes or open-top containers. Each capsule contains 100 to 500 seeds. The seeds can immediately be germinated or stored at 20°F in an air-tight container for later use.
The sphagnum moss method is generally used for germination. Sphagnum should be shredded or milled, saturated with water, squeezed dry, and fluffed. The ideal container for germination would be a 3-inch deep, plastic container with a clear lid. Punch small drainage holes in the bottom. Rinse the container with a 10-percent chlorine bleach solution (1 cup bleach to 9 cups water) to sterilize the container. Fill the container to within 1 inch of the top with sphagnum. Scatter seeds over the moss and mist them lightly with water. Covering the seeds is not necessary. Close the containers and place them in indirect or fluorescent light. Keep the temperature between 60° and 75°F. Germination should begin within 2 to 4 weeks. Seedlings can be transplanted into individual containers or flats within 8 to 10 weeks.
Propagation By Stem Cuttings
Propagation by cutting is used most frequently for evergreen azaleas. Cuttings should be made from new wood (June and July) of healthy, mature plants. Suitable new wood should snap when broken. Cuttings should be 3 to 6 inches long with the leaves removed from the lower one-third to one-half of the cutting. Insert the cuttings 1 to 112 inches deep in the rooting medium. Rooting medium varies from (a) equal parts of perlite and peat; (b) 1 part peat and 2 parts perlite; to (c) bark, peat, and perlite. Before sticking the cuttings, the rooting medium should be thoroughly moist (not wet) and firm.
Flats or individual pots may be used, depending on preference or the quantity of cuttings. Azalea cuttings can be rooted outside in a shady area if humidity is high, in a greenhouse under a mist system, or under enclosed plastic structures in shady areas. Rooting will normally occur in 4 to 6 weeks. The problem in rooting all cuttings is trying to get roots initiated before the cuttings dry out. You prevent drying by increasing humidity, increasing shade, reducing air movement, and maintaining 100 percent humidity. Rooting hormones such as Hormex, Hormodim, Dip & Grow, and others also help in increasing the number of roots on the cutting.
Propagation By Layers
Layering is a modification of propagation by stem cuttings. It is a slow process, but it can be useful if the number of plants to be propagated is small. Branch layering is the easiest method of layering. A low, sweeping branch is selected and bent to the ground. A wound is made on the stem by making an upward cut 1 to 12 inches in length along the underside of the branch. The branch is buried 3 to 4 inches deep at the cut. The top of the branch is bent upward. The buried part of the branch should be pegged down with wire or a rock and covered with mulch. It frequently takes more than a year before the new plant can survive on its own roots. However, for the home gardener, this is often the easiest method to get a few extra plants.
Propagation By Grafting
Propagation by grafting is used in Europe, but it is not commonly practiced in the United States. It is frequently used to produce unusual plants, such as tree azaleas. Grafting is a means of propagation where a desirable bud or cutting (scion) of an azalea or other plant is attached to the roots or understock of a plant of a similar kind. The two parts join together and grow as one. The understock should be actively growing, but the scion should be dormant. A side graft is recommended, with the cambium layers of the understock (the light green tissue immediately under the bark) and scion matching before securing. Wrap the graft union with damp sphagnum. Cover the entire graft with a plastic bag. Once the scion begins to grow, gradually increase the volume of air by punching holes in the plastic bag. When the scion has hardened off, the top of the understock should be removed above the graft union.
To be successful, sanitation and cleanliness must be observed no matter which method of propagation is used. Remember, the stock plants should be healthy, and the equipment used, the area processed, and the greenhouse should be disinfected.
Source: http://www.aces.edu/pubs/docs/A/ANR-0200/prop.html
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