Joey Williamson, Ph.D.
Home & Garden Information Center
Growing new azaleas from cuttings produces plants that are clones (exact copies) of the parent azalea plant. Azaleas, as well as many woody plants, are normally propagated by stem cuttings, and the following describes how most azaleas can easily be reproduced.
The time of the season is important for the greatest success, and the azalea cuttings should be taken as semi-hardwood cuttings. This means that the spring flush of growth is complete, the leaves are fully matured and the stem doesn’t easily snap when bent. The semi-hardwood stem is at partial maturity (that is, somewhat woody), and this corresponds to mid-July through early September in South Carolina.
Cuttings should always be taken in the early morning from healthy, disease-free and insect pest-free azaleas. The parent shrubs should not be under drought stress, so be sure they are well-watered two days prior to taking the cuttings. Each cutting should be 4 to 5 inches long and taken from the ends of branches.
Cuttings can be placed in plastic food storage bags, and the bags labeled with the cultivar name and date. Put the bags immediately into a cooler of ice to prevent drying of the cuttings. These bags may be placed in the refrigerator if more time is required to set up the propagation containers and rooting media. Cuttings may be held as long as one to two days in the refrigerator, but do not add water to the bags as this may promote rot.
Various type of containers may be used to hold the rooting medium, but most importantly there must be drain holes in the container. Plastic gallon nursery pots, 5-inch pots, cell packs, or even the bottom portion of a plastic milk carton may be used. With the latter, be sure to cut several holes in the bottom for proper soil drainage.
Sterility of the containers is extremely important. Scrub used containers with soap and water to remove any old soil or soil mix, and then submerse the containers briefly in a 1:10 solution of bleach and water. This will kill any pathogens the containers may harbor.
The rooting medium must be well-drained. An excellent combination is a 1:1 mix of peat and perlite. Before filling the containers, wet this soil mix in a clean tub or bucket, letting it absorb water. This will ensure the medium is evenly moistened.
The cut end of each cutting should be trimmed making a fresh cut just below a node. The nodes are the points of leaf attachment on the stem. Carefully remove all leaves from the bottom one third of the cutting. Typically three to five leaves will be left on the cutting. To encourage more branching, the top or terminal one inch may also be removed. Remove any flower buds.
It may encourage faster rooting if the lower one half to one inch of stem is wounded on one side by scraping the bark off with a sharp knife. Wet the stem end of each cutting, and then roll the bottom one inch of the stem in a talc-based rooting hormone. Examples of rooting hormones are Green Light Rooting Hormone and Scott/ Miracle-Gro Fast Root Rooting Hormone. Tap off any excess.
In larger containers the cuttings should be spaced two or three inches apart. Use a dibble (or a thick marker or pen) to make individual holes in the rooting soil mix, and then insert the cuttings to a depth of about one third their lengths. At least one node must be beneath the soil. Firm the soil against each cutting and gently water to settle the soil. Fertilizers should not be added initially, but can be applied after rooting of the cuttings has occurred.
Initially the cuttings have no roots. To prevent the cuttings from drying out, the relative humidity must be kept close to 100%. This can be accomplished by placing a wire frame into and above the pot, and then enclosing the pot and frame in a white or transparent plastic bag. The wire frame may be made from straightened coat hangers. The wire frame prevents the plastic bag from touching the foliage of the cuttings.
Alternatively, the upper portion of a clear and colorless, 2-liter soft drink bottle may be placed over the cuttings in the pot. If cell-packs are used to hold the rooting medium for smaller cuttings, the cell-packs can be placed into a standard greenhouse flat, and the top of the flat covered with a clear plastic propagation dome.
Place all containers outside in bright indirect light. Do not allow direct sunlight to contact these miniature greenhouses as the cuttings may dry or get too hot. Inspect the medium every week to determine if additional water is necessary. With adequate soil moisture, there will be condensation on the plastic covering. Keep the medium moist, but not wet.
Within five to eight weeks the cuttings will begin to form roots. Check for rooting by gently tugging on the cuttings. If resistance is felt, the cuttings are becoming successfully rooted. Now that roots are present, the relative humidity can be lowered. Remove the caps from the 2-liter bottles, make slits in the plastic bag covers, and slightly prop up one end of the plastic propagation domes. This will help acclimate the young plants to the surrounding conditions. At this point, also increase the light level slightly by allowing the cuttings to be exposed to a couple of hours of morning sun. The young plants with roots can now be lightly fertilized. Use a dilute, ¼-strength liquid fertilizer on a weekly basis.
After another month, the cuttings can be completely uncovered and exposed to more morning sun. Check the medium often to be sure the young plants do not dry out. Larger containers will need additional water less often than will smaller containers or cell packs.
Plants can be separated and potted up individually in late summer. Overwinter the plants outside in a cold frame or protected area. Roots will continue to grow in the fall and the following spring. These plants can replanted into the landscape in the early spring, or held for additional growth in containers.
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This information is supplied with the understanding that no discrimination is intended and no endorsement by the Clemson University Cooperative Extension Service is implied. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.