Answer: Successful rooting of rhododendron cuttings is somewhat variety dependent and takes patience, says Bob Carlson, owner of Carlson's Gardens, growers of more than 1,800 varieties of rhododendrons and azaleas in South Salem, New York. You should take your cuttings in fall, and it will be more than a year before new plants are large enough to be planted in the landscape. In September or October, select a one year old shoot with no flower buds and take a cutting two to three inches from the tip of the shoot. Remove all but the top three or four leaves. Cut the remaining leaves in half with a scissors and cut the base of the stem at a 45 degree angle. Double wound the cutting by making two half inch slits just above the base on opposite sides of the stem. Dip the cutting in a rooting hormone and place it in a pot filled with a mix of one part peat to two parts perlite. Water the cuttings well and construct a clear plastic tent over the pot, using sticks or wire hoops so the plastic doesn't touch the leaves. Grow the cuttings on a heating pad (70_F bottom heat) and with artificial light through the winter, watering when the top inch of soil dries out. Check them for root development in a couple of months by tugging gently on the stems. If you're going to be successful, the cuttings will have begun to root by then, says Carlson. In spring, plant the rooted cuttings in four or six inch pots and grow them in a shady location outdoors, keeping them moist and protected form the wind. Thefollowing winter either heel the pots into the ground or transplant the cuttings into a cold frame, says Carlson. The next spring, plant them into the landscape. Carlson says some varieties of large leaved rhododendrons, such as Roseum Elegans, Boulede Neige and Cunningham's White, are easier to root than others. The red flowered varieties such as Nova Zambla are more difficult, says Carlson.
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