Azaleas are beautiful shrubs that have clusters of flowers ranging in pinks and blue shades. Azaleas are classified as rhododendrons. Under this name are now included, not only the evergreen kinds which have large, leathery leaves, but also the deciduous or leaf-losing varieties. Azaleas, which flower in spring or early summer, may grow only 18 inches tall or attain a height of 15 feet or more.
The soil for azaleas should resemble, as nearly as possible, that in which they grow naturally-a cushion of acid leaf mold. It should have a large content-60 to 90- per cent of organic matter. This may be leaf mold, peat moss, humus or decomposed pine, hemlock or spruce needles,or a mixture of any of these. Good quality soil and a little sand should make up the rest. I also have some interesting articles on planting shrubs that might be helpful.
Azaleas are “surface rooters”, but you should give them at least 18 inches of this compost and a good mulch of partially decayed leaves so their roots will remain cool and moist during the hot summer months. They should also have mulch in winter as a protection against severe cold. Most azaleas grow naturally in light, open woodlands or on the fringes of the woods. If shade is too heavy or too continuous, they will not flower freely. On the other hand, they do not like the scorching heat of summer and they insist on having their roots cool and moist. Place them where they will receive some shade or in an area to the north or northeast of the house where they will receive some sunlight for part of the day but shade the rest of the time.
Since azaleas have many feeding roots close to the surface, mulching is preferable to cultivation for keeping down weeds. Some azaleas will not tolerate extremes of cold and others will resent prolonged summer hear, particularly in areas where there is no dependable period of winter chilling, for all azaleas require some winter rest.
Hardy azaleas may be raised from seeds sown in pots or shallow flats. Sow them in February, March, or April in sandy, peaty soil, and place them in a slightly heated greenhouse or cold frame. To avoid damping off, try to sow the seeds in sphagnum moss. Fill the flats or pots with good soil and cover it with a1/2 inch layer of moss which has been rubbed through a ¼ inch mesh or sieve.
For cuttings, choose half-ripe or semiwoody shoots of the current year’s growth. Make these 2 or 3 inches long and take them off with a very thin heel or piece of the old branch during July. Place in a greenhouse in a mixture of sand and peat moss. Keep the frame closed for 3 to 4 weeks to encourage the cuttings to form roots, watering them after insertion and keeping them moist by daily spraying if necessary. You may also increase your stock by layering the lower branches in the summer.