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Rhododendron Culture

Care Of Rhododendrons

There is nothing complicated concerning the cultural requirements of rhododendrons, providing a little care has been taken in choosing the proper location and planting of this noble shrub. A few simple rules easily learned and remembered, should be sufficient for any one to successfully grow and enjoy these plants wherever climatic conditions are favorable.

Protection of Roots

Rhododendrons produce many of their fibrous roots very close to the surface of the soil and therefore resent any active cultivation in their root area, such as hoeing or spading. Any weeds that may appear from time to time should be pulled when small. A two or three inch mulch of peat moss or leaf mold, which may be found under conifers or oaks, applied once a year, preferably in the fall, is highly important. It serves the threefold purpose of providing winter protection, keeping the upper root system moist during hot weather, and adding humus to the soil.


If this mulching program is carried out year after year, very little fertilizing of any kind will be required to keep the plants in excellent condition. It will also serve to maintain the proper soil acidity needed by nearly all rhododendrons. If the plants appear to need a little extra vigor, or if more rapid development is desired, a bucketful of well rotted barnyard fertilizer may be mixed with or applied on top of the mulch. Better still, one of the commercial fertilizers prepared especially for acid loving plants can be readily obtained at seed stores and applied sparingly according to manufacturer's directions. This may be used any time from early spring to June first.


As blooming season passes and new growth appears, watering becomes very important, especially during dry windy weather or when the mulch at the base of the plant is exposed to the sun's rays. A thorough watering of the mulch and root system once or twice a week, depending on location and soil texture, should be adequate. In hot weather supplement this daily with a light overhead sprinkling, preferably in late afternoon or evening. These precautions will eliminate windburn and sunscald, which may occur on the old foliage as well as on the new growth, due to excessive transpiration. Maintaining a moist condition, not soggy, at the roots during the growing season will ensure sturdy new shoots upon which are produced the bloom buds for the ensuing year.
Avoid using too forceful a spray when the new shoots are tender, as they are easily broken at this stage of growth. This watering program should gradually taper off when flower buds have set and the weather becomes cooler. Too much watering in autumn is apt to induce additional growth and prevent the gradual hardening of the current year's growth, which is nature's preparation for the winter season.

Removal of Old Blooms

Removal of all old blooms a short time after blooming is highly important as much of the plant's vitality is used in producing seed if seedpods are allowed to develop. The stern of the old flower truss becomes quite brittle and snaps off easily with thumb and forefinger. Removal may also be accomplished with sharp shears. Care must be exercised in either case so as not to injure the new growth buds or shoots at the base of the flower stem.
A few varieties may require disbudding if maximum flower development is desired. The need for this is apparent whenever the flower buds are too tightly packed on a compact growing plant to allow development of well-rounded trusses.


Pruning is required only to remove an occasional dead branch or to shape the plant to fit its surroundings. Certain varieties of stringy habit of growth may be induced to branch and grow more symmetrical if judicious pruning is done. When pruning is deemed essential, remove only such growth as seems necessary, taking care to Cut back to a rosette of leaves where dormant buds appear.