Summer Season Care for Rhododendron
Reprinted from the ARS Quarterly Bulletin, Vol. 2, No. 2, 1948, "Rhododendron Culture"
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 wind burn and sun scald, 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 growth 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 seed pods are allowed to develop. The stem 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.