Rhododendrons should be fed in the Early Spring, Late Spring, Early Summer and again in the Fall. (4) times is ideal with low concentrates of granular fertilizer. Here is the actual NPK *(Nitrogen, Phosphorous and Potassium) ratio. The pH level where a rhododendron will be most capable of utilizing the fertilizer is between 5.0 and 6.0., slightly Acidic. (Neutral pH is 7.0)
The basic theory is to feed them as often as convenient with as low dosages as possible. (hypothetically, this would be every 5 minutes with miniscule amounts). Realistically, (4) times per year is perfect!
Just give me the basics: Go to your local Garden Store and buy "Rhododendron, Camellia and Azalea and other Acid Loving plants" food. Sprinkle a small hand full around the perimeter of plant (drip-line). Water in well. Do this in the spring and again around July 1st. DONE!
More detailed fertilization program:
(Nitogen, Phosphorus, Potasium [NPK])
Early Spring Feed:
Nitrogen (N): 20%
Phosphate (P): 5%
Potash (K): 10%
Trace Elements of Sulphur (3%), Iron (1%) Magnesium Sulfate (1%)
Early Summer Feed:
Nitrogen (N): 10%
Phosphate (P): 20%
Potash (K): 10%
Trace Elements of Sulphur (3%), Iron (1%) Magnesium Sulfate (1%)
Fall Feed:
Nitrogen (N): 5%
Phosphate (P): 20%
Potash (K): 5%
Trace Elements of Sulphur (3%), Iron (1%) Magnesium Sulfate (1%)
Think of trying to grow roots as well as foliage. To do this, force the roots to "GO GET" nutrients (fertilizer). This way, roots will travel in search of food and moisture. Give them food then deprive them of food.
NOTE: The dryer the plant, the more intense the feed. The more wet the plant, the less intense the feed is. If you overfeed them and the plants are burning around the edges and/or look chloractic, water them very thoroughly to wash away the feed. This oscillating process builds healthy root systems which will insure the plants survival in hard droughts and bitter winters.
