JARS v62n2 - Organic Rhododendrons Fertilizers

Organic Rhododendrons Fertilizers
Terry Richmond
Port Alberni, British Columbia

An excerpt from the Nanaimo Rhododendron Society newsletter, Vol. 17, No. 7, March 2008.

Organic materials that can be used to create an organic fertilizer contain between one and all three of the macro-nutrients (N-P-K) and many trace elements. The seed meals, soybean, cottonseed, canola, flaxseed, sunflower, neem, etc., generally have an N-P-K value of about 5-2-1 plus trace elements. Kelp meal is reported to contain every element presently known.
It should be noted that most chemical fertilizers and even some organic materials high in nitrogen, such as fresh manure, blood meal and vampire bat guano, will burn the roots of dwarf and small rhododendrons. The same is true for caustic fresh wood ash.

Organic/Natural Materials and Their Most Important (N-P-K) Nutrient

Nitrogen (N)
Canola meal (5.5-2-1)
Cotton seed (6-2-1)
Neem meal (5-1-2)
Alfalfa powder (2-0.5-2)
Fish meal (3-2-1)
Blood meal (12-0-0)
Bat guano (10-3-1)

Phosphorus (P)
Bone meal (2-12-0)
Shrimp meal (0-3-0)
Rock phosphate (0-30-0)

Potassium (K)
Kelp meal (1-0.5-3)
Green sand (0-0-3)
Langbeinite (0-0-18)

Secondary Elements

Calcium –(CA )
Dolomite lime 20-30%
Agricultural lime 32%
Gypsum 22%
Wood ash 9%
Bone meal 22%
Fish meal 6%

Dolomite lime 10%
Epsom salts 10%
Langbeinite 11%

Langbeinite 23%
Elemental sulphur 70-100%