Homemade Phosphorus for Flowers

Bone Meal

• Bone meal is made from finely ground animal bones that are usually steamed, since raw bone meal is slower to break down. It is the best organic source of readily available phosphorus, and remains in the soil for 6 to 12 months. Bone meal contains 10 to 12 percent phosphorus, a tiny bit of nitrogen and about 24 percent calcium. It's beneficial when transplanting and for use with early season flowers when the soil's microorganisms are too sluggish to release enough phosphorus.

Hard Rock Phosphate

• Hard rock phosphate is finely ground phosphate mined from various places, including Florida, Idaho and North Carolina. It contains 30 percent phosphorus, 48 percent calcium and small amounts of other micronutrients like iron. The rich amount of calcium makes this organic phosphorus source good for many alkaline soils, although the phosphorus becomes more available in acid soil. It's slow acting and remains in the soil for approximately 5 years.

Colloidal Rock Phosphate

• Colloidal, or soft, rock phosphate is a byproduct of mining hard rock phosphate. The claylike material is washed out from between layers of rock phosphate. It contains about 19 percent calcium and between 16 and 20 percent phosphorus, of which 2 percent is readily available, making it faster-acting than hard rock phosphate. It remains in the soil for 3 to 5 years.

Green Manure

• Green manures are plants that are grown solely for the purpose of turning them under to supply the soil with organic matter. All legumes, like peas, beans, clover, and vetch, contribute all three of the major nutrients: nitrogen, phosphorus and potassium. Low-growing clovers work well in a perennial flower garden as living mulch. Buckwheat is a non-leguminous, commonly grown green manure that scavenges phosphorus from insoluble soil particles.