Definition: Greensand is an organic fertilizer that contains the deposits of minerals that were once part of the ocean floor. Also called "glauconite," greensand has a bluish-green color. The NPK ratio for greensand is approximately 0-0-3. It is a good organic source of potash (important for overall plant health and disease resistance) and can also be applied at a rate of 50 to 100 pounds per 1000 square feet to improve clay soils.
Also Known As: Green sand, glauconite.
Alternate Spellings: green sand
Greensand is also a useful component of container garden soils and seed starting mixes.