Tuesday, October 9, 2012

Beware: Fertilizers Can Burn Plants

 If you water plants with ocean water, the salts in that water would eventually accumulate to a level that is toxic to the plant -- assuming a good rain doesn’t come each night to leach out these salts. Whether its ocean water, manure, or fertilizer, each contains salts that can accumulate to a toxic level. Salts are not just sodium and chloride found in ordinary table salt. The nitrates, phosphates, sulfate, etc., found in fertilizer and manures are also referred to as salts.

As an example, one cup of calcium nitrate fertilizer may be recommended for a large tree and one tablespoon for a small shrub.  Do not think that if one cup or one tablespoon is good, that two are better.  No matter how good a fertilizer is, too much, can burn and even kill a plant.

When plants are over fertilized, in approximately one to two weeks the tips and edges of the leaves will begin to turn brown.  With a slight overdose, tip burn may be all that occurs. A larger overdose will cause many or all of the leaves to turn brown and drop off.   Eventually, as the excess fertilizer is leached out (diluted and carried below the root zone), the plant will put forth new roots and new leaves.
Handle fertilizers with care.  Used properly, they will nourish plants; overdosing can cause injury.