University of Florida

Slow- vs. Controlled-release Fertilizers

You may have heard the terms "slow-release" or "controlled-release" used to describe fertilizers. But what do they really mean? From a consumer's standpoint, they're almost interchangeable, since both products release nutrients gradually. The differences are in how the products are made.

Controlled-release fertilizers are inorganic fertilizers that have been modified, usually with a coating, to release nutrients over a specific period of time. They often look like colored ball bearings. Slow-release fertilizers depend on other aspects of their formulation to release nutrients slowly, usually over a few weeks or a few months. They can be either synthetic or organic. An example of a synthetic slow-release fertilizer is sulfur-coated urea.

UF/IFAS Publications

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