SLOW-RELEASE FERTILIZERS

GARDEN PATCH POINTERS
By Robert H. and Hoberley Schuler

SLOW-RELEASE FERTILIZERS

Q: I have used a slow-release fertilizer in my containers. Are there other uses of this fertilizer in my garden? Harry Fritts, Petaluma

A: Using a slow-release fertilizer is an easy way to provide fertilizers to all plants in the garden. Some of these products are available as an organic fertilizer. The nutrients in a slow-release are not readily available to the soil, but are often used on lawns, where they extend the period of greening and for pots; they are used to reduce the times required for fertilizing. Slow-release fertilizer saves re-fertilizing due to heavy rains and leaching of the nitrogen in the soil problems.

Soil that has a lot of nitrogen will cause the slow-release to react slower. Soil organisms convert ammonium to nitrate which is highly soluble and available to the plant.
The rate of release depends on the type of organic material available and the environment (heat). Organic, dried or fresh nitrogen that is available to the plant, such as fish fertilizers, seed meals are easily decomposed and available to the plant. The warmer the soil is, the faster it will decompose if moist conditions occur. Do not sprinkle the slow-release fertilizer on the top of the soil. Mix it into the soil as you plant. A solid ring of fertilizer at the top could girdle or burn the plant.

Slow release fertilizers for lawns can contain either synthetic (contains urea) or natural organic materials or both.

Depending on the manufacturer, the slow release coating of the bead of fertilizer can be different which will affect the rate of use.
Slow-release fertilizer in warm So. Calif. Area will release the nitrogen faster than areas of Northern Oregon or Washington.

The number on slow-release packaging designates the length of time for nitrogen release. Slow-release 3-4 equals months so does 14-14.

The pH of the soil does not affect the reduction of nitrogen.

Finally, slow-release fertilizers when properly placed is unlikely to move into streams and lakes or to leach into groundwater.

Robert H. Schuler, Master Gardener
rhschuler@frontier.com

GARDEN PATCH POINTERS
By Robert H. and Hoberley Schuler
Oregon State (OSU) Master Gardener; NGC & CGCI
Garden Study and Landscaping Design Master Consultants