Feast or famine? That’s a real problem for many house plants and others confined to small areas. Research has shown that plants do much better when their nutrient supplies don’t fluctuate. Unfortunately, when using regular garden fertilizer, the nutrient level is high immediately after application, but can greatly diminish before fertilizer is applied again.
In this article we’ll talk about controlled release fertilizers that provide a continuous supply of nutrients.
Whenever we talk about fertilizer, we usually mention that most plants need several periodic applications throughout the year. Soils have a limited capacity to retain nutrients. Those needed by plants for healthy growth must be replaced regularly. This method of applying fertilizer at periodic intervals is sound and accepted practice. But it does require a lot of time and work.
Controlled release fertilizers have been used by commercial growers for many years. They are liquid fertilizer concentrated in to granules, and surrounded by multiple layers of polymeric plastic resin. This covering controls the release of the fertilizers over a long period of time. When these granules are placed in or on top of the soil, water from irrigation or rain penetrates the plastic shell and dissolves the nutrient care. The granules then become tiny reservoirs of liquid plant food, and these automatically add regular amounts of nutrients to the soil.
Various formulations of controlled released fertilizers are available. Each one is designed to release nutrients for a specific period of time. Some release their elements within two or three months. Others supply nutrients for four to five months.
A single application of a controlled release fertilizer to flower pots or small beds should be enough to keep the plants at the optimum fertility level throughout a normal growing season. Over very long periods, it may be necessary to make additional applications to keep the fertility level constant.
These fertilizers have other advantages. They can be applied anytime of the year. They’re moisture dependent, rather than temperature dependent. With traditional fertilizer, nutrient uptake is slowed or stopped altogether, if the soil temperature drops too low. Controlled release fertilizer stop releasing nutrients only when the soil dries out. After irrigation or rain, they continue supplying their elements to the soil.
With new plantings, controlled release fertilizers can be mixed into the soil. For established plants, surface application is most effective if the granules are tilled in lightly about a half-an-inch to an inch. Be careful not to damage plant roots when tilling. If the fertilizer is applied to the soil surface, and cannot be tilled in, you need to wet the granules frequently and thoroughly to insure release of their nutrients.
Generally speaking, you need to use less of this kind of fertilizer if your plants are infrequently watered, have poor drainage, contain high salt levels, or grow in areas exposed to low light.
For more information about controlled release fertilizers, check with your garden center operator or contact the Gulf County Extension Service @ 639-3200 or visit our website: http://gulf.ifas.ufl.edu or www.http://edis.ifas.ufl.edu and see Publication SL 266 or ENH 1189