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Apply balanced fertilizer for best general gardens
MISSISSIPPI STATE -- Mississippi State University experts say applying fertilizer to plants should be neither random nor intimidating, and offer homeowners a few recommendations on how to take the guesswork out of the job.
Norman Winter, horticulturist with MSU's Extension Service, said knowing when and what kind of fertilizer to apply is not that difficult. The first step is to get a soil test.
"With a soil test, you supply information on what you're going to grow, and it comes back with a recommendation on what nutrients are needed," Winter said. "Sometimes a soil test will indicate no fertilizer is needed or none of a particular type should be added."
Fertilizer is sold by content, with the series of three numbers indicating the amount of nitrogen, phosphorous and potassium included. For general use on varied beds, Winter recommended a slow-release fertilizer with minor nutrients such as 12-6-6, 12-12-12 or 8-8-8.
"These fertilizers are not too high in any one nutrient, and they're coated to allow some of the nutrients to enter the soil slowly," Winter said. "I think that in our Mississippi soils, most plants do benefit from the minor elements of sulfur, iron, magnesium and others."
Some blends promise to last for up to a year, but while they definitely perform longer, Winter said their usefulness is affected by such things as soil and air temperatures, and water.
For best results, Winter recommended a light application every four to six weeks during the growing season. For winter-blooming plants, this means fertilizer must be applied in the cold months, something many gardeners do not consider.
Container plantings are very popular, but need more frequent fertilizer application because daily watering -- needed to keep them thriving in the summer heat -- leaches out nutrients. Winter said controlled-release or diluted, water-soluble fertilizers work well for containers.
Each situation is different and gardeners should base their actions on the results of a soil test. Not only can too much fertilizer burn plants, it also can negatively impact the environment.
Larry Oldham, Extension soil specialist, urged homeowners to look at the big picture.
"Each of us is part of a larger watershed. Although one individual may not apply a lot of material, they are part of a much larger area that affects surface water," Oldham said. "Use good management when applying materials, and only apply the amount specified by a soil test."
Avoid spreading fertilizer on streets or sidewalks, as these materials will be washed directly into the surface water system. Excess nitrogen and phosphorous can cause overgrowth of algae and can harm fish and desirable plants in waterways.
Not wanting to keep an economy-size bag of fertilizer sitting around all year is not a valid reason to apply the whole bag. Oldham said dry fertilizers are stable and can be stored indefinitely in a dry place. Liquid fertilizers have more variables, but also have a long shelf life.