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Match fertilizer to plant

Thursday, April 23, 2015

Q. What is a good natural and organic fertilizer?

Gemma from Poland

A. There are tons to choose from. In general, fertilizers are either organic (coming from nature in some form or another) or inorganic (manufactured). Those within each category are very different from one another — in composition, amount of nutrients and other components.

Before choosing one, aim to understand what your plant or garden needs. Is fertilization necessary? Are you producing a fruit, vegetable, flower or shrub? Fertilizer needs for these types of plant are very different.

The macro nutrients needed by plants are nitrogen, phosphorus and potassium (N-P-K). These will be listed in this order on any package of fertilizer you purchase. The numbers (i.e. – 10-10-10), mean there is 10 percent nitrogen, 10 percent phosphorus (in the form of phosphate) and 10 percent potassium (in the form of potash) in the bag. The other 70 percent of “stuff” in the bag is filler material, organic matter or other components, depending on the type of fertilizer you choose.

Organic fertilizers available to homeowners range from manure to fish emulsion and even kelp these days. Garden centers stock lots of options to choose from. Many of these organic fertilizers have lower rates of nutrients than inorganic fertilizers, but can provide nutrients in a slow-release manner. They also offer a lot of organic matter, which can improve soil structure as well as water-holding capacity.

So what’s the best one? It depends on the needs of your plants or crop. Compost and manure tend to be the most widely used and offer a high amount of organic matter. Manure should be properly composted or incorporated into the soil. Kelp products tend to provide micronutrients rather than the macro nutrients. Fish powder and fish meal fertilizers are higher in macronutrients

Before using fertilizers, you should do a soil test. Find out how at: To learn more visit

Eric Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County. Call the office hotline at 330-533-5538 to submit your questions. Clinic hours are Mondays and Thursday from 9am-12pm, through October.