Environmentally Friendly Fertilizers

Synthetic fertilizers may be fast-acting but they come with a price

So it’s finally cool for mainstream America to go green. Organic, environmentally friendly products are showing up everywhere, from what we put in our gardens to the clothes we wear on our back.

Some organic choices require very little thought, such as selecting organic carrots for example. We know they were grown without harmful chemicals. But what does the farmer or you as a gardener select to fertilize and grow food organically?

Admit it. Now that you’ve decided to grow green, you’re as confused as the next guy when it comes to actually knowing what fertilizer to buy. The list of questions builds as you stand in front of the organic gardening section, blankly staring at the increasing choices of bagged and bottled fertilizer.

Before you give up, unsure of what to make of it all, allow me to explain some of the differences between natural, organic fertilizers and synthetic (non-organic) choices, review a few fertilizer basics, and then offer some viable organic alternatives to non-organic products.

Organic vs. non-organic choices

All plants receive their nutrients in chemical form. They cannot distinguish between how the nutrient was derived, whether organic or non-organic for example.

When referring to plant nutrition, organic or natural generally refers to any fertilizer which is derived from plant, animal or mineral origin. It must have one or more essential nutrients for plant growth.

Non-organic fertilizers (also known as synthetic) are manufactured chemically. They are made to deliver nutrients rapidly, such as those that are water-soluble, or over time as a controlled release.

Although very effective for providing rapid or prolonged periods of feeding, these have a high salt index. The potential risk to plants and the soil food web is burning and dehydration with the leeching of unabsorbed chemicals into waterways.

Organic nutrients on the other hand, must first be broken down and digested by soil microorganisms which then release these nutrients in a form available to plants.

This process also produces humus, a vital ingredient to improving soil structure. As part of this structure, organically derived nutrients are very resistant to leeching and contain a very low salt index. The net result is nutrients that remain in the soil until utilized by plants and little risk of burning or dehydration, even in periods of extreme drought or over application.

Fertilizer Basics

Look at any fertilizer package and you’ll find three numbers prominently listed. These are the primary nutrients that are needed in the greatest quantity by the plants. These numbers represent the percentage of nitrogen, phosphorus and potassium found in each package.

Nitrogen is primarily responsible for vigorous growth and dark green color. Phosphorus plays a major role in the root development and flowering. Potassium is mainly responsible for disease resistance and the overall hardiness of the plant.

Based on what you are trying to achieve for your plant’s growing success will usually determine which fertilizer to buy. That decision is based on the numbers referred to above. When in doubt, a good choice is to select a balanced product, one with an equal percentage of all primary nutrients, such as 10-10-10. Another environmentally friendly fertilizing option is a slow release natural product, like Milorganite, which releases nutrients slowly to the plant (8-10 weeks) and adds organic matter to feed the soil.

Organic Alternatives

Synthetic fertilizers are usually listed simply by their numbers (like 10-10-10 above), since they are manufactured chemicals. Organic alternatives however are often listed primarily by what they actually are, such as blood or bone meal.

But somewhere on that package, you’ll find those all important three numbers which is the key to knowing what role that product will play in your garden. Here is a partial listing of the most commonly available organic fertilizers sorted by their role for providing nitrogen, phosphorus or potassium.

Nitrogen: Dried blood, blood meal, cottonseed meal, fish emulsion and seaweed extract

Phosphorus: Bone meal, rock phosphate

Potassium: greensand, sulfate of potash

In addition to the three primary nutrients listed above, there are 12 other elements considered essential for plant growth that are absorbed from the surrounding soil. Organic soil amendments are a readily available way to provide all of these elements as well.

I rely on these natural amendments to ensure I’m feeding the soil which in turn feeds the plants. I find that to be a safe, effective and environmentally responsible approach to gardening.


Joe Lamp'l is the Host and Executive Producer of the award winning PBS television series Growing A Greener World. Off camera, Joe dedicates his time to promoting sustainability through his popular books, Compost Confidential blog, podcast series, and nationally syndicated newspaper columns. Follow Joe on Twitter

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  1. Ray Jones says

    I garden in raised beds (8′ x 4′ x 12″). The soil consists of primarily leaf compost with some added garden soil and composted manure so the soil is relatively healthy.

    What amounts of blood meal, bone meal and greensand would you recommend annually?



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