Compare coverage and cost of fertilizers

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So many kinds of fertilizer, choices can be confusing. We recommend slow release organic products (based on manure or plant/animal by-products such as alfalfa meal, fish parts, etc.) applied twice per year. Buy the fertilizer right for your soil in the package size most economical for the amount of garden you'll fertilize. 

Buy fertilizer to supplement the soil. Don't buy different fertilizers for each kind of plant you grow.

If you have a soil test result from a lab such as your State Agricultural university (Michigan State, etc.) the results tell you the type of fertilizer best for your soil and "crop", such as 10-10-10 or 4-6-4.fertlzrMarineCui.jpg

Read the fertilizer label for #-#-#. At right, the package is a 10-7-7 organic product: 10% nitrogen, 7% phosphorus, 7% potassium. Sometimes you will have to read the fine print on a label to find this information:
nitrogen    10.0%
phosphorus  7.0%
potassium  7.0%

No soil test results?
Use 1-1-1 ratio fertilizers.

If you do not have a soil test, look for a balanced complete, 1-1-1 ratio fertilizer such as 5-5-5, 3-3-3, 10-10-10 or as close to equal amounts nitrogen-phosphorus-potassium as you can find, such as 4-3-3.

Our chart helps you figure how much to use, when.

You can use our fertilizer chart to look at some of the products we've shopped. It will help you figure price per pound of nitrogen and how much bed area the package will cover. To check other fertilizer products, download our Excel fertilizer chart. The top of our chart lists fertilizers we've checked. Type in your fertilizer products in the bottom rows to see how much ground each will cover, at what cost.




Figuring how much garden you have

Not sure how many square feet of garden you have? Use our bed sizing tool in the Mulch Calculator.

Products included on our chart

Please note that we've included some products which we use as well as some we shopped only out of curiosity. For instance, we do not use and do not recommend using chemical weed preventers or weed-preventers-plus-fertilizer but included some on the chart to compare cost.

Once you have selected a fertilizer and figured how much to use per square foot of garden, stick to that. (Most gardeners do not apply enough fertilizer because they are afraid of burning plants. If that describes you, use a slow release organic product, use this chart for amount, and stop worrying!)


Above: We aren't proud! We have as much trouble keeping numbers straight as any gardener. For instance: This 5-5-5 fertilizer contains 5% nitrogen, so this 40-pound bag contains 2 pounds of nitrogen. That's enough for the average 1,000 square foot perennial/tree/shrub area for one year. That is four borders 5 feet deep and 50 feet long. Once we burn our brains to figure that we write that information on the bag, such as "Smith, back beds, full season."


Go organic, or not?

Organic, slow release fertilizers tend to be more expensive per pound of nitrogen than conventional granular or powdered salt based fertilizers. Of the two, the salt-based fertilizers should be used more carefully, as too much can burn plants. In addition, conventional salt based fertilizers do not contain any carbon/organic matter although this is essential for soil health and even nutrient release. If you use conventional salt based fertilizers, we recommend that you satisfy the soil's need for carbon by adding a liberal amount of compost, too.