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.
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.