How exactly do I fertilize my lawn?
There are actually 3 parts to this answer. First, choose a quality
fertilizer, then apply the right amount (rate) and apply at the
right time of the season. Quality nitrogen fertilizers should contain
controlled-release nitrogen (see next question for more on this).
The amount or rate of nitrogen to apply is about one pound of actual
nitrogen per 1,000 square feet of lawn area (see question below
for more on this). Finally, some suggested times in the season for
northern Illinois would be early may, early September, and late
fall (about Halloween).
What is the best fertilizer to use?
There is no one perfect or absolute best fertilizer to purchase
for your lawn, but there are many good ones available. Nitrogen
is the most important nutrient; percent nitrogen is expressed as
the first number in the series of three on the fertilizer bag. What
kind of nitrogen in the product is the key information, as there
are fast-release and controlled-release nitrogen sources. To find
the answer, look in the guaranteed analysis section on the back
of the bag. Key terms to look for include controlled-release, slow-release,
slowly-available, or water-insoluble nitrogen. Some specific types
that may be listed include ureaform, sulfur-coated urea, polymer-coated
urea, and IBDU (isobutylidenediurea). Several organic nitrogen sources
Most quality lawn fertilizers offer a balance of fast and controlled
release sources to offer a fertilizer that will provide some quick
color (without a big surge of growth) and some long-lasting nitrogen.
I don't want to burn my grass with high percent
nitrogren fertilizer, so can I just use a 10-10-10 garen fertlizer?
The high percentage of nitrogen by itself is not a problem, assuming
the amount put down on the lawn is adjusted accordingly. The higher
the percent nitrogen, the less product is needed on the lawn to
supply the one pound per 1,000 square feet rate suggested. In addition,
if the material is controlled-release, the risk of burning the lawn
is low even though the percentage nitrogen in the product may be
||Fast release nitrogen fertilizers,
which may contain high levels of salt, can burn lawns
Balanced fertilizers, such as a 10-10-10, have a N:P:K ratio of
1:1:1. The reason these are not suggested for repeated use on lawns
is the amount of phosphorus applied, when supplying the one pound
of nitrogen per 1,000 square feet, becomes quite high. Excess phosphorus
may lead to potential runoff problems and more weeds in the lawn.
Also, many of the all-purpose balanced fertilizers have only fast-release
nitrogen as the nitrogen component, so the risk of burn may be higher.
Are organic fertilizers better than conventional
Whether a fertilizer is organic or synthetic, after applied to
the lawn it must convert to a form the plant can use. Once converted,
the plant does not know the difference as to the nitrogen source.
One of the advantages associated with organic sources is low chance
of burning grass. Some synthetic fast-release sources have high
salt levels that increase the chances of burning. On the other hand,
most synthetic controlled-release sources are very unlikely to burn
A drawback of many organic nitrogen sources is the percent nitrogen
is quite low, meaning it takes considerable material to be spread
over the lawn to give the proper rate of nitrogen. Some materials,
such as compost, are best used as a soil conditioner to improve
soil quality, rather than to supply nutrients.
Furthermore, most organic and some synthetic fertilizer sources
rely on soil microbes to break them down to release nitrogen, so
they do not work when soils are cold. So as you can see, there are
tradeoffs to consider when making these comparisons.
Are dry fertilizer products better than liquid?
To accurately answer this, you need to compare the guaranteed analysis
in each product, not just the form they are applied. There are both
fast and controlled release nitrogen sources for liquid and dry
(granular) application. So in some cases granular can be better,
but in other cases, the liquid material may be better than a granular
it is compared with.
How do I know how much fertilizer to apply?
As mentioned earlier, the suggested rate per application is about
one pound of actual nitrogen per 1,000 square feet of lawn. If fertilizers
were 100 percent nitrogen, which they are not, it would take a pound
of fertilizer to apply this rate. Divide 100 by the percent nitrogen
in the bag (first number expressed a whole number) to figure how
much is needed per 1,000 square feet. For example, a fertilizer
with 20 percent nitrogen would require 100/20 or 5 pounds of fertilizer
product per every 1,000 square feet of lawn.
||Too much nitrogen fertilizer
has damaged this lawn.
The next figure needed is the total area or square footage of the
lawn. Take your total lot size and subtract everything not in lawn
to determine this figure. An acre is 43,560 square feet, if you
know your lot expressed in a portion of an acre. Then subtract the
square footage of the house, driveway, gardens, patio, etc. The
other way to figure is just to measure dimensions of the lawn areas
and calculate as square feet.
Once you arrive at the square footage in lawn, divide this by 1,000.
Then multiply by the pounds of fertilizer needed per 1,000 square
feet figured above. This gives you the approximate pounds of fertilizer
needed to spread on your lawn.
Using the previous example of a 20 percent nitrogen fertilizer,
lets walk through this. Dividing 100 by 20 gives 5, meaning
5 pounds of fertilizer is needed to supply 1 pound of actual nitrogen
for every 1,000 square feet. If the lawn measures out to 12,000
square feet, dividing 12,000 by 1000 gives 12. Now take 5 times
12, which equals 60. This means it would take 60 pounds of fertilizer,
spread over the 12,000 square foot lawn, to supply a rate of 1 pound
of actual nitrogen per 1,000 square feet.
Finally, most fertilizer bags give a spreader setting guide, which
is usually calibrated to supply the 1 pound per 1,000 square feet
rate, to help homeowners apply the right amount. The product label
may tell you how much area the product will cover.
What about weed control and fertilizer products?
Weed and feed products are popular in that they provide fertilizer
and weed control in one product. Early fall is a good time for controlling
broadleaf weeds, such as dandelions, and fertilizing. Read and follow
all label directions.
Another fertilizer and herbicide product is the fertilizer and
crabgrass control products sold in spring. These contain fertilizer
and a preemergence herbicide for crabgrass control. Once again,
read and follow all label directions.
||The lawn on left is fertilized
adequately, the one on the right is not fertilized.