by Lis Friemoth
Fall is time to fertilize your lawn
It’s important to get your turf ready for next year
Fertilizing lawns is a topic of delight and debate for
many turfies. Whether you are into high maintenance or
low, fall is a time to seriously think about that last
bit of nutrition to add to the lawn.
While the fall season really signals the beginning of the
end for most plant growth, it’s the time to make sure plant
systems have enough stored and available nutrients to get
a good start in the spring. Your lawn will love you for
applying fertilizer in the fall.
Typically, turf uses lots of macro- and micronutritional
elements to maintain good health. Macronutrients are those
elements needed in large quantities for continuation of
normal, healthy plant system functioning. Micronutrients
are those needed in smaller quantities, but are by no means
less important for good health.
Both of these element divisions are obtained through various
sources — air, water, and soil. The three macronutrients
most important for turf are nitrogen, phosphorous and potassium.
Nitrogen (N) is highly used by most turf types (Kentucky
Bluegrass and perennial rye) planted in this area of the
country. It is necessary for active vegetative growth (the
leaf blades), improves the natural color, and when applied
appropriately, strengthens the plant system. Being an intensely
used element, it is often provided artificially one or
more times throughout the growing season.
But, it is available naturally through organic matter
within the soil structure and that availability can be
enhanced by leaving your clippings on the lawn to decompose
— this can add up to a good savings on fertilizer as it
provides roughly the equivalent of one pound of nitrogen
per 1,000 feet squared per year.
If your turf is healthy, thick and lush, monitor the density
of the clippings at the ground level and de-thatch or aerate
as necessary. These two processes increase the amount of
air and water exposure to the turf root system as well
as the soil structure. The clippings will decompose faster,
increasing the availability of nitrogen to the turf roots.
Once any form of nitrogen is converted to a usable ammonium
or nitrate form, it uptakes easily into the plant system.
But at the point where it is easily taken up, it will also
rapidly travel through the soil via water movement. Therefore,
at times of high soil moisture — rainy periods — the nitrogen
can move deeper than the root structure, making it unreachable
and therefore unusable.
One way to counteract that loss is to use a slow-release
formulation. These formulations rely on environmental conditions
to break down the nutrients, working slower to provide
fertility over a longer period of time — depending, of
course, on soil and environmental conditions. This formulation
works best for fall applications because it provides nutrients
that slowly break down into the soil and, if soil temperatures
are conducive, uptake into the root system, thus preparing
the plant system for healthy, early-spring blade growth.
A question often asked: Why not just apply a fast-release
formulation in the spring? The root uptake and subsequent
leaf growth differs for the different formulations. A slow-release
fertilizer applied in the fall will slowly bolster the
health of the root system, which will provide for a healthier,
lushly dense top growth throughout the next growing season.
A quick-release spring application does result in lush,
fast top growth, but it can weaken the plant structure,
often resulting in a system more susceptible to disease
pressures and summer stress.
Phosphorus (P) and Potassium (K) are the other two macronutrients
that turf loves. Often, these are naturally available within
the soils found in this part of the country (a big thank
you to the glaciers and underlying rock structures) and
neither move readily through the soil structure. That makes
frequent applications often unnecessary.
Phosphorus, in excessive quantities, can wash with water
flow and is highly regulated in some areas. Be sure to
check local and state regulations prior to application.
Both of these provide for root stimulation and plant health
throughout the year and are, again, important but often
available naturally at levels that do not warrant any additional
applications.
What about weed, feed products?
In my opinion, they are not the best for either thing
you are trying to accomplish. Feeding needs to occur when
it is beneficial to the growth cycle of the turfgrass.
Weeding needs to take place when the weeds are at their
most vulnerable. And guess what? These don’t often coincide.
Turf needs to be fed around the summer and fall holidays
(Memorial Day, Fourth of July, Labor Day and/or Halloween).
The amount of that feeding depends on the health of your
turf, soil test results, and the level of maintenance desired.
Unless you have a lawn chock full of broadleaf weeds —
and then you should really start over from scratch anyway
— it is unnecessary to cover your grass with herbicides
just because it’s easier to apply that way. Weeds ideally
should be spot treated for best control. That can be accomplished
through very satisfying hand pulling or spot chemical treatment
if you so choose. Save yourself some money and do these
two things when treatment will be the most successful.
What type of fertilizer?
Look for a formulation that is slow release with a higher
proportion of Nitrogen (N) to Phosphorus (P) and Potassium
(K).
How much
fertilizer?
Well, the only way to determine the actual level of availability
of these nutrients is to have a quality soil test done.
Typically, these are available through most university
soil labs and farm co-ops and should be done every two
to three years.
In general, no more than one pound of Nitrogen per 100
feet squared of lean surface should be applied at any one
time. Most recommendations are to concentrate applications
toward fall rather than spring to increase overall health
and vigor. Unless your lawn is extremely nutrient-deficient,
nitrogen application for a year should not exceed three
to four pounds per 1,000 square feet.
— Lis Friemoth is a horticulture diagnostician. Contact her at (262) 745-2904, P.O. Box 58, Springfield, WI 53176, visit online at www.thegardenhoe.com or e-mail her at gardenhoe@tds.net. Listen to Liz from 9 a.m. to 10 a.m. every third Saturday on WISN AM1130 radio. |
