Weekly Express-News Article
By Calvin R. Finch, PhD, SAWS Water Resources Director, and Horticulturist
Saturday, September 22, 2007
“Fall Lawn Activities”
Because of our wonderful rains and mild temperatures lawns are
generally in good shape. The autumn is a key time of the year
for activities that are important in keeping the lawn healthy
The first activity that is essential is to resist the urge to
try and keep the grass as lush as it was all summer. Autumn is
brown patch time. The fungus makes circles of killed grass beginning
in low spots or other areas that stay damp. The best preventive
tactic is to keep the lawn on the dry side. Reduce autumn watering
to every ten days if you irrigate every seven days normally. Never
water more than once a week in the fall if you want to prevent
If the weather does not cooperate and we receive excessive rain,
brown patch may develop despite your conservative irrigation practices.
In that case the fungicides Turfcide and Fung-Away seem to work
well at stopping the disease. Repair of the dead areas may not
occur until next spring.
Many lawn experts think the fall fertilization is the most important
application of the year. It isn’t the most important fertilization
because of its contribution to fall greenness and lushness, it
is important because it helps the lawn survive cold winter weather
and make a fast start in the spring.
In the autumn the days are getting shorter and the lawn is changing
its internal chemistry. Instead of using available nutrients for
growth, the grass is reorganizing its nutrients to prepare the
plants for cold weather and for a fast growth start next spring.
That is why some turf specialists feel that the fall fertilization
is the most important of the year. Apply about one pound of nitrogen
per 1,000 spare feet for efficient fall fertilization. That translates
to about seven pounds of the typical winterizer fertilizer with
a formula of 15-5-10 or 18-6-12. The bag will usually also tell
you the setting on your fertilizer spreader to achieve the one
pound target. It is usually the lowest or second lowest setting.
Every brand has a “winterizer” formula fertilizer.
The nitrogen is released faster in a “winterizer”
fertilizer than the slow release fertilizer that is used in the
spring (May 1). If you have left over slow release fertilizer
from the spring it is all right to use it up on the lawn. The
other option is to use it in your vegetable garden or for cool
weather annuals; October is the time to plant them.
The rains have contributed to attractive lawns this summer;
they have also encouraged weed growth. Crab grass, purslane, spurge,
and other summer weeds will decline as temperatures cool, but
a new crop of winter weeds will take their place. Bedstraw, dandelions,
annual bluegrass, thistle, rye grass, and rescue grass will be
germinating as soon as the first cool spell moves in. It is not
too late to prevent the germination for most winter annual weeds
by applying a pre-emergent herbicide. These herbicides, when applied
as required on the label, provide a barrier that prevents seed
germination. The barrier lasts two – four months depending
on the product. Two that work well are Amaze for grassy weeds
and Portrait for broadleaf weeds.
Do not use pre-emergent herbicides where you want wildflowers
to grow. The materials stop desirable seeds from germinating just
as well as they do weeds.
Every year I receive questions about the desirability of keeping
the lawn green all winter with rye grass. Golf courses do it,
and the grounds can be striking as a green oasis in a drab winter
landscape. Planting rye really only works on a Bermuda grass lawn.
St. Augustine and zoysia are too thick for effective rye culture
and they noticeably decline after just a few years of rye culture.
Planting winter rye is a kiss of death for buffalo grass. After
one year of winter rye culture you can expect the buffalo grass
to have extensive dead areas. Even Bermuda grass is stressed by
the winter lawn, but less significantly.
My advice is to use winter rye as an erosion control on a new
lawn area in the winter if sod for your permanent lawn is not
available, but otherwise concentrate on making the permanent lawn
healthy and attractive.