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My Blog
My Blog
Blog
Cold Tolerance
| Posted on June 3, 2014 at 3:01 PM |
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One
big difference between heat stress and cold stress is cold stress can have an
impact on warm season turfs AND cool season turfs. Whereas heat really only affects cool season
turfs. Warm season turfs usually thrive
in warm weather. As logic might dictate,
cool season grasses are a little more tolerant of cold temperatures than warm
season grasses.
As
I’ve said many times in this blog, you got to select the species that is best
adapted for the region you are growing the grass. That is not only the turfgrass adaptation
zones (See my blog post on: “Turfgrass Adaptation”), but it also means the
immediate environment…your yard…your playing field. Is there poor drainage? Is there lots of shade? Is there only direct sunlight? What is the annual or seasonal rainfall? What is the use of the stand or area – high
use or low use? You have to look at all
sorts of issues.
I
will list below the cool season turfgrasses that are most tolerant to
the least tolerant of cold stress:
Rough
Bluegrass Creeping
Bentgrass Kentucky
Bluegrass Annual
Bluegrass Tall
Fescue Perennial
Ryegrass Annual
Ryegrass
The
warm season turfgrasses most tolerant to least tolerant of cold
are:
Zoysiagrass Buffalograss Bermudagrass Bahiagrass Centipedegrass
Carpetgrass Saint
Augustinegrass
As
I mentioned earlier, drainage is important.
Drainage is even more important in the case of cold tolerance. Okay; it is bad to have your turf submerged
for long periods of time. Now, imagine
your turf not only submerged but that water also freezes. And, it is a nice long, deep freeze. Not good.
Keeping turf excessively wet or frozen is a primary reason for cold weather
kill.
You
need to ensure not only surface drainage but also subsurface drainage. Both of these considerations are directly
linked to the “type” of soil you have.
What percentages of sand, silt and clay do you have? Sand is porous; clay is not very porous. What this means is you may have to do some
civil engineering on your property. You
may need to change grades, install drains (french drain, perimeter drain, filter
drain, collector drain, interceptor drain, fin drain, weeping tile, blind
drain, rubble drain, rock drain); that sort of thing. That usually involves digging, laying of sand
or gravel; maybe even some landscape fabric and installing some sort of pipes
and/or grates/basins. This is not an
inexpensive endeavor. And, do us all a
favor, if you do this yourself; call Miss Utility before you even think about
touching a shovel.
Judicious
use of nitrogen fertilizers also applies here.
I’ve written about getting a soil test to find out your requirements,
seasonal or monthly applications, etc.
In the past, my discussions about nitrogen fertilizers have been
regarding its affect on the environment.
Well, in this case, excessive late season applications of nitrogen can
increase the lusciousness of the turf. That’s
very nice, but it makes your turf more vulnerable to disease. And, if the turf is too
succulent, it will be more susceptible to low temperature stress as well.
Also,
with regard to fertilizer, maintaining adequate phosphorous and potassium
levels is important. Potassium is
especially critical to ensure cold weather tolerance. Some studies have shown that the balance or
ratio between NP & K is very important.
Cool season grasses show good cold hardiness if the N to K ratio is about 2:1 or
3:1. Warm season grasses should be
fertilized in late fall with something like a 4-1-6 NPK ratio for good cold weather
tolerance.
Finally,
more topics I’ve already laid out for you – mowing high and maintaining a low
level of thatch also help with cold weather hardiness. Mowing high increases photosynthesis capability and helps grow deep roots. While reducing thatch helps the soil surface dry out better and you won't have that moist layer remaining cold and have that layer freeze. Next,
I will get into shade tolerance. This
also goes back to my earlier topic where I discussed “turf or trees” in my
“Heat Tolerance” blog post.
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