Cool Season Grasses

Tate’s Tips

A Series of Reflections on growing grass for forage


Issue 5.


Cool Season Grasses

 There are many classifications of plants.

 There are annual plants and these are plants that usually grow for a single season or a single crop.  Annuals include tomatoes, potatoes and, in fact, most vegetables;  corn, wheat, beans and most other commodity crops and forages such as Oats, millet, Crimson clover, sudex, sudan grasses and turnips, canola  and other brassicas.

 There are a few biannual plants which have a two year life cycle.  The most notable of these from a production standpoint would be red clover, a very useful legume.   Another would be Canada thistle, a weed.

 Then there are longer lived plants which are known as perennials.  Their lifespan is determined to a large degree by the growing conditions and management they are exposed to.  These would include many of the common pasture and hay grasses such as Orchardgrass, Fescue, Bluegrass, Timothy, Switchgrass, Indiangrass, Bluestem,  Bermudagrass, Crabgrass and legumes such as White Clover, Ladino clover and several other clovers, Alflafa, Birdsfoot trefoil and lespedeza.

 Some plants like ryegrass have cultivars that are annual and others that are perennial.  Crabgrass can come back from the roots but it sets so many seed so quickly, that once you have a good stand it will stay with you for a long time.

 Of the plants named above, many were warm season plants and some were cool season plants.

 Corn is the ultimate warm season plant.  When it is so hot and sticky that you are uncomfortable; corn, given adequate moisture, grows so fast that the growth is almost visible.  In the late spring you can measure a day’s corn growth.  However any frost will damage corn terribly as it does not tolerate cold weather.

 On the other hand small grains like wheat and barley and rye and canola are cool season annuals that in our state are planted in the fall and they overwinter to flower and fruit in the spring.  They tolerate cool weather better than corn and in fact do not perform as well in summer heat.  There are western varieties that are grown in the northwest United States that are summer varieties.  Plants are amazing at their ability to adapt and perform in so many different environments.

 The focus of this article is intended to be on cool season perennial forages that are common to Virginia.  Within this category, what is common in the eastern coastal plain and what is common in the mountain west and southwest parts of the state may be very different.

 Let’s start simple.  Cool season grasses prefer the cool seasons of spring and fall.  Freezing weather will cause them to go dormant, but they overwinter well.  Hot dry weather will cause dormancy too and extreme heat and dry can be fatal to some cool season grasses.  Generally cool season grasses and mixtures should be planted in the early fall.  They can be planted in the spring but weed pressures and environmental factors are more inhibiting to a successful establishment.  Summer and winter plantings need extreme luck and management to survive.

 Oats is a cool season plant that has varieties that can be planted in the fall called winter oats, and also there are spring planted varieties called spring oats.  Spring Oats are not cold tolerant and will winter kill.  Both are annuals and both can be used as forage as silage or hay or harvested at maturity for grain and straw.  The spring oats would mature at a later date.  Once harvested they are essentially done.  Oats are sometimes used as a nurse cover crop for new seedings of perennial forages.  Now wasn’t that easy.

 Timothy  is a cool season perennial except in the eastern half of Virginia.  While it is excellent forage and makes good grazing or hay, it is not hardy enough to persist in the hot and dry part of the commonwealth.  The hay producers in eastern Virginia interseed timothy annually in their hay fields to provide it to the customers who prefer it.  A spring cutting can be made and then the timothy perishes due to heat and dry conditions.  Basically one could say it is the coolest of the cool season grasses with no tolerance for hot dry conditions.  It can be a perennial in the high mountains and in southwest Virginia.  See still easy.

 Bluegrass  is a cool season perennial that will persist under hay making conditions and will survive the stress of hot and dry.  It will not be productive during that time but it will survive.  It is a smaller finer forage that makes excellent forage but lesser tonnage than some other grasses.  Does not handle stress and close grazing so it does not survive well in continuous grazed pastures.

 Orchardgrass is a cool season perennial that is close to blue grass in hardiness.  It is a larger and more productive plant and has a deeper root base than bluegrass.  Recall that the more plant we have above ground the more root mass we have underground.  It produces excellent quality forage and under well managed hay programs I have observed stands of Alfalfa and Orchardgrass that were 18 years old.  It will persist in summer with moisture.  If temperatures are moderate and moisture is adequate it will produce multiple hay cuttings.  If these conditions are not met it will simply go dormant until favorable conditions return.  It also is excellent pasture forage but it must have rest.  Continuous grazing will kill Orchardgrass.  Extreme drought will also kill Orchardgrass but it will survive a typical Virginia summer.

(Please refer back to Issue 2, How does your Plant Grow? For a refresher on this concept.)

 Now having read the refresher and eaten a few cookies, this too is simple, Right ??

I should not reveal all this as we make good money for our scholarship fund renting no till drills to folks who plant Orchardgrass every year.

 Ryegrass is both an annual and a perennial depending upon the variety.  It is a vigorous and copious seed producer and if allowed to set seed will be a recurring annual.  Rye grass is an easy starter and a vigorous grower and produces high quality palatable forage suitable for pasture and for hay or silage.  It is useful for getting fast establishment on bare areas and is tolerant of a wide variety of growing conditions.  It also is not a heat tolerant plant in either annual or perennial variety.  It is the first grass to green up in the spring and the last to quit growing in the fall and I include it in my recommended mixes as it has the greatest chance at establishment.  As a cool season grass it is virtually dormant in most summers but will reemerge with cooler weather and rain. 

 Use ryegrass with caution if you adjoin a small grain production field.  Ryegrass is a serious weed in small grains and is invasive and difficult for grain producers to control.  I have no desire to be implicated in causes of gunplay between neighbors.

 Have you noticed a trend yet?

All of these grasses in most Virginia summers experience what is called summer slump.  The heat and dry conditions are just too much for them and they shut down until conditions improve.  Some more than others.   Everything is still simple so far except that we don’t have any summer grass yet.  We will get there later.  Refer to the chart below taken from Controlled Grazing of Virginia’s Pastures for a graphic representation of what we have discussed so far.

 Fescue is the most common and most abundant and hardiest and most productive of the cool season grasses.  Fescue stands up to hard grazing better than any of the other cool season grasses.   It will still have a summer slump because it is still a cool season grass.  But it will survive.  Fescue is a bit less palatable than some of the other grasses.  It still makes good forage and grazing but given a buffet of ice cream, pizza, hamburgers, and brussle sprouts, the brussle sprouts don’t have to worry about me bothering em.  Fescue is the forage equivalent of brussle sprouts.  Eat em cause they are good for you.  Yeah Mom, soon as I polish off this pizza.

 Animals select the most palatable plants first and go back for regrowth as soon as it appears.  They will graze around the tougher fescue until the ice cream is gone and then they will eat the brussle sprouts (fescue).  This natural animal tendency puts negative pressure on the Orchardgrass and positive selection pressure on the fescue.

 Fescue is a complicated grass as well.  It gets a good part of it’s hardiness from an organism called an endophyte.   The endophyte is a microscopic organism that lives in fescue and concentrates in the seed heads.  Rather than pay rent the endophyte benefits the fescue plant contributing to the plants hardiness. 

 The endophyte also has the side effect of some toxicity to animals.  In cattle it increases summer slump by restricting blood flow in the animal and creating over heating problems and thereby suppresses animal production and performance.  It can have reproductive repercussions as well in cattle.

 In horses the problem is in pregnant mares.  Pregnant mares exposed to the toxic endophyte with have a high percentage of foaling problems.  I will leave it to discuss with your equine practitioner for specifics. 

 Once the troublesome endophyte was discovered quite a few years ago, enterprising plant pathologists were successful in removing the endophyte and created;

  Endophyte Free Fescue  Seed is available for endophyte free fescue today and it eliminates the toxicity problems of fescue.  In fact it made fescue a more palatable plant and made it more like Orchardgrass.  The problem is that the endophyted free fescue is now no hardier than Orchardgrass.  For the good forage manager this is not too much of a problem as the fescue can be managed right along with the Orchardgrass.  For those who overgraze… just ran out of grass again.

 The newest option is a fescue which has been developed with a novel endophyte that gives the fescue its hardiness back and yet eliminates the toxicity of old Kentucky 31.  Only one seed company has this product and the seed is a bit expensive but it is a good product that works.  Over time native Kentucky 31 can infiltrate a stand of Endophyte friendly fescue and it is not discernibly different.

 My advice for mare owners is to keep pregnant mares off of fescue and cattle can be selected for fescue adaptability as some cattle are much more tolerant of it than others.  Interseeding of fescues with other grass and particularly legumes is of great benefit.  Pasture management is an integral part of managing the toxicity problems.  Clipping of seed heads reduces problems greatly as well.

 Matua  is a new variety of brome grass that seems to be relatively well adapted to Virginia.  It is a good and vigorous producer but needs management similar to Orchardgrass to maintain a good stand.

 We have yet to cover warm season grasses or legumes.  We will hit those in the next two topics.

 Some excellent reference reading links are below for those who want to learn at a more in depth level as well as the forage seasonality chart.

 The first two are basically the same.  One is a web page and the other is a PDF file.  I find the PDF file to be more useful. 

 The third link is to a list of publications by Dr. Chris Teutsch who is  Virginia’s current leading authority on forages.



 Chart taken from controlled Grazing of Virginia’s pastures

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