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Bras and Bluegrass: This One's for Gardeners

By Megan Gross, Horticulture/Natural Resource Agent, Colorado State University Cooperative Extension

Kentucky bluegrass is to the environmentalist what a Victoria’s Secret catalog is to the feminist. "It’s a water hog!" exclaims the environmentalist. "It’s hog wash!" exclaims the feminist. Both sides of opposition complain we consumers are so blinded by aesthetics, whether it be the lush green of a healthy turf or the lush blonde of a healthy woman, we ignore the inevitable negative impacts on our communities and family life.

You may be surprised to know the negative impacts of the bluegrass are not unlike those of the catalog. Both bluegrass and catalogs, for example, kill trees. Bluegrass is habitually over-watered, and, although the turf can take it for awhile, innocent bystanders, such as lodgepole and pinon pine, cannot. Regarding the catalogs: I think we all know how these mass mailings kill trees. Men driving and reading the mail at the same time often run their cars into otherwise healthy trees. End of story.

Despite opposer enthusiasm, both Kentucky bluegrass and Victoria’s Secret catalogs are here to stay. And so I write this column today in defense of the Kentucky bluegrass lawn. (Lets be honest; it’s far more interesting.) Its advantages are far underrated, and its disadvantages owe no blame to the plant itself, but to the plant tender.

Let me first dispel a rotten rumor: bluegrass is not a water hog. Oh, sure, if you want it to be green, well, that’s another story. When subject to extreme heat or drought, bluegrass casually slips into dormancy (it will green up again when conditions are more favorable). When subject to merely moderate heat (or drought) AND a poor root system, bluegrass will quickly revert to dormancy and perhaps die. The secret to water conservation in a bluegrass world, my friends, is #1 tolerance and #2 a deep, healthy root system. I recognize a brown lawn in August will never be tolerated, so lets focus on building a healthy root system.

A plant’s ability to extract water from deep within the soil profile is directly related to its drought tolerance. "Drought tolerant" varieties of Kentucky bluegrass are simply those that, under ideal conditions, develop deeper roots than the conventional varieties. Even your "drought tolerant" fine fescues are only so because of their ability to grow very deep roots. Plant these "environmentally friendly" grasses on hard clay soil, however, and they will be no less susceptible to drought than your ugliest Kentucky bluegrass. So there.

So why is your bluegrass lawn such a water hog? Chances are it was sodded over soil that was stripped of its top layer and then compacted by heavy equipment. It is quite likely the sod was lain on a medium no more plant friendly than the brick or stucco that encases your home. The roots probably penetrate no more than three inches of the soil profile, because neither water nor oxygen can be found much deeper. The insidious plant is probably then subject to heavy fertilizer in the spring and summer, and a heap of "winterizing fertilizer" in the fall. F.Y.I., Dear Readers, "winterizing fertilizer" is the biggest rip in town, and heavy spring fertility not only depletes roots, but encourages disease and insect problems.

So, here’s what you do:

  • Have a soil test.
  • Go in with your neighbors and rent a core aerifier (the one that pulls the plugs). This will relieve some of that compaction, thereby encouraging more root growth. Do it once in the spring and once in the fall.
  • Fertilize in the fall with a quick-release nitrogen fertilizer after your last mowing but before the grass turns brown. Kentucky bluegrass uses between four and six pounds of nitrogen per thousand square feet in a year. 75% of this nitrogen should be put down in the fall, after your last mowing. Fertilizer at this time goes into root production, not top growth. This has proven to lead to earlier spring green-up and healthier turf (more drought tolerant). Do not fertilize more than pound/1000 square feet of nitrogen fertilizer in the spring. It will deplete roots reserves and create an unhealthy lawn.

I know this is a lot to digest. Please call your local extension office if you have any questions. We must work together to make our Kentucky bluegrass lawns the healthiest and least consumptive they can be. Besides, we do need a comfortable place to sit while we thumb through our Victoria’s Secret catalogs.

Photograph courtesy of Judy Sedbrook.

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Date last revised: 01/05/2010