Grass is Grass is Grass? Not Really
This time of year, when folks are considering an upgrade on their lawn, or looking to replace the Kentucky bluegrass that needs to be mowed twice a week, myriad questions come to mind. None are more important that what grass species and cultivars you select.
Before you rush out to the box stores to purchase a “sun” or “shade” mix, it’s worth reading this excerpt from my book, The Organic Lawn Care Manual. Here’s just a brief selection from the large chapter:
THE CATEGORIES — Lawn grasses are typically divided into three primary divisions based on geography: 1) cool-season for the northern portion of the nation; 2) warm-season grasses for the southern portion of the nation; and 3) transitional zone for areas in between. Grass is no different than the rest of plants in the world of horticulture; some like it hot and some don’t. Some can make it where it’s dry and some won’t. Since seasonal climate changes everywhere are significant, with the exception of a few sub-tropical areas of the deep South and West, most grasses will go through major changes in appearance, health and overall vitality thought the year. It’s unreasonable to expect a lawn to look great every day, or for a single lawn grass to be all things to all people.
“People want a miracle grass,” said Don Hijar, owner of the Pawnee Buttes Seed Inc. of Colorado. “I’ve been recommending grass varieties to people for more than 30 years and I see the same thing over and over and over again with people having unrealistic expectations about what their lawn should look like for 10 or 12 months a year. But there are no miracles out there, and people should know that before they go out shopping for grass.”
Cool season grasses — If you painted a swath across the top half of the country, you’d encompass most of the areas that are naturally conditioned for cool-season grasses. They thrive in temperatures from about 50 to 80 and may go dormant in periods of extended 90-degree heat of the summer, or cold of the winter. Their color typically changes to brown during summer dormancy, but only lighter green during winter dormancy. They usually break dormancy easily when more moderate conditions occur.
Some cool-season grasses are grown in the South where the property owners afford themselves regular irrigation. Tall fescues seem to be the most common. Cool-season grasses are often overseeded into warm-season grasses in winter by homeowners who don’t like the brown appearance of southern lawns in winter.
Another key component of cool-season grasses is combining of species. When purchasing pre-blended cool-season mixes, you’ll rarely find 100 percent of any one species. Kentucky bluegrass, perennial ryegrass and perennial fescues are typically sold in some combination based on certain site-specific needs. A “park” mix designed for high foot traffic will often have a high percentage of perennial ryegrass, since ryegrass stands up well to foot traffic. A “shade” mix will have higher percentages of fescues, which tolerate shade far better than bluegrass. These three species get along remarkably well since they’re all relatively similar in appearance. In fact, planting a “monoculture” of just one species is not recommended, since this makes the lawn more prone to disease and insect infestation.
“People out here in Colorado have been so conditioned by the marketing that they won’t stand for anything other than a pure bluegrass lawn,” said Hijar. “People in the Northeast and Northwest have got it right. Lawns out there contain a lot of different grass species and they’re healthier for it. The planet is better off, too.”
Some cool-season grasses have another leg up. Scientists inadvertently discovered naturally occurring fungi known as endophytes that combat pests and disease. These microscopic organisms have been successfully bred into fescues and ryegrasses for several years and scientists are reportedly getting close with bluegrasses as well. Though not everyone is sold on the value of endophytes (see page xx), they can be powerful tools in natural lawn care.
Warm-season — If you took that same paint brush from above and dragged it across the southern third of the nation — with plenty of dips and valleys to accommodate mountains and other microclimates — you’d cover the areas where warm-season grasses dominate. They love it when it’s hot, unless it’s also dreadfully dry. They usually go brown when it’s too cold, but will bounce right back when the weather warms.
Long dominated by two warm-season species, Bermudagrass and St. Augustine grass, the southern lawn care industry has opened its arms at least part way to five other grasses (see chart, page xx) that may all thrive on less maintenance, fertilizer and water than the Big II. To varying degrees, these other grasses — Bahia, zoysia, carpet, seashore and centipede — are gaining footholds and in the right situation, can all make excellent lawns. If your lawn care professional tells you otherwise, ask yourself how he or she makes money. By mowing and fertilizing? Probably. If less mowing and fertilizer is required, that may be bad for the lawn care company, but it’s great for you and the environment.
“The lawn-care companies hate it when we promote grasses that don’t require a lot of water and fertilizer,” said Greg Freyermuth, a sales associate and agronomist from Turf-Seed Inc. in Hubbard, Ore. “They’re afraid we’re going to put them out of business. The homeowner, though, ought to do what’s right.”
Warm-season grasses, with a few exceptions, generally are not mixed. Appearances and growth habits are often so different, the combinations don’t work; one usually outcompetes the other anyway. It is a good idea, though, to plant multiple varieties — known as cultivars or hybrids — of each grass within one lawn. Endophytes are not yet available in warm-season grasses.
Transition areas — Some states, you probably know them if you live there, defy the general categorization of warm-season and cool-season. States like Kentucky — which averages 87 degrees in July and 23 in January — can make it tough on either warm-season or cool-season grasses. Colorado can hit 40 below at high elevations and 120 above at low elevations. In those cases, you need to be sure to contact your local Cooperative Extension agent to determine the best grasses for your communities. When in doubt, it’s usually safe to go with a combination of fescues, or to rely on a couple of native grasses that can both stand extreme highs and lows. Buffalograss and little bluestem are both conditioned to take wide climate variances and, depending on your rainfall totals, may be good alternative grasses, especially if you don’t want to be a slave to your lawn.
THE CHOICES — One final word before I provide a rundown on different species of lawn grasses . . . many of these grasses have had entire books dedicated to their every nuance. In Seashore Paspalum, The Environmental Turfgrass, for example, Ronny Duncan tells us that seashore paspalum likes to be “spoon-fed” its nitrogen, with none at all in the heat of the summer. Space limitations make it impossible to get all those sorts of details into a book of this size.
If you’re planning to make a major lawn renovation or installation, I strongly encourage you to seek out all possible sources of information in the beginning. That will save you so much time and expense in the end.
Sidebar: Grass Definitions
Species vs. Cultivar — You may recall taxonomy from high school, which is the classification of all living things in descending level of detail from kingdom to phylum to class, and finally down to order, family and genus. As is true with both plants and animals, most things within the same genus have a lot in common, but still look quite different. Underneath genus is the classification of species; as it relates to grass, everything within a species appears quite similar, but not always identical. The species of Kentucky bluegrass looks visibly different from another grass such as the species Bermudagrass. For even more clarification, however, botanists refer to cultivars or hybrids. These are varieties within a species that have subtle differences from each other. ‘Zenith’ zoyziagrass is slightly more drought tolerant than ‘Meyer’ zoyziagrass, for example, but otherwise it’s difficult to tell them apart.
Studying cultivar differences can lead to far greater success in natural lawn care. If you insist on growing Kentucky bluegrass, a species that generally uses far more water and nitrogen than most other grass species, you can look for the most drought tolerant bluegrass cultivar, or a bluegrass than grows better on infertile soils. Seed companies will provide listings that make those distinctions.
“Cultivars make useful changes in grass behaviors, but not quantum changes,” said Don Hijar, the founder of Pawnee Buttes Seed Inc. of Colorado. “You’re not going to have a bluegrass behaving like a Bermudagrass, no matter what cultivar you buy.”
Common Names vs. Botanical Names — Where applicable, I will include both names of grass plants and other plants in this book. Folks from different regions often have different common names for grasses — in South Carolina they call St. Augustine grass “Charleston grass” and folks I met in Georgia had me scratching my head when they called perennial ryegrass “feathergrass” — but the botanical names are the same everywhere. Botanical, or Latin, names are listed italics.
Rhizomes vs. Stolons — All grasses have roots that anchor and nurture the plants. Some species are “clump-forming,” meaning their roots generally expand outwardly in a circle in the soil as the plant matures, but the plant stays put. Other species of grasses have the ability to wander, which allows them to send up new shoots and knit together with other plants nearby into what we commonly refer to as turf sod. The ability of a grass to move about the soil is made possible by the presence of root runners known as either rhizomes — below ground — or stolons, which grow above ground.
The most popular grass in the South combines both properties within the same species. Bermudagrass sends out stolons and rhizomes, which makes it highly aggressive. Common Bermudagrass, which has not been improved through breeding into new cultivars, is in fact quite weedy because it can easily escape from the lawn and into gardens and pathways. Never buy grass seed containing only common Bermudagrass; be sure your Bermudagrass selection is a named cultivar.
Bluegrass, similarly, spreads by rhizomes to create a full, lush carpet-like appearance. Landscape contractors love it because it forms such a nice, uniform sod that can be harvested and re-installed onto customers’ lawns. Until recent breeding breakthroughs, fescues were only clump-forming, which means they didn’t lend themselves well to sodding applications. A new hybrid known as Rhizomatous Tall Fescue, or ‘RTF,’ will have wide application and lead to even more breeding improvements in the years ahead.
Dormant vs. Evergreen — All grasses commonly used for turf have a built-in ability to enter a sleep state known as dormancy, which protects the plants from excess heat, cold or drought. Some grasses can, under general conditions, stay green year-round, which makes them evergreen. The latter classification is generally broken right along the line that defines warm-season and cool-season grasses. Warm-season grasses almost always turn brown during cool winter periods of below approximately 55 degrees. Some cool-season grasses like Kentucky bluegrass, perennial ryegrass and the fescues are green even in winter; the only time they’ll go dormant and turn brown is during extreme dry periods of summer. If your bluegrass lawn is straw-brown in winter, it may be dead.
In the South, homeowners can overcome the brown appearance of winter dormancy by overseeding cool-season varieties into their lawn (see page xx). Chapter 7 on watering covers more issues related to dormancy.
Wear vs. Leaf Texture — We’ve probably all been seduced at one time or another by the soft, fine blades of Kentucky bluegrass. That wonderful barefoot sensation is caused by a leaf texture that is perky, but not pointed, supple but not stout. I know I was shocked the first time I got off a plane in Florida and experienced St. Augustine underfoot; I doubt Whitman ever would have written “Fields of Grass” had he lived at my father’s winter home, where sandals are required for a comfortable walk on the lawn.
Oddly enough, though, leaf texture and lawn wear have nothing in common. Fine fescues and bluegrass hold up far better to foot traffic than either coarse St. Augustine or centipedegrass, another warm-season variety.
Blends vs. Mixtures — Almost all grass seed in garden centers is packaged as either a “mixture” or “blend.” Even though the words are occasionally used interchangeably, they often mean something quite different. A “mixture” contains more than one type of grass species — maybe carpetgrass and centipedegrass, or zoysia with tall fescue. The package label will indicates the percentage by weight of each type, along with a cultivar or hybrid name and the expected germination rate of the seed.
A “blend” contains only one type of grass, with multiple named cultivars of the same species. Seedland Inc. of Florida, for example, offers a “Royal” blend of ‘Princess 77’ and ‘Sultan,’ two hybrid Bermudagrasses. Each different variety has certain desirable traits and, together can improve the quality of your lawn.
When possible, it is best to go with mixtures to increase the genetic diversity of the lawn, which will generally increase its resiliency. Most grasses will mix well with various others, with the notable exceptions of Bermudagrasses and St. Augustine.
Breeding vs. Genetic Engineering — Since I talked about cultivars, above, this is as good a place as any in the book to touch on the sensitive subject of genetic engineering. Breeding, in horticulture and in this book, refers to plantsmen taking pollen from one plant and dabbing it on another in hopes of creating offspring that combine the traits of the two parent plants. In other words, human bumblebees are trying to get a leg up on Mother Nature by speeding up the process of natural selection. In breeding, only plants within the same species are involved; it’s impossible, in other words, to naturally breed a bluegrass plant with a Bermuda plant.
In genetic engineering, scientists will insert genetic material from unrelated species — of plants, animals, bacteria or soils — into parent plants. In lawn grasses, at least one major company is testing genetically altered lawn grasses that resist weed killers such as Roundup. That means lawn keepers could spray the weed killer, but the grass would live. It may sound like a great technological breakthrough, but folks like Don Hijar and thousands of others are outraged. Though this book is not the place for a full-blown argument about genetic engineering, the practice is not accepted as part of a natural lawn care program, or by nationally accepted organic standards. Consumers are urged to learn more about the process and to make their own informed decisions.