The answer to this question depends on your location and your goal in establishing the turf area as well as other factors such as the availability of irrigation on the site. These are all cool-season grasses (see “Do I need a cool-season or a warm-season grass” in this series). I will assume that you are in the central or northern part of the United States which is where cool-season grasses are best adapted.

Each of these species has its strengths and weaknesses and there is not one right answer for all locations. The answer may also be a mixture of these grasses depending on the conditions on the site. Let’s begin by considering the characteristics of each species.

Kentucky bluegrass has many advantages over the others. It provides a high-quality turf with excellent green color and density. It has an extensive rhizome system (underground stems) that allow it to spread quickly and fill in damaged areas. The rhizome system also provides tolerance of extended drought conditions. Kentucky bluegrass can go into dormancy for months to avoid drought and come back quickly from the rhizomes, which are protected underground, when water is available. It has great cold tolerance and has an extensive range from the central US to well into northern Canada and Alaska. It cannot tolerate excessively low mowing heights, although it will provide good density down as far as 1.5 in. It performs best in lawns at a height of from 2 to 3.5 in. In most lawn situations 3 inches would be the preferred mowing height, particularly in stressful conditions.

It also has some weaknesses. While it can tolerate long droughts because of the rhizomes, to keep it green and lush requires a lot of water and there may be better choices for regions where rainfall is low and where irrigation is limited or not available. It germinates slowly and takes a long time to become established. While ryegrasses will emerge in three days, Kentucky bluegrass may require 7 to 14 days, particularly in the spring. Probably its biggest disadvantage is its lack of shade tolerance. For this reason, it is often mixed with other grasses that provide better shade adaptation.

Tall fescue has gone through many changes in the last 30 years through breeding and selection. Traditionally, tall fescue was considered to be a coarse textured grass with turf quality that was inferior to Kentucky bluegrass. The older cultivars also grew faster than bluegrass and were more of a weed in a bluegrass stand. The newer turf-type tall fescues are finer in texture and are capable of forming a dense attractive stand that is much closer to Kentucky bluegrass in appearance. If you are going to use tall fescue for a quality turf area, it is very important that you get the improved turf-types. The old varieties are still on the market and they have a place in the forage industry for grazing and for roadside turf, but you will be greatly disappointed if you buy them for your lawn. The turf-types are more expensive and if you see tall fescue at a discount price, you are probably looking at the old varieties. They are often offered side by side with the improved types on the shelf at discount centers.

Tall fescue has some advantages over Kentucky bluegrass. It is more shade tolerant. It has a deeper root system and will remain greener going into a drought when irrigation is not available. It germinates and becomes established faster than bluegrass. It is more tolerant of high temperatures and is often found further into the transition zone than bluegrass. It is common to find it in Washington DC and even in southern Oklahoma and Northern Texas. These are areas where Kentucky bluegrass is rarely used because of its lack of tolerance of heat and drought. Tall fescue has better wear tolerance than bluegrass and is often used on sports fields and grass parking areas where wear and tear are a particular problem.

It also has some disadvantages. Tall fescue is subject to winter damage, particularly in the seedling stage before full maturity. We generally do not recommend it much further north than the northern counties of Nebraska and Iowa. In recent years, I have seen more of it in Minnesota and Wisconsin, but it is risky and can winter kill in harsh winters in those northern locations. It is a bunch grass, meaning that it generally lacks stolons and rhizomes and is not good at recovery from damage. This means that you may have to do some annual overseeding in damaged areas that would normally recover by themselves in a Kentucky bluegrass stand. It has an unusually large seed. That means that there are less seeds per pound. Add that to the fact that it is a bunch grass and the seeding rate for tall fescue is much higher than for Kentucky bluegrass. Where 1 lb./1000 sq. ft. is enough for bluegrass, it may take 6 to 8 lbs./1000 sq. ft. of tall fescue to provide a satisfactory dense stand. On a large area, that can be a significant increase in the overall cost of the project. Tall fescue is also somewhat susceptible to a fungal disease called “Brown Patch” and this has limited its use in the southeastern part of the transition zone around Washington DC and Virginia where it is often wet and hot in the summer. In the southern part of the transition zone, it is often a choice of tall fescue, or warm-season grasses like bermudagrass and zoysia. While tall fescue will stay green most of the winter, it will take far more water to maintain it than the warm-season grasses for the entire year.

If you plan to use tall fescue in the northern region, be sure to seed earlier than you would Kentucky bluegrass. The seedlings of tall fescue are quite susceptible to winter kill. Try to get the area seeded by early September. If you are using Kentucky bluegrass, seeding can take place well into October. The Kentucky bluegrass seedlings are much more tolerant of cold.

I referred to tall fescue as a bunch grass and it generally is. There are cultivars, however, with short rhizomes. These types have some advantages over the true bunch types, but the rhizome system is never as extensive as that of Kentucky bluegrass and even the best of these rhizomatous types will not recover from damage like bluegrass and may need some annual reseeding.

Mixing turf-type tall fescues with a small amount of Kentucky bluegrass has become more popular in recent years. The bluegrass helps in the recovery from damage and adds some density to the stand. If you use too much Kentucky bluegrass, however, you run the risk of segregation of the two species that reduces the quality of the turf. Generally, the Kentucky bluegrass should not exceed 10 to 20% by weight of the seed mixture.

There are two distinct types of ryegrass used in the industry. They are annual ryegrass (Lolium multiflorum) which is sometimes sold as Italian ryegrass and perennial ryegrass (Lolium perenne). As the names would indicate, annual ryegrass is an annual that generally completes its life cycle in a 12-month time period and dies, while perennial ryegrass is perennial and comes back year after year. In most situations, you do not want to seed a grass that is going to die in 12 months and annual ryegrass should be avoided. If you go to a big box store, or even a garden center you will be surprised to find that much of the seed for lawns on the shelf is annual ryegrass. Annual ryegrass is very inexpensive and it is there for the discount shopper who wants to save a few dollars. Do not fall into that trap, stay away from the annual ryegrass. (See “How to read a seed label” in this series). The only time I recommend annual ryegrass is when you want a temporary stand that you plan to kill and reseed. This may be the case when a home site is finished in the spring and you want to wait until late summer to seed with high quality lawn seed. In that case, annual rye will come up quickly and hold the slopes from erosion but be sure to kill all the annual rye before you seed the area in the late summer. Annual rye is also useful in the establishment of low-maintenance areas like roadsides and has a place in roadside grass mixtures.

The ryegrasses are known for their rapid establishment. They will come up in 3 days, whereas Kentucky bluegrass can take much longer to emerge. The perennial rye has good wear tolerance and may prove useful in sports field mixes for areas that get a lot of wear.

Their disadvantages are that they are bunch grasses that lack both rhizomes and stolons. They will generally form clumps that stand out in the turf and disrupt its uniformity. Depending on the cultivar, they can grow faster than Kentucky bluegrass which also affects the uniformity or the stand.

Like tall fescue, perennial ryegrass has undergone a lot of improvements in the last 30 years. The old cultivars grow rapidly and have tough leaves that are hard to mow cleanly. The new types are much closer to the growth rate and quality of Kentucky bluegrass and because of their rapid germination, make a good nurse grass to put with Kentucky bluegrass to improve the speed of establishment. Even the best of the newer perennial ryegrass cultivars is not a substitute for Kentucky bluegrass and should not be used as a stand-alone grass.

The old cultivars of perennial ryegrass are still available on the market. They are much less expensive than the improved turf-type cultivars and they may be side-by-side on the shelf with the improved types. Never buy the discount seed. The old cultivars are still used for grazing and roadside turf and they will remain on the market but they should not be used in a quality turf area.

The term fine fescue does not refer to a single grass species, but to a group of grasses in the genus Festuca that are known for their very fine leaf texture. They include Creeping Red Fescue (Festuca rubra), Chewings Fescue (Festuca rubra ssp. commutata), Hard Fescue (Festuca trachyphylla), and Sheep Fescue (Festuca ovina). Of the four grasses, only creeping red fescue has short rhizomes. The others are bunch grasses. They are known primarily for their adaptation to shade. They are much better than Kentucky bluegrass at tolerating shade and they are generally included in “shade mixes” with Kentucky bluegrass for turf areas with too much shade for Kentucky bluegrass to survive. They are usually not used as a stand-alone species with the exception of cool and wet environments in the northeastern US and eastern Canada.

The fine fescues originated in northern Europe and are widely used through Scotland and the Nordic countries. They are more tolerant of low mowing heights than Kentucky bluegrass and are often found on golf course fairways and even greens in that part of the world. While they are occasionally used on US golf courses, we generally use creeping bentgrass in the US as golf turf for low mowing heights.

They thrive in cool and wet climates but are less well adapted to the hot and dry conditions of the southern planes. They are generally not used much west or south of Lincoln, NB. They are not well adapted to Kansas City and south. In that region, tall fescue is more likely to be used as a shade adapted species.

As you can see, each of the grasses that we have discussed have specific environments that they are best adapted to. Turf areas often are made up of many different microclimates that include full sun, shade, and wet and dry areas. The best seed mix for areas like that will often contain several species, including Kentucky bluegrass, perennial ryegrass and one or more fine fescues. These mixes may also contain a blend of several cultivars of the species. There may be 2 or 3 different cultivars of each grass. These mixes are very good for areas with a variety of conditions such as are found on a college campus, where you will find full sun, shade and many areas with varying degrees of traffic. We often refer to these as “shotgun mixes”. Using a seed mixture like this allows the grass to adapt to the varying conditions. In full sun, Kentucky bluegrass predominates, in shade the fine fescues will win and in high traffic areas perennial rye or tall fescue will predominate.

The right mixture of seed will vary greatly from region to region. For that reason, it is very important that you purchase your seed from reliable, knowledgeable seed dealers who know the characteristics of each grass and cultivar and tailor them specifically to your region.

For those of you who are in very dry regions such as western Montana and Wyoming or perhaps you live in the very dry cold region of Canada east of the Rocky Mountains and lack sufficient water for irrigation to keep grasses like Kentucky bluegrass green there are a few other alternatives that will at least give you a ground cover. They include species like Fairway Crested Wheatgrass, Western Wheatgrass, Tufted Hairgrass, and Canada bluegrass. These cool-season grasses are very cold tolerant and can tolerate dryer conditions better than the common turfgrasses. They provide a moderate to poor quality turf but are better than bare soil or rock on a lawn. These will not be on the shelf of most garden stores. If they are the answer for your location, you will need to contact a seed wholesaler in your area to see if they can be ordered. If you have water for irrigation, go with Kentucky bluegrass.

Nick Christians, University Professor of Horticulture, Emeritus, Iowa State University

books: http://www.amazon.com/Nick-Edward-Christians/e/B001H6SB7A/ref=ntt_dp_epwbk_0

turf blog: http://www.iaturf.blogspot.com/

Fundamentals of Turfgrass Mgt. 5^th ed http://www.wiley.com/WileyCDA/WileyTitle/productCd-1119204631.html

Web site: https://www.hort.iastate.edu/directory/nick-christians/

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