Understanding Those Bluegrasses

Published: October 10, 2014

The bluegrasses are a diverse group of turfgrasses that have hundreds of varieties on the market for various sub-species. All bluegrasses can be identified by a boat-shaped leaf tip and folded vernation. Among the species, variations in color, texture and growth habits exist. Some are yellow-green in color while others are dark blue-green. Some are coarser in leaf texture than others. Some will spread by stolons or rhizomes or not spread at all. In this article, we will discuss some of the more common bluegrasses seen in Missouri with a final focus on some of the more current Kentucky bluegrasses varieties.

Annual bluegrass

Annual bluegrass (Poa annua) is mostly considered a weed in many turfgrass settings. However, in some venues it is a component of the turfgrass sward; such as on putting greens, since it adapts well to close mowing. It is different from the other annual weeds we are used to. Annual bluegrass is a winter annual that emerges and matures vegetatively in the fall. It will flower, set seed and die in the spring if it is a true annual bio-type (Poa annua var. annua).

Some annual bluegrass bio-types behave as a perennial (Poa annua var. reptans) surviving throughout the year often developing seedheads throughout the year. Seadhead development is often troublesome and unsightly. Annual bluegrass can contaminate production seed fields and therefore contaminate some commercial seed products.

Some commercial types of improved perennial Poa annua are being developed for the golf course industry. Penn State currently has a breeding program for annual bluegrass. DLF-International Seeds is currently some annual bluegrass varieties – True Putt (golf industry) and World Cup (sports turf). We have not seen annual bluegrass being used in Missouri as a turfgrass of choice. It is still considered a weed in the gold course industry.

Kentucky bluegrass

Kentucky bluegrass (Poa pratensis) is a turfgrass species that was substantially a bigger part of home lawns in the 70s and 80s than it is right now. Its current foothold is still in athletic fields and golf courses. Yes, we still see Kentucky bluegrass being used in home lawns, but more so in a mixture with turf-type tall fescues. Hot, droughty summers of the past decade have transitioned many home lawns from a blend of bluegrasses to mixtures with other species. Kentucky bluegrass is not as deeply rooted as tall fescue and therefore has a tendency to go dormant faster than tall fescues.

Kentucky bluegrass is not a bunch-type grass like most tall fescues. It spreads by rhizomes providing an advantage over other turfgrass species to allow excellent recuperative capabilities. Many of the newer, improved varieties are being developed for better drought tolerance, disease resistance and low maintenance. Several varieties have shown resistance to several diseases – dollar spot, leaf spot and summer patch.

Some of the more recent Kentucky bluegrasses tested by NTEP from 2006 to 2010 are listed below. These selections were based on evaluations for quality, color, dollar spot, and leaf spot. Several selections from this listed were also rated well for summer patch, as noted (See Table 1).

Table 1. Kentucky Bluegrasses

*Summer patch resistance.

Rough bluegrass

Rough bluegrass (Poa trivialis) is mostly used in cool, humid regions under shade. It actually does better than Kentucky bluegrass in the shade. We see it in Missouri mostly due to establishment through contaminated seed. Patches of this finer leafed grass may be mistaken for Nimblewill. It does spread by stolons and is intolerant to dry conditions, reasoning for it browning out during Missouri summers. Due to its lack of tolerance to dry, hot weather; it is used as an over-seeding species in the southern states.

Most often this specie is referred to by a shortened version of its Latin name – Poa triv. There are several varieties commercially available – Bariviera, Colt, Laser, Racehorse, Proam, Sabre, Sabre II, Sun-Up and Winterlinks.

Texas bluegrass

Texas bluegrasses (Poa arachnifera) have proven to be well adapted to arid and semi-arid regions such as Texas. This grass species has had limited use due to its lesser quality than Kentucky bluegrass. It has been crossed with Kentucky bluegrass to create a hybrid that is heat tolerant with Kentucky bluegrass qualities. Several commercial varieties are available with some being introduced into seed mixtures at some of the box stores and local garden centers. These include – Bandera, Dura Blue, Longhorn, Reveille, Solar Green, Thermal Blue and Thermal Blue Blaze.

Selecting Local Seed Products:
The number of seed products being sold over-the-counter and through seed houses can be overwhelming. However, by looking at the seed tags on products, the selections can be narrowed if one is looking for a specific blend or mixture. Keep in mind that seed products are packaged for national sales and are excellent products for many areas of the country. However, that does not mean that all seed products grow well in all areas of the country.

Brand names of Kentucky bluegrass blends from several vendors can be found in Table 2. These blends can contain 2 or more varieties of Kentucky bluegrass. Be sure to inspect the seed tag pasted on the back of the bag to identify the varieties of Kentucky bluegrass making up the blend.

Table 2. Kentucky Bluegrass Blends
Brand Names	Vendor
Best of the Blues	Hummert International
Scott’s Classic Kentucky Bluegrass Seed	Lowe’s, Home Depot
Pennington Kentucky Bluegrass Lawn Seed Blend	Lowe’s
Tournament Quality Kentucky Bluegrass Lawn Seed Blend	Lowe’s
Pennington Kentucky Bluegrass Penkoted Lawn Seed	Lowe’s
Scott’s Turf Builder Kentucky Bluegrass Grass Seed	Home Depot

The mixture mentioned early on in this article with tall fescue and Kentucky bluegrass has several nice combinations available over-the-counter or through seed houses. Many venders market a 90/10 combination by volume of tall fescue and Kentucky bluegrass and are an excellent choice for Missouri. Mixtures can also be made by purchasing a blend of turf-type fescues and a blend of Kentucky bluegrass (Table 2) and combining them in a ratio of 9:1 by volume. Some of the branded mixtures on the market are listed in Table 3.

While we are seeing less Kentucky bluegrasses in Missouri, it is still part of our landscapes and grounds. Annual and rough bluegrasses are primarily considered weeds in Missouri even though they are considered desirable species in other regions. Any of the varieties or brand named products listed in tables 1 to 3 should provide acceptable performance in Missouri. Any additional questions can be directed to fresenburgb@missouri.edu.

Reference:
Turgeon, A.J., Turfgrass Management (7th edition), Prentise Hall, 2004.