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Cool Season Grass Selection

Sustainable home lawns are designed, constructed and maintained to minimize any adverse effects to the environment while reducing resource inputs. That is, a lawn area should remain relatively healthy given the existing site conditions with minimal need for additional resource inputs. The goal of any lawn care program is to provide the necessary resources (e.g., water, nutrients) to promote plant health and vigor. This allows the lawn to successfully compete against weed invasion and quickly recover from modest levels of injury due to pest damage, play, or other use. In addition, a healthy lawn retains the positive environmental functions of stabilizing the soil against water and wind erosion. The successful establishment of a sustainable lawn requires an evaluation of current site conditions as well as the desired quality and use expectations for that lawn area. Remember, even high use lawns that require the use of high maintenance turfgrass varieties can be sustainable. The necessary inputs to preserve plant health will just be higher.

Several maintenance levels are described in Table 1. These are used as a guide to determine existing maintenance levels and the procedure required to change to a different level. For the most part, the grass varieties present, along with any site restrictions, (e.g., shade, sandy soils, clay soils, poorly drained areas) determine the maintenance level necessary for the lawn to remain healthy.

Table 1. Levels of Home Lawn Care

Lawn Care Level

Amount of Watering

Range of Mowing Heights

# of Fertilizer Applications

Timing of Fertilizer Applications

Very Low Maintenance:

(see grass types under low maintenance)

none

3+

0

-------

Low Maintenance:

Suitable grasses are common Kentucky bluegrass varieties & fine-leaved fescues (e.g., creeping red, chewings and hard fescue)

little to none

2 1/2"-3

1

September

Medium Maintenance:

Suitable grasses are most Kentucky bluegrasses & fine-leaved fescues

some

2"-3"

2

Mid- to late August early September, mid-October

High Maintenance:

Suitable grasses are the improved bluegrass varieties & turf-type perennial ryegrasses

regularly

1"-3"

3 or 4

Mid-May to mid- June, mid-August, mid-September, and mid-October


In many instances, transition to a more sustainable lawn will only require an adjustment in present maintenance practices. Sometimes a complete renovation or creation of a new lawn will be necessary. Identifying the grasses present on a site will be very helpful in determining an appropriate course of action. Following are general guidelines to help determine your present lawn makeup.


1. If your lawn is older than 30 - 35 years, chances are it consists mostly of common types of Kentucky bluegrass and fine-leaved fescues. The fine-leaved fescues will dominate the shady areas while the Kentucky bluegrasses will be more dominant in the sunny areas.

2. If your lawn was established by seeding or overseeded with mixtures designed for "general purpose lawns," Kentucky bluegrasses, fine-leaved fescues and perennial ryegrasses are probably all present.

3. If your lawn has been established or overseeded with grass seed blends for "premium or elite" lawns, the lawn will be a mixture of several improved Kentucky bluegrass varieties along with some perennial ryegrass. These grasses are better adapted to high maintenance and do not perform well in low maintenance programs. The introduction of low maintenance species and varieties is necessary when a lower maintenance program is desired.

4. If your lawn was established by sodding, the grasses present will be Kentucky bluegrasses. Recently, sod blends have included some higher maintenance varieties and some tolerant of lower maintenance. This allows the sod to adapt to a variety of maintenance levels. This situation may or may not need to be overseeded with some additional grass types tolerant of low maintenance programs.


The most important first step in creating a more sustainable lawn is to match the specific lawn grasses with the anticipated or desired level of lawn care. Of course, the level of lawn care will, in large part, be determined by the amount of traffic and use. In the landscape industry, this concept is known as putting the right plant (e.g., tree, shrub or lawn) in the right place. For example, trees and shrubs adapted to sandy, well-drained, drier soils will usually die when placed in wet, poorly-drained soils. While one may desire to grow a particular plant or cultivar, the site conditions must be appropriate for it to grow and provide the desired landscape effect. This same principle can also be applied when selecting turfgrasses.


Selecting Cool Season Lawn Grasses for the Establishment of Sustainable Lawns in the Upper Midwest

Kentucky Bluegrass (Poa pratensis)Kentucky bluegrass is the most widely used cool season grass planted in northern portions of the United States. Kentucky bluegrass has a number of desirable adaptations over other lawn grasses. The strong rhizomatous nature of Kentucky bluegrass allows it to quickly establish an area and repair itself from damage due to pests and use. Kentucky bluegrass will form a relatively dense lawn of good green color that mows cleanly. Kentucky bluegrass is adapted to a wide range of environmental conditions but does best in soils of moderate to high fertility and soil pH of 6 to 8. When mowed at 2 to 3 inches, Kentucky bluegrass is very competitive against weed invasion. It is best suited to lawn areas receiving full sun to light shade.Two disadvantages are its rather shallow root system and relatively high demand for water. However, older, "common" types of Kentucky bluegrass but few of the modern elite bluegrass varieties have the ability to survive extended drought periods by going into dormancy. During dormancy, the plant can lose its leaf tissue (as evidenced by the plant turning brown) and most of its root system. However, the crown and rhizomes remain alive for much longer and are responsible for the recovery observed when watering or rainfall is resumed. During extended periods of very dry conditions and very high temperatures, some water may be necessary to prevent permanent injury to the crowns and rhizomes. Once these are permanently damaged, the plant will not recover even if watering is resumed or rainfall becomes more frequent.Many varieties of Kentucky bluegrass have been developed, each differing in aggressiveness, tolerance to low mowing heights, resistance to various diseases, shade tolerance, and level of management required. Although all the differences in individual varieties are beyond the scope of this program, it may help to group some of the varieties according to suitability for low or high maintenance lawns.

Kentucky bluegrass varieties are often divided into two groups: common types and improved or elite types. Common varieties or "public varieties" as they are known in the seed industry, are older varieties (or selections from older varieties) that have been around for many decades. Up until the late 1960s, common types of Kentucky bluegrass were the predominant types grown in home lawns. Table 2 lists the major plant and use characteristics of common bluegrasses.


Table 2. Plant and Use Characteristics of Common KB Varieties

Plant Characteristics of Common Kentucky Bluegrass

  • Medium to medium-dark green color
  • Medium texture
  • Growth habit rhizomatous but taller and more upright
  • Will go dormant during hot, dry periods; recovers when moisture supplied
  • Dormancy does have physiological limits that, once exceeded, recovery does not occur

Use Characteristics of Common Kentucky Bluegrass

  • Little to no shade tolerance Lower wear tolerance than improved types
  • More drought tolerant than many improved types
  • Lower moisture and fertility requirements than most improved types
  • Example varieties: Park, Kenblue, South Dakota Certified, and "Common"

For the most part, improved or elite Kentucky bluegrass varieties have been developed in the last 30 to 40 years. Since most of the introductions to date have been selected under systems of generally high fertility and ample moisture, many have limited use in low-maintenance landscapes. However, there is an increasing amount of research being conducted to improve the water and nutrient conservative nature of improved types. As this continues, it is likely that improved varieties, with their superior disease tolerance, will also have increasing levels of tolerance to environmental stresses and lower fertility levels. Table 3 lists the major plant and use characteristics of improved bluegrasses.


Table 3. Plant and Use Characteristics of Improved KB Varieties

Plant Characteristics

  • Medium dark to dark green color
  • Medium to medium coarse texture
  • Low spreading growth habitBroad disease tolerance or resistance
  • Vigorous rhizomatous growth giving good stand density

Use Characteristics

  • Little to no shade tolerance
  • Good wear tolerance and recovery potential from injury
  • Higher maintenance requiring ample water and fertilizer for optimum health
  • Need for more frequent dethatching
  • Poor soil conditions (i.e., compaction, waterlogging) increases vulnerability to various root disease

It should be noted that where the landscape situation calls for the maintenance of a green lawn surface throughout the growing season and ample moisture and fertility can be provided, then it would not be a sustainable turfgrass choice to select common types of bluegrass for that situation. Under those conditions, common types of bluegrass are more prone to disease and generally do not perform as well, thereby potentially increasing weed invasion and an increased need for herbicides. Those improved cultivars adapted to higher and lower maintenance levels are based on research at Iowa State University as listed in Table 4.


Table 4. Examples of Some Cultivars Adapted to Higher Maintenance Levels

Examples of Some Cultivars Adapted to Lower Maintenance Levels

Midnight

Ram I

Merit

Eclipse

Aspen

Baron

Columbia

Vanessa

Rugby

Banff

Nugget

Touchdown

Parade

Geronimo

Kenblue

Argyle

South Dakota Common

Vanessa

Fylking

Monopoly

Ram-I

Harmony

Barblue

Parade



For more on Kentucky Bluegrass, see:

Fine-leaved Fescues (Festuca spp.)

The term "fine-leaved fescues" is generally applied to three similar species commonly used in our lawn mixes. There are creeping red fescue (Festuca rubra spp. rubra), chewings fescue (Festuca rubra var. commutata) and hard fescue (Festuca longifolia). Occasionally, sheep fescue (Festuca ovina) is utilized in mixes to be used in very low-maintenance areas. Creeping red fescue does spread by rhizomes but is not nearly as aggressive as Kentucky bluegrass. Chewings fescue and hard fescue are considered bunch-type grasses as they lack rhizomes or stolons and spread primarily by tillering. Table 5 lists the major plant and use characteristics of fine-leaved fescues.


Table 5. Plant and Use Characteristics of Fine-leaved Fescues

Plant Characteristics

  • Chewings, Hard and Sheep fescues are all bunch-type grasses
  • Creeping Red is rhizomatous but less so than Kentucky bluegrass
  • Medium to slow growth rates
  • Medium to dark green color
  • Fine to very fine in texture

Use Characteristics

  • Shade tolerant
  • Drought tolerantLow moisture and fertility tolerant
  • Less tolerant of high wear conditions
  • Does not mow well in pure stands, better mixed with bluegrasses


Fine fescue species and their respective cultivars are well adapted to our northern climate. There should be little difficulty in successfully growing the fine-leaved fescues in our area. They are also good to include in a lawn seed mixture when introducing low-maintenance varieties into an existing lawn or establishing a new lower maintenance lawn. Fine fescues are not normally sold or grown as sod.Perennial ryegrass (Lolium perrene)Perennial ryegrass is a cool season, medium-textured, wear tolerant, bunch-type grass. It is a high-maintenance grass well adapted to areas receiving high amounts of foot traffic such as athletic fields or intensively used backyards. One of the biggest drawbacks of perennial ryegrass usage for some parts of the northern plains region is its poor cold tolerance. It is considered the least hardy of our cool season lawn grasses and can thin out significantly or be completely killed during cold, open winters. Varieties currently available that have shown good cold tolerance to date include: Blazer, Delray, Diplomat, NK200, and Pennant.

In a pure stand, the tough fibrous nature of the blades makes it more difficult to mow cleanly. Therefore, it is always important to mow with a sharp mower blade. The newer, "turf-type perennial ryegrasses" have been selected and developed to blend well with other types of lawn grasses, especially Kentucky bluegrass. These are the ones that should be used when considering perennial ryegrass use in a seed mixture. They are normally not sold or grown as sod. Table 6 lists the major plant and use characteristics of turf-type perennial ryegrasses.


Table 6. Plant and Use Characteristics of Turf-type Perennial Ryegrass

Plant Characteristics

  • Bunch-type growth habit
  • Moderate to rapid growth rate, good rooting potential
  • Germinates quickly allowing for rapid establishment, "nurse" crop role
  • Turf-types are medium to medium-fine in texture
  • Medium to dark green color with shiny leaf undersides
  • Can complete excessively in mixed seedings

Use Characteristics

  • Performs best in medium to high-maintenance programs
  • Drought tolerance (?)
  • Little to no shade tolerance
  • Can encounter rust problems under low N fertility and normal water
  • Mixes well with improved Kentucky bluegrass varieties
  • Tends to be thin, become clumpy and coarser texture under low maintenance


Perennial ryegrass is known for its rapid germination and establishment and is therefore useful where quick repair and establishment of a turf cover is needed. A related drawback of this characteristic is that it can quickly shade and overpower slower germinating grasses seeded at the same time. To the unobservant, the bluegrasses and fine-leaved fescues may be totally lost from the stand due to the excessive competition from perennial ryegrass.

Because of its bunch-type growth habit, it does not spread rapidly. When seeding areas with mixes containing more than 50 percent perennial ryegrass, increased seeding rates will be necessary to quickly cover an area. If perennial ryegrass is allowed to thin out due to improper maintenance, the turf becomes bunchy and loses quality. If the degree of soil exposure is increased on sloped areas due to thinning out, there is an increase in the potential for erosion and thereby the potential for pollution of nearby lakes, streams, and rivers. Remember, grasses are one of the very best stabilizers of soil when they are maintained in good health and completely cover the soil surface.

For more on Perennial Ryegrass, see:

Grasses Not Generally Suited to Home Lawns in Minnesota

Annual ryegrass has been widely used as a temporary grass in lawn mixtures. It is short-lived and not recommended for lawn use since the plants will all die during the winter. Where a temporary cover is needed during the growing season, such as in areas used as ice rinks, this may be a suitable, cost effective choice.

Turf-type tall fescue varieties are suitable for athletic fields and low-maintenance lawns in some areas of the country, but do not have sufficient cold tolerance for Minnesota conditions. Further testing and variety development may lead to varieties of tall fescue that will consistently withstand Minnesota winters. At present, tall fescue is not recommended for Minnesota lawns.

Creeping bentgrass is adapted for golf course use and requires a great deal of care. Since it can be mowed down to less than 1/4 of an inch, it is ideal for golf greens. However, creeping bentgrass requires too much maintenance to be acceptable in most home lawn situations. In fact, bentgrass patches in Kentucky bluegrass lawns are a major weed problem in the northern United States.

Zoysia grass is a warm season grass commonly advertised for use in this area. While zoysia will often survive our winters, its warm season growth habit doesn't allow it to turn green until the warm temperatures of late spring to early summer. It again turns brown with first cool weather of late August to early September. Also, without sufficient water during the growing season it remains rather brown during the growing season as well. It is also very slow to establish a lawn due to the relatively short and often cool summer conditions.

Buffalograss is a very drought tolerant, warm season grass native to many of the short-grass prairies of the great plains. It is a very low-maintenance turfgrass, growing only 6 to 8 inches high. There is considerable research being done to evaluate its use in areas with more humid growing conditions where it is very difficult to establish and often short lived. It could be considered an alternative grass in west central to southwest Minnesota. Again, through continued evaluation and research it is likely that its range of successful adaptation and use will be expanded.

Sustainability of a lawn area does not necessarily mean a lawn with very low-maintenance requirements. Selecting the right plant, adapted to the maintenance that will be performed on that site, is critical to creating a sustainable condition. The wrong species or varieties placed under conditions for which they have not been developed or selected will only increase the need for maintenance and may even result in outright failure of the lawn. Where much lower maintenance is desired, the first step in the program may be to introduce turf varieties adapted to those conditions before a sustainable condition for that site is achieved. Remember, right plant - right place - right function is just as important for our lawn grasses as tree, shrub, and flower placement.

For more on grass seed selection, see:


 

 
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