Turfgrass Considerations for Reducing Water Use in Lawns

Photo: Abiya (Abi) Saeed

Turfgrass refers to grasses that grow in a uniform manner to form dense and even coverage in a landscape, and are primarily used for lawns, athletic fields, and golf courses. Of the 11,000 species of grasses worldwide, only a few fit the characteristics of ideal “turfgrass.” In Montana, these species include Kentucky Bluegrass, Fine Fescues, Tall Fescue, and Perennial Ryegrass. These cool season turfgrass species grow best during temperatures of between 50-75F (with soil temperatures being just as important as air temperatures).

Before we get into the grasses, it is important to mention that one of the best ways to save water in residential lawn systems is to focus on the efficiency of irrigation systems, watering plants during appropriate times to reduce evaporation and wind drift, and appropriately adjusting watering strategy based on environmental conditions including shade, cloud cover, and rain. This includes regularly checking irrigation systems and weather, incorporating rain sensors, and avoiding the reliance on fixed irrigation schedules. For more information, reach out to local irrigation suppliers for details on water-saving technologies that can be utilized in irrigation practices.

General irrigation requirements of certain plants can motivate home gardeners and landscapers to look for plants that may require less water, potentially making them a better fit for a lower maintenance landscape. Although Montana’s cool season turfgrasses share many similarities, there are also plenty of differences in the amount of irrigation, fertilizer, mowing heights, landscape suitability, and wear-and-tear tolerance. When purchasing grass seed, many also opt for incorporating a mix (multiple species mixed together) or a blend (multiple varieties within the same species), which helps when there are variations in microclimate and shade within a landscape, and helps reduce pest and disease susceptibility and increase overall vigor. Regardless of the turfgrass species, seed and sod both require frequent irrigation until establishment.

In Montana’s cool and semi-arid climate, the natural cycle for cool season turfgrasses is to green up in the spring, go dormant and turn brown in the late summer to protect from damage due to high temperatures and limited moisture availability, and then resume green growth again in the fall until winter dormancy. Some opt to reduce summer turfgrass irrigation and encourage the onset of dormancy, which can save money and prioritize water use for other plants in the landscape. Letting cool season turfgrasses go dormant does not usually adversely affect the health of turf, though extended periods of hot and dry conditions can still dehydrate the plants which continue to lose moisture even during dormancy.

If choosing to let turf go dormant in the summer, give a light sprinkle of water (about ½ inch) once or twice a month if there has been no precipitation. This will not cause the grass to green, but will prevent it from drying out until cooler temperatures and precipitation in the fall. Do not let turf go in and out of dormancy during summer, which can cause it to become stressed, leading to patchy and unhealthy turf that is more susceptible to pest and disease issues.

Photo: Abiya (Abi) Saeed

Although summer dormancy is a natural component of the cool season turfgrass life cycle in semi-arid landscapes like much of Montana, many may not appreciate the look of a brown lawn during the summer months. Another option for reducing water use in turfgrass lawns is to opt for a turfgrass species or variety with lower water needs. Kentucky bluegrass (KBG) is the most commonly used turfgrass in cool climates throughout the country, and Montana is no exception. Chosen for impressive cold hardiness, dense rhizomatous growth, high tolerance for wear and tear, and attractive green color, it can be found in many landscapes large and small. To maintain a healthy, functional, and resilient KBG lawn, the inputs (which include mowing, fertilizing, aerating, and especially water needs) can be fairly high. KBG lawns can require 2 or more inches of water per week in the heat of summer when temperatures are warm and conditions are drier. Replacing KBG with turf-type tall fescues or fine fescues like creeping red and Chewings fescue are popular choices that can reduce those irrigation needs by 40-50 percent depending on the landscape and soil conditions. Turf-type tall fescues and fine fescues can also be lower maintenance in terms of fertilizer needs. Sheep fescues and hard fescues are types of fine fescues that are well suited to semi-dryland lawns, though they don’t mix well with other turfgrass species because of their differing growth habit and texture.

Although perennial ryegrass seeds are a common component of turf lawn seed mixes, due to their quicker germination rates and fast establishment periods, this species of turf is not very suitable as the primary or dominant lawn species in Montana, because it will thin out within 1-2 years, requiring frequent re-seeding to maintain good coverage.

Some of our native grass species have also been adapted to fit the aesthetic of a home lawn, and may be even lower maintenance, and require less water, than any of the traditional turf varieties mentioned above. These native turfgrasses are warm season species and stay dormant well into the spring, greening up much later than their cool season counterparts. They also have significantly lower water needs after establishment, and are less likely to experience symptoms of heat and drought stress. If low water needs are a primary consideration for your lawn and dormant turf does not bother you, warm season turf including the native buffalograss and Blue Grama species may be a great fit.

Regardless of the turfgrass choices, caring for turfgrass includes: maintaining a healthy (but not too low) mowing height, deep and infrequent watering to encourage deeper rooting and drought resilience, aerating semi-regularly (especially if soil compaction is an issue), and fertilizing based on the individual needs of turfgrass. These are vital to the overall health and performance of turfgrass lawns.

Abiya (Abi) Saeed is the MSU Extension Horticulture
Specialist.