Kentucky Bluegrass, Fescue or a Blend for a Montana Lawn

What is the difference between bluegrass and fescue?

Kentucky bluegrass is a sod-forming grass. Colorado State University Extension's turfgrass selection guide lists its advantages as underground rhizomes, high recuperative potential, soft easily mowed leaves, high color and density, ready availability as sod, and excellent heat and cold tolerance. Rhizomes are the reason a bluegrass lawn fills in a worn spot on its own: the plant sends shoots sideways under the surface.

"Fescue" covers two quite different groups. The fine fescues (creeping red, Chewings, hard and sheep fescue) have narrow, dense leaves, tolerate shade and poor soil, and want little nitrogen. Turf-type tall fescue is a wider-bladed grass bred from a pasture species for lawn use; CSU describes it as deep-rooted, wear-tolerant and slow to form thatch. When someone in Montana says their lawn is "half fescue," it matters which one they mean.

What does MSU Extension recommend for Montana lawns?

MSU Extension's MontGuide on planning and planting lawns says it is better to plant a mix of species because of variations in microclimate and shade. For general lawn use under moderate irrigation, sun and fertility, it recommends Kentucky bluegrass (or an improved cultivar), creeping red or Chewings fescue, and perennial ryegrass. A typical mix is about 60 percent Kentucky bluegrass, 30 percent red or Chewings fescue and 10 percent perennial ryegrass.

The ryegrass in that mix is a nurse grass. MSU notes it is not permanent and that including it is optional; it germinates fast and holds the soil while the slower bluegrass establishes. MSU also warns that mixes containing a large percentage of perennial or annual (Italian) ryegrass make inferior lawns in Montana, so read the label on a bag of "sun and shade" seed before you buy it.

Is Kentucky bluegrass really a water hog?

Less than its reputation suggests. CSU Extension's note on bluegrass drought tolerance says the grass can stay green and healthy on far less water than most people assume, and that it survives long dry periods through an excellent dormancy mechanism. CSU observed that lawns which died during drought had mostly been poorly managed beforehand, damaged by mites, or planted on poorly prepared soil.

What bluegrass does need is depth. MSU's maintenance MontGuide says frequent light watering produces shallow roots and less drought tolerance, and recommends watering deeply and infrequently in the early morning. A bluegrass lawn that browns in a dry August is often a lawn that was watered every day in June. If you want to plan for summer browning on purpose, see our guide to letting a lawn go dormant in drought.

Where do fine fescues beat bluegrass?

Shade and low input. CSU rates the fine fescues as having very good shade tolerance, preferring low nitrogen fertility, tolerating rocky, sandy or clay soil, being very cold tolerant and making an excellent high-elevation grass. CSU's PlantTalk on shade says Chewings and creeping red fescue tolerate light shade quite well, while some bluegrass varieties have only fair shade tolerance.

That is why MSU's shade mix flips the proportions: about 60 percent creeping red or Chewings fescue, 30 percent Kentucky bluegrass and 10 percent perennial ryegrass, mown at about 2.5 to 3 inches. Under the big ponderosas and maples that shade so many Missoula and Bitterroot yards, a fescue-heavy blend is usually the only grass that stays thick.

Fine fescues have limits. CSU lists only moderate wear tolerance, slow recovery from traffic, a tendency to lie down and resist mowing, and possible dormancy during extended heat in the 90s. A fine fescue lawn is not the right choice for a dog run or a side yard that doubles as a soccer field.

Does turf-type tall fescue work in western Montana?

It can, with caveats. MSU's planting MontGuide lists the newer turf-type tall fescues, along with sheep and hard fescue, for semi-dryland lawns in eastern Montana, and says these grasses differ enough in growth habit and texture that they are best planted alone rather than mixed. Tall fescue is a clump former, so it does not blend invisibly into bluegrass.

CSU's PlantTalk on tall fescue explains why the drought claims do not always hold: tall fescue saves water because its roots go deep, but on shallow, gravelly or heavy clay soils that stop deep rooting, it may need as much water as bluegrass or more. Much of the Bitterroot floor is cobbly, shallow ground, so the soil under your yard matters more than the seed tag. Our sibling guide to Bitterroot Valley soils explains how to find out what you have.

There is also a wrong kind of tall fescue. CSU discourages "K-31" or "Kentucky 31" for lawns, and its PlantTalk on tall fescue as a weed describes pasture-type clumps in bluegrass lawns that are tough to mow and green up earlier than the grass around them. If your lawn has coarse clumps a foot or two across, that is probably what they are.

Which grass handles traffic, dogs and kids best?

Bluegrass and tall fescue, for different reasons. Bluegrass recovers because its rhizomes regrow into damaged spots; CSU lists high recuperative potential as a key advantage. Tall fescue resists wear but does not spread, so CSU notes heavy use by children or pets can leave worn areas that need overseeding. Perennial ryegrass is wear tolerant and establishes fast but has poor recuperative potential, which is why it is used in small amounts.

For dog owners specifically, the grass is only part of the story. Our guide to dog spots on the lawn covers which grasses patch well into a bluegrass lawn and why water is the only thing that helps.

What are the trade-offs on maintenance?

CSU's selection guide lists bluegrass disadvantages honestly: it forms thatch, has more disease (leaf spot, necrotic ring spot, Ascochyta leaf blight), more frequent insect problems (billbug, grubs, mites), poor to fair salt tolerance, a higher nitrogen requirement than other grasses, and it will invade flower and vegetable gardens. Fine fescues ask for less fertilizer but can also build thatch and are susceptible to red thread, leaf spot and dollar spot.

In practice, the maintenance gap is smaller than the seed catalogs suggest. Every one of these grasses does best with the same basics MSU recommends: mowing at 2.5 to 3 inches, removing no more than a third of the blade, deep infrequent watering and most of the fertilizer in fall. Our guides to mowing height and Montana lawn fertilizer rates and timing cover those.

What about low-water and non-irrigated grasses?

For very dry or non-irrigated ground, MSU lists Fairway or Roadcrest crested wheatgrass, streambank wheatgrass, and meadow and smooth bromegrass, noting they brown during drought and should not be mown below 3 inches. It mentions buffalograss and blue grama as low-water options that green up slowly in spring and brown soon after the first fall cold, and cautions that neither competes with weeds or cool-season grasses in irrigated lawns.

MSU is also clear about two grasses sold as cold and drought tolerant: zoysiagrass and Bermuda grass are not appropriate for Montana lawns. Our ranked list of the best lawn grasses for Montana profiles each option in more detail.

How do I choose the mix for my yard?

Walk the property and split it by conditions rather than picking one seed for everything. Full sun with irrigation and regular use: a bluegrass-dominant blend in the proportions MSU describes. Shade under trees: the fescue-dominant shade mix. A dry slope or field edge you will not water: one of the dryland grasses, or a planting that is not lawn at all, which our guide to replacing some lawn with native plants covers.

When overseeding an existing lawn, match what is there. CSU's renovation note advises choosing a grass species compatible with the existing lawn; dropping tall fescue into fine bluegrass produces a patchwork. For a new lawn, our guide to sod or seed explains that sod limits your choice, since most sod sold is bluegrass-based.

Where HJ fits in

We seed and overseed with cool-season mixes suited to western Montana as part of our aeration and overseeding service, and we can tell you which areas of your yard are fighting the wrong grass. Our licensed fertilizer and weed control program and recurring lawn care are built around how these grasses actually grow here. This guide is part of our Montana Landscaping, Lawn & Irrigation Guide. For a look at your lawn, call (406) 215-7319 or request a free estimate.

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