Take a close look at your lawn and you may discover it is made up of more than one type of grass. In Idaho, lawns are typically a blend of cool-season grasses, with each species contributing different characteristics. Knowing what grasses make up your lawn can help you better understand how it grows and responds to changing conditions throughout the year.
The four grasses most commonly used in Idaho lawns are Kentucky bluegrass, perennial ryegrass, tall fescue, and fine fescues.
Two Basic Growth Patterns
Lawn grasses have two basic growth habits: bunch-type and spreading.
Bunch-type grasses grow in clumps and spread very slowly. If damaged, they generally do not fill in bare areas on their own.
Spreading grasses produce underground stems called rhizomes that allow them to spread and gradually fill in damaged or bare areas. This growth habit also means they may spread beyond the lawn into landscape beds or other areas.
Kentucky Bluegrass
Kentucky bluegrass does not perform as well in shade and may develop thatch, a layer of living and dead plant material that accumulates near the soil surface.
Identification
- Rounded, boat-shaped leaf tip
- Folded leaf with two grooves running along the midvein, giving the appearance of "train tracks"
- Medium to dark green color
Perennial Ryegrass
Perennial ryegrass is a bunch-type grass. It is known for its rapid germination and good traffic tolerance, making it a common component of lawn seed mixtures. It produces little thatch because it does not spread by rhizomes.
Perennial ryegrass is generally less winter hardy than Kentucky bluegrass and is better adapted to lower elevations of southern Idaho than colder mountain regions.
Identification
- Folded leaves with a glossy underside that appears shiny in the light
- No "train track" grooves on the leaves
- Often has a reddish-purple color at the base of the stem
Tall Fescue
Tall fescue is a bunch-type grass. It has good traffic tolerance and is more cold tolerant than perennial ryegrass, although generally not as cold hardy as Kentucky bluegrass. Its deep root system contributes to its heat and drought tolerance. Tall fescue also has good shade tolerance and typically remains where it is planted because it does not spread by rhizomes.
Identification
- Broad, coarse leaf blades
- Prominent veins
- Stiff leaves with slightly rough or serrated edges
Fine Fescues
Fine fescues are a group of bunch-type grasses that are often considered lower maintenance. They are very cold tolerant, have good drought tolerance once established, and tolerate shade better than the other grasses commonly used in Idaho lawns. They also perform well in less fertile soils.
Identification
- Very narrow leaves folded in half, resembling a pine needle
- Fine texture
- Often has a reddish-purple color at the base of the stem
Why Are Grass Mixtures Common?
Most Idaho lawns are planted with a blend of two or more grass species. Each species contributes different characteristics, such as winter hardiness, wear tolerance, drought tolerance, or shade tolerance. This combination helps lawns perform under a variety of growing conditions found throughout Idaho.
Learning to recognize the grasses in your lawn is the first step in understanding how they grow and why they may respond differently to weather, foot traffic, or seasonal changes.
Resources
- University of Idaho Extension. Lawns. https://www.uidaho.edu/extension/horticulture/landscapes/lawn
- University of Kentucky Cooperative Extension. Identifying Turfgrasses in Kentucky.https://publications.mgcafe.uky.edu/files/AGR251.pdf
