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Kentucky bluegrass (lawn)

Poa pratensis · Poaceae

Most common cool-season lawn grass in the northern US

Kentucky bluegrass (lawn)

Photo: Ethan2039, CC BY-SA 4.0, via Wikimedia Commons

Sun
Full sun; tolerates light or partial shade
Soil
Well-drained, moist loam
Soil pH
Slightly acidic to neutral, about 6.0-7.0; also tolerates neutral to alkaline soil
Water
About 1-1.5 in per week in the growing season. Goes dormant in drought
Hardiness
USDA zones 3-7; cool-season grass
Height and spread
Mow at 2-3.5 in. Spreads by rhizomes

Guv's tipMow bluegrass at 2-3.5 inches, higher in summer heat. Seed in late summer to early fall, mid-August to mid-September.

Through the year

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Sow or plant
Harvest

Months are a rough guide. Time it by your own frost dates.

When to plant

Seed in late summer to early fall (mid-Aug to mid-Sep; overseed Aug 15-Sep 1). Lay sod during the growing season

Harvest or flowering

Flowers late spring to early summer (flowering starts in May, seed mature by mid-June). Rarely seen in regularly mown lawns

Pruning

Mow regularly at 2-3.5 in, higher in summer heat

Making more plants

Seed or sod; spreads by rhizomes

Watch out for

Pest

White grubs (e.g. Japanese beetle larvae)

Look for: Brown patches; turf lifts like carpet

What to do: Labeled grub control: preventive in June when adults lay eggs, or curative after rain when grubs feed near the surface

Disease

Summer patch

Magnaporthiopsis poae

Look for: Orange-brown to straw circular patches/rings of dead turf in summer

What to do: Mow at about 3 in, water deeply and infrequently, core aerate, use balanced nitrogen and resistant cultivars. If severe, apply a fungicide preventively (when soil is above 65°F)

Always read and follow the label on any treatment, and check it is approved for use where you live.

Safety and spread

Pets and people: Not listed as toxic by the ASPCA or the University of California toxic plant list

Weed risk: Not on the federal noxious weed list

Checked against two or more reputable gardening sources. How we check our facts
Keep it by the back door

The Plant Doctor and the Guv's book

Printable pest and disease charts with real photographs, and all 50 USA plants in one book.

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