Parent Species:
Common Kentucky Bluegrass
The original, unimproved Kentucky bluegrass — upright, pale and full of seedheads by late spring, which is how you spot it.
Is Common Kentucky Bluegrass Right For Your Yard?
Best For:
Tradeoff:
What It Is And How To Tell It Apart
If your bluegrass grows upright and open rather than low and dense, throws seedheads early and heavily, and thins every cool wet spring, it is a common type. Nobody chooses these for a lawn — they arrive in cheap seed, or they were already there.
Common types are the unimproved Midwest ecotypes: plants collected from old pastures and wild stands rather than bred. They are one end of the same species as ‘Midnight’, so the leaf tip is still boat-shaped and it still runs white rhizomes. What differs is everything a plant breeder would have fixed.
| What you see | Why it happens |
| Upright, open growth and narrow blades, medium to light green rather than dark | No selection for low, dense growth or for genetic color — these were field plants, not turf plants |
| Heavy seedheads in late spring, so a mown lawn looks stemmy and speckled | Common types set seed earlier and more freely than improved ones. That is why they are cheap to produce, and why they persist commercially |
| Purple-brown lesions on the blades in cool, wet weather, then patches thinning out | Leaf spot and melting-out. Improved cultivars were bred against this disease specifically; common types have essentially no resistance |
| Thins rather than thickens when you mow it short | It will not hold below about 2 inches. An improved compact type gets denser at that height; this gets sparser |
| Browns off or discolors through winter | Poor winter color is a group trait. It is a color problem, not a survival problem — cold hardiness is the same across every bluegrass type |
| Goes brown early in a dry summer, ahead of every other lawn on the street | It quits sooner. In the Kansas State deficit-irrigation work it wilted fastest of all the bluegrass types |
Names to recognize on a seed label: Kenblue, Park, Newport, Delta, South Dakota Certified, Huntsville, Geary, Alene, Piedmont, Ginger, Garfield, S-21, Argyle, Cache, Wellington, Voyager and Ronde.
One distinction worth keeping straight. Common type is not the same as VNS, the label term for variety not stated. A common type is a named, known, unimproved variety. VNS means the identity is not being declared at all, and it could be anything. Both are reasons to put the bag down; they are different reasons.
How It Got Here
Before 1947, this was all there was. Commercial bluegrass seed was harvested from wild stands in the Midwest, often from pastures, and sold simply as Kentucky bluegrass.
The named common varieties came out of that same material rather than out of a breeding program. ‘Delta’ was released by the Canada Department of Agriculture in 1938, ‘Troy’ by the Montana Agricultural Experiment Station and USDA in 1955, and South Dakota Certified comes from naturalized common-type seed fields. ‘Kenblue’ was released in the late 1960s by the University of Kentucky and USDA Agricultural Research Service, built from seed collected in central Kentucky fields that had been in bluegrass for eight to fifteen years. The University of Kentucky still publishes it — in a bulletin about bluegrass as a forage crop, which tells you plainly what it was selected for.
The turn came with ‘Merion’, spotted at a Pennsylvania golf club in 1936 and released in 1947 as the first improved Kentucky bluegrass cultivar. Leaf spot and melting-out were doing so much damage to common-type turf that breeding against that single disease became the founding purpose of modern bluegrass improvement. Everything on the other four bluegrass pages descends from that effort.
Common types survive in the market for one reason: money. They set seed early and yield heavily, which makes them the cheapest bluegrass per pound to grow. So they end up as filler in bargain lawn mixes and low-cost utility blends, where the front of the bag says Kentucky bluegrass and the analysis label on the back says which kind.
What To Do About It
It depends entirely on what the site is. Common bluegrass is a poor lawn grass and a genuinely useful conservation grass, and the same traits produce both verdicts.
- If it is a field, a bank, an acreage or an unirrigated back paddock, leave it. It holds soil, survives on rainfall by going dormant, and gets by on 1 to 2 lb of nitrogen per 1,000 sq ft a year. Extension recommends common types for soil stabilization and conservation on exactly these grounds. Replacing it would cost money to make the site worse.
- If it is your lawn and you want it denser, do not try to force it. Raise the mower to 2.5 to 3 inches and never go below 2, feed in fall rather than summer, and overseed in late summer with improved cultivars at 1.5 to 3 lb per 1,000 sq ft. Repeat for two or three falls. The improved material is denser and will gradually take the space, because the common type cannot out-compete it.
- Do not reach for a fungicide when it thins in spring. The thinning is the variety, not an outbreak you can spray your way out of. Overseeding is the fix.
- If you are buying, the whole problem is one line on the label. Read the analysis panel, not the front of the bag. Named improved cultivars and a blue certification tag mean you are getting turf-type material; Kenblue, Park, Newport or ‘variety not stated’ means you are not.
- Price is the tell. A bag of 100% Kentucky bluegrass priced far below the others on the shelf is usually cheaper for this reason.
- And it is still sold deliberately, under its own name. Kenblue is stocked as bulk coated seed by farm-seed suppliers and turns up in 1 lb and 5 lb packs from online sellers — sometimes with retail copy that borrows improved-type language, describing it as an aggressive variety that makes a dense sod with early spring green-up. Buying it is easy, which is the whole reason this page exists.
Two honest footnotes. Kenblue is still used legitimately as a control variety in university trials, which is why the name keeps appearing in research you might read. And Park still turns up at around 20% in low-cost sunny utility mixes. Neither is a reason to plant either one on a lawn.
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