Kentucky Bluegrass

The fastest-healing Kentucky bluegrass — the group that closes a bare patch on its own instead of waiting for you to overseed.

Best For: A lawn that takes real punishment: children, a dog that runs the same line every day, a worn strip by the gate, a patch of soil where the goal used to be. Full sun, in the north, on a yard you are willing to feed.

Tradeoff: It takes over. Put it in a blend and it crowds out the other cultivars, so whatever weakness it happens to carry becomes the whole lawn's weakness.

The original, unimproved Kentucky bluegrass — upright, pale and full of seedheads by late spring, which is how you spot it.

Best For: Anyone whose bluegrass looks thin, stemmy and seedy while a neighbour's looks dense and dark, and anyone standing in front of a shelf about to buy the cheapest bag of Kentucky bluegrass in the store.

Tradeoff: It has essentially no leaf spot resistance, so it thins itself out every cool, wet spring. That one weakness is the reason the entire improved bluegrass market exists.

The bluegrass for a lawn with tree shade or a watering restriction — the only group bred to resist the disease that shade brings.

Best For: A lawn getting 4 to 6 hours of direct sun rather than full exposure — a north-facing yard, or one with a couple of mature trees. It also suits a fully sunny lawn where watering is limited by cost, a well, or municipal restrictions.

Tradeoff: The best shade tolerance in the species is still only moderate — under a real closed tree canopy you need fine fescue, not this.

The darkest, densest Kentucky bluegrass there is — and the one that only looks that way if you keep watering it.

Best For: A full-sun front lawn in the northern half of bluegrass country where appearance is the point and an irrigation system is already in the ground. It suits someone who mows at 1.5 to 2.5 inches, feeds on schedule, and waters through July and August.

Tradeoff: The color is tied to the water bill — this is the group that loses its looks first when you stop irrigating.

The deepest-rooted Kentucky bluegrass — the group to plant if you want one bluegrass lawn that survives a hot summer without much fuss.

Best For: An ordinary sunny lawn anywhere in bluegrass country, and the first choice at the hot southern edge of the range where July, not January, is what kills the grass. It also suits anyone watering on a restriction or paying for every gallon.

Tradeoff: A medium-to-wide blade and a medium green — it will never look like the dark, fine showpiece next door, and the two cultivars that made this group's reputation have left the shelf.