The USDA produces a map that shows the US divided into 2 main grass growing zones and several subzones. The Cool/Humid zone covers most of the Northeast from the Great Lakes to New England and the California to Oregon shore areas. The Warm/Humid zone covers most of the SouthEastern US that doesn’t see frost.
In between there is a Transition zone that is a mix of both. There are also a Warm/Arid and Cool/Arid zones that we won’t cover here as growing turf grasses in the desert cannot be made easy. Some parts are cold enough in the Winter that warm weather grasses have difficulty, yet warm enough that cool weather grasses can’t survive.
Grass Growing Zones
In addition to climate zones, landscape planner may also look at the topsoil types. This is still a new science as mapping is complex and hasn’t been completed. It’s a task that until recently has been handled primarily as local knowledge by landscapers. Soil scientists have put together the Unified North American Soil Map, a compilation of grid surveys from across the country. There is a Google Earth overlay if you are interested.
The technical soil type is interesting, but for most of us, the important parts are how much organic content the soil has, its depth, consistency, and its drainage. Your agricultural extension service or local garden shop can probably give you a visual opinion, chemical elements like nutrient content and Ph may require a soil test. Good topsoil is usually dark brown or almost black. Lighter colors indicate an abundance of salt a lack of organic elements. Damp soil should form a loose and crumbly ball when squeezed in your hand. Your grass needs to grow roots in it. Too hard and roots (or water) won’t be able to penetrate. Too soft or sandy and water will drain away quickly. Muddy soil will still be muddy under your grass.
Different soil types may require different seed types. Or in some locations, your testing might determine that there isn’t a way to build an easy lawn.
Seed Selection by Zone
Turf breeders are constantly working to develop new and better strains for each zone, but it’s a slow and incremental process. There isn’t such thing as a “universal grass seed”. Some grow better in certain areas. Perhaps the best way to choose seed for your area is to web visit your state’s agricultural extension service. It’s usually associated with an agricultural college or university.
Another good way to choose seed for your zone is to check with the major seed houses. Many of the big national ones blend local mixtures for each zone and many subzones. Only trust the bigger companies that put their reputation at risk. Companies like Scotts, Pennington, or Ampac want you to come back often. No name or house brands may not be as trustworthy.