What Is the Difference Between Straight Grass Seed & Mixture or Blended Grass Seed?

Choosing the right grass seed product for your lawn can be challenging when you're faced with all the options for straight seed, mixtures and blends. Understanding the differences between these types of seed products can help you decide which one fits your lawn needs best.

Seed products that contain a single lawn grass variety or a single grass species -- without any named variety -- are known as straight or single-seed products. These types of products are often used to improve existing lawns. For example, straight Kentucky bluegrass (Poa pratensis) is a cool-season, northern grass species that normally does best in U.S. Department of Agriculture plant hardiness zones 2 through 6. This grass species can grow outside those zones, but it struggles with heat and drought.

Overseeding an existing Kentucky bluegrass lawn with a drought-tolerant cultivated variety, or cultivar, such as 'Mallard' Kentucky Bluegrass (Poa pratensis 'Mallard', USDA zones 3 through 8) increases diversity and improves the drought tolerance of the lawn as a whole. It also allows Kentucky bluegrass fans in warmer climates to enjoy this species. In the same way, you might choose a cultivar known for disease resistance to improve your lawn's resilience.

Seed products that combine more than one type or genus of grass or more than one species from the same genus is called a mixture. Seed mixes combine complementary, desirable grasses for a more pleasing lawn. A grass seed mix might include Kentucky bluegrass, perennial ryegrass (Lolium perenne, USDA zones 3 through 6) and creeping red fine fescue (Festuca rubra var. rubra, USDA zones 3 through 7). Perennial ryegrass greens up much faster in spring than Kentucky bluegrass, and creeping red fescue has better shade tolerance, but all three have similar textures. Planting a combination of these three types creates a more versatile, yet still attractive, lawn.

A product that includes two different species of the same grass type or genus is also known as a mixture. For example, a mixture of perennial ryegrass and annual ryegrass (Lolium multiflorum) might be used to overseed warm-season, southern lawn grasses that go brown and dormant over winter, such as Bermuda grass (Cynodon dactylon, USDA zones 7 through 10). The mixture of fast-germinating, cool-season ryegrass species gives southern lawns temporary green color until spring. Bermuda grass has invasive qualities in some locations.

When all the seed varieties in a seed product belong to the same species, the product is known as a seed blend. Combining various cultivated varieties of a single species benefits lawns in diversity and resilience. A blend of Kentucky bluegrass varieties, for example, might include grasses with different environmental and disease tolerances, so if harmful conditions strike the lawn, not all the varieties are vulnerable. A Bermuda grass blend for southern lawns might include different Bermuda grass varieties that offer better cold-tolerance, improved traffic tolerance or quicker green up in spring, but all within the Bermuda grass species.

All U.S. seed products have an attached label called a seed tag or certified analysis tag. This tag or label lists all the seed types and name varieties in the specific seed lot that's in that bag. The tag also reflects the tested germination rates of the seed and other information to help you choose the best seed for your project.