How Much Grass Seed Is Needed for One Acre?

Types of Grass

• Horticulturists have separated grasses into warm season and cool season species. Each species has many varieties, accommodate different growing conditions, such as sandy soil, summer drought or extreme winter cold.

Soil Temperature

• Soil temperature affects the germination rate. If you are planting at a time that is not ideal for your type of seed, then adjust your calculations to account for a lower germination rate.

Warm Season Grasses

• To calculate how much seed you need for one acre of warm season grass, start with the Pure Live Seed (PLS) chart for the variety you are planting. Bags of warm season grass seed contain bulk material other than the live seed. The PLS chart tells you what percentage of the bag is actually pure live seed. For example, if the PLS on a 100-lb. sack is 85 percent, then you have 85 lbs. of actual grass seed for planting. You will find the chart printed right on the bag of grass seed. However, if you are ordering from the Internet, then the information should be readily available on the nursery's website.

Cool Season Grasses

• Cool season grasses grow during the spring, become dormant during the summer and then grow again during the autumn. For best germination, plant cool season grasses in early spring or early autumn, depending on the species, and when the soil temperature is above freezing but below 65 F. Calculate the amount of cool season grass needed by its seeding rate, designated as lbs. per acre, and whether it is all one variety (pure stand) or part of a mixture. For example, Orchardgrass has a seeding rate of 6 to 10 lbs.per acre when part of a mix but 10 to 15 lbs.per acre when pure, according to the Kentucky Department of Fish and Wildlife Resources.

Calculating Mixed Seed Requirements

• If you should decide to make your own custom mix of seeds, your local county extension office can provide seeding rates for different mixed grasses native to your region of the country.

Density

• Planting grass seed more densely than recommend requires an upward adjustment in your calculation. For example, if you decide to plant 40 lbs. per acre instead of the recommended 30 lbs., then you need 25 percent more grass seed.