Accurately calculating the amount of material needed is the foundation for any successful grass planting project. Whether you are starting a new lawn from seed, filling in bare patches with plugs, or installing an instant turf with sod, determining the correct quantity prevents both costly waste and the frustration of thin, patchy coverage. This guidance ensures you purchase the right amount of seed, sod, or plugs to achieve a dense, uniform, and healthy lawn from the start.
Measuring Your Planting Surface
The first step in any planting project is to determine the total square footage of the area you intend to cover. For simple, rectangular spaces, this calculation is straightforward: multiply the length of the area by its width to get the total square feet.
Irregularly shaped lawns require a different approach, which involves dividing the space into a series of smaller geometric shapes, such as rectangles, squares, and triangles. Calculate the area of each smaller shape individually, and then sum the results to find the total square footage of the lawn. Subtract any non-planting areas from the final total, including patios, walkways, garden beds, or fixed structures.
Determining Seed Quantity for New Lawns and Overseeding
Grass seed application rates vary significantly depending on the species and whether you are establishing a new lawn or thickening an existing one. This variation is due to differences in seed size, germination rate, and the plant’s natural spreading ability. Application rates are standardized by weight, typically measured in pounds per 1,000 square feet.
New Lawn Installation
Starting a new lawn requires the highest application rate to achieve a dense stand of turf quickly. Cool-season grasses, like Tall Fescue, often require 8 to 10 pounds of seed for every 1,000 square feet of bare soil. Perennial Ryegrass is typically applied at a slightly higher rate of 10 pounds per 1,000 square feet. Smaller-seeded grasses like Kentucky Bluegrass are planted at a lighter rate, closer to 2 to 4 pounds per 1,000 square feet, because these plants spread laterally through underground rhizomes.
Warm-season grasses also follow specific planting guidelines. Bermuda grass is generally seeded at a rate of 2 to 4 pounds per 1,000 square feet when starting a new lawn. Zoysia grass requires a similar light application of approximately 1 to 2 pounds per 1,000 square feet. Once you have identified the correct rate for your chosen species, multiply your total square footage by this rate, then divide by 1,000 to determine the final weight of seed needed.
Overseeding/Repair
Overseeding an existing lawn requires a significantly lower seed quantity, generally about one-half to one-third of the rate for a new lawn. The goal is to introduce new plants to fill in thinning areas without causing excessive competition for nutrients and light among the seedlings. For instance, while Tall Fescue is planted at 8 to 10 pounds per 1,000 square feet for a new lawn, the overseeding rate drops to about 4 to 5 pounds per 1,000 square feet.
The overseeding rate for Kentucky Bluegrass is reduced to around 1 to 2 pounds per 1,000 square feet. For warm-season grasses like Bermuda, the recommendation is often 1 pound of seed per 1,000 square feet. Using too much seed during overseeding can lead to overcrowding, which produces weak, spindly grass plants that are more susceptible to disease.
Calculating Requirements for Sod and Grass Plugs
When opting for an instant lawn using sod or a gradual approach using grass plugs, the calculation method shifts from weight to area or count.
Sod is pre-grown grass that is sold by its actual square footage, either in individual rolls or on large pallets. A standard sod roll typically covers about 10 square feet, though this can vary by supplier. Pallets usually cover between 450 and 500 square feet, depending on the grass type. To calculate the amount needed, divide your total measured area by the coverage area of a single roll or pallet. It is common practice to order an additional 5% to 10% of the calculated total to account for trimming and fitting the sod around obstacles.
Grass plugs are small, rooted sections of turf that are planted at specific intervals to spread and fill in an area over time. The total number of plugs needed is determined by the required spacing between them. For a quick establishment, plugs are often spaced 6 inches apart, which requires a multiplier of 4.00 plugs per square foot. If you choose a wider spacing of 12 inches on center, the required quantity is reduced to approximately 1.00 plug per square foot. To find the total count, multiply your total square footage by the corresponding spacing multiplier.