Quick Answer
Yes, it is possible to put too much grass seed when overseeding or establishing a new lawn. Applying more than the recommended seeding rate can lead to problems like overcrowding, increased disease pressure, and lack of nutrient availability. The ideal seeding rate depends on the grass type, seeding method, and site conditions. Following the recommended seeding rate for your specific situation will help avoid potential issues with overseeding.
What Happens If You Put Too Much Grass Seed?
Putting down too much grass seed can lead to the following problems:
Crowding and Competition
With excessive seeds planted in a given area, the emerging grass plants will be crowded and have increased competition for resources like sunlight, water, and nutrients. This intensified crowding and competition will result in weaker, less vigorous turf.
Many newly emerged grass plants may die off due to the struggle to establish. The plants that do survive will likely be thinner and sparsely grown together.
Increased Disease Pressure
The combination of overcrowded, stressed grass plants can make the new lawn much more prone to diseases. Diseases like brown patch, dollar spot, and pythium blight thrive under crowded conditions with lack of air movement.
Fungus and other pathogens spread rapidly in dense, overcrowded turf. This can lead to major disease outbreaks taking hold in the new lawn.
Nutrient Deficiency
With an overabundance of emerging grass plants in a given space, the available nutrient supply can quick become depleted. Important nutrients like nitrogen, phosphorus, and potassium that are needed for growth and survival will become limited.
This can starve the establishing turf of vital nutrients, preventing the grass plants from developing properly. Weak, nutrient-deficient turf is more vulnerable to stresses and failure.
Weak Establishment and Thin Growth
The combination of overcrowding, disease pressure, and nutrient deficiency can lead to poor establishment after seeding. Many of the emerging grass plants may die out, resulting in patchy, sparse growth.
The grass that does survive will grow in thinly without forming a dense, uniform lawn. Too much seed can essentially smother itself, while allowing fewer plants to properly establish.
Signs You Used Too Much Seed
Here are some signs that indicate too much grass seed was applied during seeding:
– Extremely thick, dense growth several weeks after seeding. Grass is crowded and compressed together.
– Development of disease problems like brown patch and pythium blight shortly after establishment.
– Grass plants look pale, yellow, or nitrogen deficient despite proper fertilization.
– Final lawn has thin, patchy coverage even several months after seeding.
– Grass plants are sparse and spread far apart, with areas of exposed soil.
– Significant thinning, die-off, or bare patches develop after initial emergence.
If you notice these warning signs after seeding, it likely indicates too high of a seeding rate was used. The new grass stand has become overcrowded and lacking in resources.
Seeding Rates for Common Cool-Season Grasses
Here are the recommended seeding rates for some common cool-season turfgrass types:
Kentucky Bluegrass
– Seeding rate: 2-3 lbs per 1000 sq ft
– Seeds/sq ft: 1.2 to 1.8 million seeds per 1000 sq ft
Kentucky bluegrass should be seeded at lower rates in northern climates to avoid overcrowding issues. Higher rates can be used in the warmer transition zone.
Tall Fescue
– Seeding rate: 6-8 lbs per 1000 sq ft
– Seeds/sq ft: 300,000 to 400,000 seeds per 1000 sq ft
Use a maximum of 8 lbs per 1000 sq ft in northern regions. Up to 10 lbs per 1000 sq ft may be used in warmer southern climates.
Perennial Ryegrass
– Seeding rate: 6-8 lbs per 1000 sq ft
– Seeds/sq ft: 350,000 to 450,000 seeds per 1000 sq ft
Avoid going above 8 lbs per 1000 sq ft to prevent potential overcrowding and disease problems.
Fine Fescue
– Seeding rate: 4-6 lbs per 1000 sq ft
– Seeds/sq ft: 600,000 to 750,000 seeds per 1000 sq ft
Use maximum 6 lbs per 1000 sq ft rate, as fine fescue is prone to crowding-related issues at higher densities.
Seeding Rates for Warm-Season Grasses
Here are typical seeding rate benchmarks for some common warm-season lawn grasses:
Bermudagrass
– Seeding rate: 1-2 lbs per 1000 sq ft
– Seeds/sq ft: 400,000 to 800,000 seeds per 1000 sq ft
Up to 3 lbs per 1000 sq ft may be used for newly established lawns. Avoid going higher.
Zoysiagrass
– Seeding rate: 2-3 lbs per 1000 sq ft
– Seeds/sq ft: 350,000 to 550,000 seeds per 1000 sq ft
3 lbs per 1000 sq ft is usually sufficient. Higher seeding rates are prone to overcrowding.
Centipedegrass
– Seeding rate: 1-1.5 lbs per 1000 sq ft
– Seeds/sq ft: 150,000 to 400,000 seeds per 1000 sq ft
Never exceed 1.5 lbs per 1000 sq ft with centipedegrass seed. It establishes easily and is prone to overseeding issues.
St. Augustinegrass
– Seeding rate: 2-4 lbs per 1000 sq ft
– Seeds/sq ft: 175,000 to 350,000 seeds per 1000 sq ft
4 lbs per 1000 sq ft is the maximum recommended rate when seeding St. Augustinegrass.
Overseeding Rates for Existing Lawns
When overseeding into an existing lawn, some general seeding rate benchmarks include:
– Kentucky bluegrass: 1-2 lbs per 1000 sq ft
– Tall fescue: 5-8 lbs per 1000 sq ft
– Perennial ryegrass: 6-8 lbs per 1000 sq ft
– Fine fescue: 3-4 lbs per 1000 sq ft
– Bermudagrass: 0.5-1 lb per 1000 sq ft
– Zoysiagrass: 1-2 lbs per 1000 sq ft
Always stick to the lower end of the recommended rate ranges when overseeding to avoid problems. It’s better to reseed again later than apply excessive amounts upfront.
Factors That Increase Seeding Rate Needs
In certain situations, you may need to use seeding rates higher than the standard recommendations:
– New lawn establishment – Increase by 1-2 lbs per 1000 sq ft
– Broadcasting/drop seeding – Increase by 1-2 lbs per 1000 sq ft
– Poor soil or growing conditions – Increase by 1-2 lbs per 1000 sq ft
– Frequent foot traffic – Increase by 1-2 lbs per 1000 sq ft
– Overseeding into thick, dense lawn – Increase by 1-2 lbs per 1000 sq ft
– Warm season grass seeded in spring – Increase by 1 lb per 1000 sq ft
– Seeding cultivars with limited seed count per lb – Increase by 1-2 lbs per 1000 sq ft
While an increase from the standard rate is sometimes warranted, never double or triple the normal recommendations. Stick to slight incremental increases only to prevent serious overseeding issues.
Tips to Avoid Using Excessive Seed
Here are some tips to avoid applying too much grass seed:
Know Your Seeding Rates
Refer to the seed label, University resources, or professional guidelines to determine the right rate for your species and situation. Do not guess – excessive seeding usually results from not knowing correct rates.
Measure Properly
Carefully measure out the seed using a scale or measuring cup to ensure you apply only the target amount. Estimating or eyeballing seed quantities often leads to overapplication.
Seed Separate Varieties
If seeding a blend, apply tall fescue and bluegrass in separate operations. This allows proper seed placement for optimal germination.
Increase Passes, Not Rates
Making more seeding passes at lower rates ensures even coverage without overapplying. Putting down a heavy rate in one pass often dumps too much seed.
Focus on Good Soil
Improve soil conditions with aeration, amendments, proper pH, and fertilization before seeding. Good soils reduce the need for boosted seed amounts.
Allow Time
Be patient and allow at least 2-3 weeks after seeding before reseeding again. Prematurely applying more seed can compound problems.
Applying extra seed may seem helpful, but almost always causes more trouble than it’s worth. Stick closely to recommended rates and resist the urge to use more than required.
Effects of Using 50% More Seed
As an example, let’s examine the effects of using 50% more seed than recommended:
– Kentucky bluegrass – Increase from 2 lbs to 3 lbs per 1000 sq ft
– Tall fescue – Increase from 6 lbs to 9 lbs per 1000 sq ft
– Perennial ryegrass – Increase from 6 lbs to 9 lbs per 1000 sq ft
– Bermudagrass – Increase from 1 lb to 1.5 lbs per 1000 sq ft
At 50% over the normal rate, the emerging grass will become extremely crowded and compressed together. Diseases like brown patch and Pythium blight will likely develop shortly after emergence.
The overabundance of seedlings will rapidly deplete soil nitrogen levels, causing nutrient deficiency. Significant thinning will occur, with the final lawn growing in thinly.
Overall, a 50% overage in seeding rate will result in weak turf with poor density, disease problems, and inefficient use of expensive grass seed.
Correcting an Over-Seeded Lawn
Here are some tips for correcting and managing a lawn that has been over-seeded:
– Mow frequently at lowest height to remove excess growth and improve airflow.
– Apply preventative fungicide treatments to reduce disease pressure.
– Use soil tests and targeted fertilization to correct any nutrient deficiencies.
– Overseed thin, bare areas at 50% of normal rate if needed after thinning occurs.
– Aerate compacted areas to reduce crowding and competition between plants.
– Consider sodding severely damaged areas, rather than continuing to seed.
– Adjust seeding rates appropriately for any future overseeding or renovation needs.
While over-seeding issues can be challenging, the lawn should recover over time with proper maintenance practices. Be sure to adjust seed quantities appropriately going forward.
Key Takeaways
– Excessive seeding rates lead to crowding, disease problems, and nutrient deficiencies.
– Carefully follow recommended rates for the grass species and seeding situation.
– Measuring seed quantities, making multiple passes, and improving soils are key to avoiding overapplication.
– Increase rates incrementally only when necessitated by site-specific conditions.
– Problems from over-seeding can be corrected through cultural practices like mowing, fertilization, aeration, and overseeding bare areas.
– Heavily damaged lawns may need replacement with sod rather than trying to continue seeding.
Conclusion
Applying too much grass seed is an easy mistake to make when trying to achieve a nice, thick lawn. However, more is not always better when it comes to grass seed. Sticking closely to the recommended seeding rates for your specific species and situation will help avoid the pitfalls of over-seeding. A properly seeded lawn will establish thick, vigorous turf without the stresses of overcrowding and limited resources. With mindful planning and preparation, you can get the beautiful lawn you want without going overboard on the grass seed.
