One of the main factors that go into establishing a dense, healthy lawn is the amount of grass seed that you plant. More often than not, homeowners end up putting down too much grass seed, and the result is usually disastrous.
When you plant grass at the correct seeding rate, your turfgrass grows evenly, develops the appropriate structure, and becomes more resistant to pests and diseases. Additionally, you don’t have to wait too long for the lawn to be established, as grass seed germinates quickly when you apply the correct seeding rate. To determine the proper seeding rate, consider the size of your lawn, the type of turfgrass, and the soil conditions.
How much grass seed do I need?
It’s important to know how much grass seed you need. When you plant too much grass seed, the grass seeds will be crowded and compete for resources, resulting in slow germination and increased vulnerability to pests and diseases. Meanwhile, when you plant insufficient grass seed, you’ll end up with uneven growth and patches in the lawn. Additionally, understanding the right amount of grass seed required to cover your entire lawn helps you save money. You won’t end up buying more grass seed than necessary.
According to the United States Department of Agriculture (USDA), the seeding rate is the predetermined number of live seeds required per square foot to achieve a specific plant density. The main factors that affect the seeding rate of grass seed include:
- The type of seeding project (new lawn or overseeding)
- The time of sowing
- The sowing conditions
- The germination percentage
The appropriate seeding rate is mainly determined by whether you’re establishing a new lawn or overseeding. When establishing a new turf, the proper seeding rate is 4-7 lbs of seed for every 1000 square feet, translating to 10-12 seeds for every square inch of soil. Meanwhile, if you’re overseeding, a seeding rate of 1.5-4 lbs per 1000 square feet is recommended, depending on the type of turf grass.
Planting the right amount of grass seed is important for lawn health and aesthetics. Ideally, you want turf with a full canopy, which looks good visually and impedes weed growth. If you plant at a higher or lower seeding rate than recommended, your turf will be uneven, there’ll be patches on the lawn, and the exposed parts will lead to dry/compacted soil.
Can you overseed too much?
When you put down too much grass seed during the establishment of a new lawn or during overseeding, there’ll be various negative implications, including:
- Competition for soil resources (water and nutrients)
- Weak and shallow root systems
- Increased susceptibility to pests and diseases
- Poor grass structure
- Reduced germination rate
Competition for nutrients
Putting down too much grass seed has negative implications for turfgrasses, whether it’s a new lawn or an existing one (when overseeding). Grass roots require adequate space to grow deeper into the soil to access nutrients. When you exceed the recommended seeding limit, young grass seedlings’ crowded roots start competing for important resources like water and soil nutrients.
Weak and shallow root systems
The overcrowding impedes root growth, causing weak and shallow root systems. Consequently, the grass seedlings suffer stunted, patchy growth and may fail to develop the desired lush green shade.
Increased susceptibility to pests and diseases
Additionally, when you seed too heavily, your lawn becomes more susceptible to pests and diseases. As crowded grass seedlings compete for access to sunlight, they cannot generate sufficient energy via photosynthesis. Thus, their natural resistance to pests and diseases diminishes.
Poor grass structure
The surviving grass seedlings will suffer from highly competitive soil conditions and develop a poor structure. Due to insufficient nutrients, the grass blades and stems become thinly shaped. As a result, the grass becomes more vulnerable to damage from foot traffic and dieback due to harsh weather conditions.
Slower germination rate
When your grass seeding rate is too heavy, the seed germination rate reduces due to the high competition for access to the soil. Proper soil contact is required for germination to occur. The seeds that manage to reach the soil are usually impeded by the ones that don’t.
When you plant at the recommended seeding rate, your grass seeds should be able to germinate within 1-3 weeks. However, the germination period will likely be longer when you put down too much grass seed.
Ways to determine how much grass seed is needed + what constitutes too much grass seed?
To determine how much grass seed is needed for your lawn, consider the size of the lawn. The correct method for calculating the size of your yard is detailed in the next section. Additionally, consider the turfgrass type, as each has distinctive growth habits and prefers different soil conditions to flourish.
Finally, you need to understand the soil conditions. Test the soil pH and nutrient levels and make the necessary amendments to ensure proper grass seed growth. If you plant too much grass seed in nutrient-deficient soil, the grass won’t thrive.
Grass seed coverage
As mentioned earlier, you generally need to plant 10-12 grass seeds per square inch of soil for proper grass seed coverage. However, note that different grass species usually have different recommended seeding rates. Typically, you’ll find the recommended seeding rate included on the labeling of the bag/packaging.
Calculate the lawn size to determine the total amount of grass seeds you need for the entire lawn. Multiply the length of the yard by its width to find its area. Then, deduct the size(s) of the non-lawn areas that overlap with the lawn, such as the patio or the deck.
The final figure is the net square footage of your lawn. Convert this figure into square inches and multiply the result by 10 or 12. Alternatively, you can multiply the total size by the recommended seeding rate included in the packaging.
Once you implement the proper seeding rate by following the process detailed above, you’ll be able to enjoy a lush green lawn soon enough, as the grass seed will germinate faster. There’ll be enough soil resources; thus, your grass won’t thin out or develop patches. Moreover, your turf will be more resistant to pests and diseases and develop the proper physical structure to withstand foot traffic and harsh environmental conditions.
Always apply the proper grass seed coverage for a lush, healthy lawn with a dense canopy. Avoid putting down too much grass seed, as your turfgrass will struggle healthwise and aesthetically. Finally, ensure you use the proper methods to calculate the size of your lawn accurately and, consequently, the required amount of grass seed.
What is the proper seeding rate for overseeding?
As a general rule of thumb, when overseeding, you should plant about half the grass seed you would plant when establishing a lawn from scratch.
Does growth habit affect grass seeding rate?
Grasses that spread via rhizomes and stolons achieve a dense canopy faster and cover bare patches quickly; thus, you can lower the seeding rate. On the contrary, you’ll require a higher seeding rate for bunch-type grasses to achieve a full, dense lawn.
I. Morris J. Houck- the United States Department of Agriculture (USDA): Understanding Seding Rates, Recommended Planting Rates, and Pure Live Seed (PLS)