Whether overseeding to fill bare spots or thickening an existing lawn, you need a seeding machine that creates excellent seed-to-soil contact. This differs from broadcast seeding, which works best on healthy lawns and doesn’t work well for bare areas.
Overseeders use blades to cut narrow furrows at adjustable depths and drop grass seed into them from hoppers. This helps to ensure the grass seeds are in direct contact with the soil, promoting successful germination.
In a professional spreader, a drive wheel turns a whirling impeller plate under the hopper that catches and throws the payload. A shutoff plate opens and closes to control the amount of dispersed product each time you push the grass seeding machine forward.
A spread rate gauge mounted on the handlebar lets you set the size of the hopper holes (according to the recommended setting found on many bags of lawn products), ensuring that an accurate volume of the product will uniformly exit the hopper.
For a seed to germinate, it must come into contact with soil. Thatch is a barrier to seed-to-soil contact and needs to be removed using a metal dethatcher or powered lawn scarifier with adjustable blades that cut through the grass and then scrape upward for easy removal.
Alternatively, you can use a power rake with steel tines to loosen the thatch and allow water and air to penetrate. Cultivating the soil is also required before overseeding to expose the grassroots and prevent weeds from taking root.
Seed Dispersal Rate
When overseeding a lawn, high-quality grass seed must be tamped into loosened soil and consistently kept moist until it germinates. A stiff rake and hose can work for small areas, but a power equipment rental shop may sell or rent a slice seeder for more extensive lawns.
These machines cut shallow slits (like miniature furrows) in the lawn and drop in the seed. The slits allow the seeds to get in direct contact with the soil and open pathways for water, fertilizer, and sun.
Slit seeding is usually done in late summer and early fall – when the weather and soil temperatures are typically most favorable for good seed germination. But it can also be done in spring and winter.
Seed Storage Capacity
When overseeding, you must know how much seed can be placed per pass. This will determine the amount of time required to complete the overseeding operation.
Grass seeds, like all crops, age rapidly in storage. This deterioration can have immediate and residual effects on the performance of the seed. The rate of deterioration varies among seed lots of the same kind and within individual seeds of each lot. The rate of deterioration is related to the pre-storage history of the seed.
The storage requirements of different kinds of grass and flower seeds vary. Generally, most seed types will remain viable for one year when stored at 9-11% moisture content and warehouse temperature not exceeding 650F.
When “carried over” conditioned storage is required, it is recommended that the seed be kept in a separate warehouse from fertilizer, chemicals, and herbicides. This will minimize contamination from insect infestations. During this period, the seed should be regularly inspected for deterioration.
Overseeding promotes healthy turf while repairing damage to existing lawns. This is particularly important when dealing with bare spots caused by heavy foot traffic, insects, or disease. Regular overseeding can strengthen grass to help crowd weeds, overtaking wispy lawns.
One popular method of seeding is called slit seeding (also known as slice seeding). This technique uses a machine to make slits in the soil that then drop seeds into them. This allows for direct seed-to-soil contact, which is vital to the germination process.
Another popular method is hydroseeding. This technique mixes seeds, mulch, fertilizer, and water into a mixture known as a slurry. It is then sprayed onto a growing surface where, within five to seven days, new grass begins to grow and sprout. A hydroseeding machine is particularly beneficial in steep slopes, as it helps control soil erosion and promotes a more stable landscape.