Question:
Can I overseed my lawn "naturally" by letting it go to seed?Answer:
When the lawn is allowed to grow tall, it can produce seed heads. It stands to reason that if the seed heads are allowed to mature, the seed can fall to the ground, germinate, and grow, effectively overseeding the lawn and promoting a thicker stand of turfgrass in a "natural" way. In reality, this does not work. When grass is allowed to go to seed, it creates a thinner stand of grass that is less healthy and more prone to weeds.
Turfgrasses in the lawn get thicker primarily by spreading using above or below-ground runners or stolons. If the grass is allowed to go to seed, energy is diverted away from spreading and towards flower and seed production. This causes the stand of grass to become less dense because it is not growing and spreading. Additionally, the tall height of the grass when it produces a seed head will shade out parts of the lower canopy, further thinning the stand of grass. A thin stand of grass is more prone to weed issues because there is more bare soil and less competition, allowing weed seeds to germinate and grow.
Most modern turfgrasses are hybrids and produce sterile seed. So even if the seed could mature, drop off, and find its way down to the soil where it makes good contact to allow for moisture absorption, which is necessary to start the germination process, and receives regular rainfall to support seed growth (all highly unlikely), the seed produced is inviable and frequently sterile and therefore will never germinate.
It's best to purchase fresh, viable seed and overseed in the late summer or early fall to thicken a stand of turfgrass. Learn more about overseeding in this article: Overseeding a Lawn.
