As a gardening and landscaping expert, I would not recommend hydroseeding over an existing lawn. While it may seem like a convenient solution, there are several reasons why starting over or implementing overseeding would be a better option.
Firstly, hydroseeding involves spraying a mixture of seed, mulch, fertilizer, and water onto the lawn. This mixture needs direct contact with the soil to establish proper root growth. If you hydroseed over an existing lawn, the seeds may not reach the soil and may struggle to germinate effectively. This can result in patchy germination and an uneven lawn.
Additionally, an existing lawn typically has established grass and weed growth. Hydroseeding over this can lead to competition between the new seeds and the existing grass and weeds. This competition can hinder the growth and establishment of the newly seeded lawn.
In contrast, overseeding involves power raking the existing lawn to remove thatch and create small furrows in the soil. This process helps to expose the soil and create an ideal environment for the new seeds to germinate. After power raking, the seeds are broadcasted evenly over the lawn, ensuring better seed-to-soil contact. This method allows for better seed germination and establishment, resulting in a thicker and healthier lawn.
I have personally experienced the difference between hydroseeding and overseeding. In the past, I tried hydroseeding over an existing lawn, hoping for a quick and easy fix. However, the results were disappointing, with patchy areas and limited grass growth. I later learned about overseeding and decided to give it a try. The difference was remarkable, as the new seeds had direct contact with the soil and were able to establish themselves more effectively.
To summarize, hydroseeding over an existing lawn is not ideal due to poor seed-to-soil contact and competition with established grass and weeds. It is better to start over from scratch or implement overseeding to achieve a healthier and more uniform lawn.
