Aerating, thatching, seeding, fertilizing of Seattle area lawns. Would You Like a Beautiful, Healthy Lawn? Aerate, seed and fertilize in the Spring and Fall so you can have a lush, green, healthy lawn. Thatching- Thatch is a dense mat of roots, stems and grass clippings that accumulate between the soil and growing blades of grass. With thatch removed, air, water, nutrients, herbicides and pesticides can do their job. Turf becomes healthier and more resistant to insect damage and disease. Aerating- Aeration is the process of mechanically removing cores of turf to improve the flow of air, water and nutrients in dense, compacted soil. Soil compaction, caused by lawn traffic such as walking and mowing, is one of the greatest causes of turf deterioration. When soil is compacted, dirt particles are forced together, reducing the area where roots can grow. Aeration relieves soil compaction by improving the exchange of water and critical nutrients to grass roots.