Top Dressing & Seed What is Top Dressing? Top Dressing is the application of a mixture of sand and loam. We then spread a layer of seed and rake in. Why top dress & seed? 1. This can be particularly beneficial after aeration as it falls to the bottom of the holes. 2. It then creates a pocket that improves the drainage and that roots like to grow in. 3. It also helps with the levels on your lawn and is the ideal bed for new seed. 4. If required a kiln dried mix or Surrey loam can be obtained.