Topdressing turf is an old concept dating back to the old course at St. Andrews and Old Tom Morris, but has only recently been catching on among homeowners. The instant gratification, convenience, and profit involved with modern lawn care triumphed over the old art of manually spreading compost on the lawn. However, with the advent of organic lawn care, a new romance with topdressing is developing amongst America's homeowners.
What is topdressing?
Topdressing a lawn is the process of adding a thin layer of material over the lawn. Typically 1/4 inch - 1/2 inch of compost or other soil amendment is spread across the lawn with shovels, in a throwing action. The material can be worked into the thatch area by raking, washed in with rain or sprinklers, or allowed to settle on its own. It is labor intensive and may be a reason for its lack of popularity. Motorized topdressers and compost spreaders are available but are costly for a rarely used machine. Lawn care companies sometimes offer a topdressing service but it is often viewed as an inconvenience because of the materials and labor involved. As organic lawn care gains popularity, so too will the act of topdressing the lawn on a regular basis.
Topdressing's benefits are so numerous, it's hard to understand why it is not the foundation for every lawn care program on the planet. As a soil amendment, topdressing can improve soil biology by adding organic matter and the beneficial microorganisms of compost. Soil structure and drainage can be modified by topdressing with sand or other corrective materials. Topdressing regularly can smooth out bumps caused by worm castings and encourages a dense, lush lawn. Topdressing reduces lawn stresses, helps keep thatch under control and acts as a long term natural fertilizer. Adding organic matter to a lawn by topdressing with compost is the most beneficial cultural practice lawn care has to offer.
What is the best material for topdressing?
Topdressing materials vary greatly and are usually dictated by budget and need. Most topdressing is performed with compost which can vary in quality and get expensive. Compost should be made from the appropriate ratios or wet and dry materials and should be fully "cooked". High quality finished compost should be dark and rich and made with a variety of organic material with few fillers like sawdust or loam. In some cases, compost is blended with soil or sand to make it more affordable, just be sure the added soil is compatible with the soil of the lawn.
Buying topdressing material can be tricky, especially if the source is trying to save money not letting the compost cook long enough or by using too much filler and not enough finished compost - effectively selling the customer short. It is okay to have some organic material that has yet to break down in the topdressing mix but too much filler will negate the benefits of topdressing, making the results less noticeable and potentially discouraging future topdressing applications. Always buy compost from a reputable source.
Sand is sometimes used as a topdressing material on lawns with heavy, clay soils or drainage problems. Usually applied after aerating, the sand fills in the holes and over time can alter the sturcture of the soil to allow for better drainage and a healthier grass.
How to topdress
Topdressing can be quite labor intensive and at the very least requires shoveling and moving piles of compost or other topdressing materials. The hard work is worth it though and new machines are now available to save on much of the manual labor. Traditionally, topdressing is spread by the shovelful in a manner that I have always felt was similar to taking a shot with a hockey stick. A smooth, sweeping motion aimed at trying to spread the material as evenly as possible to a depth of 1/4 inch to 1/2 inch. Topdressing machines are also available and consist of a hopper to hold the material with a motorized belt to move the product through the hopper to a spinning disc which spreads it on the lawn. These machines are just beginning to get popular as more and more people request topdressing with compost as part of their lawn care regimen.
When topdressing, it is beneficial to do it in conjunction with other cultural practices like aerating, de-thatching and overseeding. Topdressing after aerating and overseeding is the ideal trio of lawn care chores that will result in a healthier lawn. The aerating opens up the soil, allowing for better air and water movement and reduced compaction. The aeration holes provide the perfect seed bed for overseeding, allowing newer generations of grass to establish and thrive. Lastly, topdressing with compost, helps fill in the holes, covering the seed and allowing for ideal germination conditions with a burst of nutrients as the seedlings establish. It's a win, win, win, situation.