A green lawn begins underground. Great soil has a big impact on the vigor and health of your turf. Topdressing works to improve both soil structure and fertility for a greener, more robust lawn.
This simple, chemical-free lawn practice involves spreading a thin layer of topsoil or compost over the turf. The topsoil or compost filters through the grass blades and rests on the soil surface, where it slowly breaks down and leaches into the soil, delivering valuable nutrients and improving the soil structure in the process. Topdressing can also be used to smooth a bumpy lawn; the new soil will fill dips and swales. Here are 14 tips to topdress your turf correctly.
1. Wait for the Active Growing Season
Spread topdressing when the lawn is actively growing. The grass will quickly grow through the material, and there is less of a chance that the layer of new soil will suffocate the turf. Spring and early fall are the best times to topdress lawns in cool regions, while early summer is best in warm regions.
2. Use Quality Topdressing Material
Topsoil and compost are the best topdressing materials for a home lawn. The product should be free of clods and rocks that will impede even spreading. If you are ordering topsoil or compost from a supplier, ask to view it before purchase. It should be crumbly and easily filter through your fingers when you pick up a handful.
3. Fix Compacted Soil First
Topdressing will improve compacted soil, but results come much faster if you aerate the lawn first. Rent a core aerator to reduce compaction by removing small cores of soil that will then open channels for soil, oxygen, and nutrients to penetrate the soil. After aerating, topdress the turf.
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4. Topdress to Improve Sandy Soil
Excessively sandy soil lacks nutrients and the ability to hold water. Topdressing delivers nutrients right to the turf’s root zone and soil particles amp up sandy soil’s ability to hold water.
5. Topdress to Improve Clay Soil
Clay soil is a good candidate for topdressing. While clay is high in nutrients, most of them are unavailable to plants because they are held tightly in the tiny clay particles. Topdressing provides nutrients to the lawn while slowly improving the structure of clay soil.
6. Use the Right Tools
Spread topdressing over large areas with the help of a drop spreader. Set the spreader opening to the largest particle size possible and make multiple passes to blanket the turf with about ½ inch of topsoil or compost. Topdress small areas by using a shovel to scatter the material. Whether you use a drop spreader or a shovel, be sure the material is dry for easy spreading.
7. Keep the Layer Thin
Err on the side of less when applying topdressing. Too much topsoil or compost smothers the existing turf. Aim to apply ½-inch or less of topdressing material. If the turfgrass is buried under too much topdressing, it will die due to a lack of sunlight.
8. Rake It In
Use a leaf rake to help the topdressing material filter through the grass blades to reach the soil surface. After spreading the product, gently rake the lawn. When the topdressing is in place, at least half the height of the leaf blades should be visible.
9. Be Ready for Weeds
Both compost and topsoil potentially introduce weed seeds into the turf. Be watchful for weeds in your lawn and eliminate them when they are young.
10. Pair Topdressing with Aeration
Topdressing and aeration are excellent lawn care partners. Aerating a lawn involves removing small cores of soil that are left on the soil surface. The holes in the turf that remain after aeration are excellent channels for topdressing material to filter into the soil profile.
11. Consider Overseeding
If your topdressing project involves filling swales and dips in the lawn that require more than ½ inch of soil or compost, or if your lawn is generally thin, it might be a good idea to overseed your turf right after you topdress. The topsoil or compost will make an ideal seedbed.
12. Understand the Limitations of Topdressing
No matter how much topdressing you apply or how precisely you spread it, it won't improve a grass cultivar that is simply unsuited for the location. The adage “right plant, right place” applies to turfgrass, too. Some grass types thrive in shade while others grow best in full sun. Know your grass and growing conditions before trying to “fix” a lawn problem with topdressing.
13. Topdress Annually
Apply topdressing yearly to maximize the benefits of this natural lawn care technique. It is especially beneficial for lawns growing in clay or sandy soil.
14. Be Patient
When topdressing for improved soil and growing conditions, as opposed to topdressing to smooth out an uneven lawn, expect to make multiple applications over several years to see improvement in lawn health. Lawns growing in clay or extremely sandy soil benefit greatly from topdressing when it is done annually for a decade or more.