How to Naturally Feed Your Lawn by Topdressing with Compost- Gardening Expert and Host of Growing a Greener World®
August 14, 2021
A healthier lawn comes with healthier soil, and there is no better way to improve soil health than by adding compost.
Compost contains the primary nutrients — nitrogen, phosphorous, and potassium — and an array of micronutrients to naturally feed a lawn. But there are many other benefits as well.
Topdressing a lawn with compost adds organic matter to the soil, which provides for proper drainage and better tilth. That organic matter also hosts beneficial microorganisms that turn organic fertilizer and minerals in the soil into plant-available nutrients that can be taken up by roots.
You can topdress with compost at any time when the ground is not frozen, but if you topdress right after aerating a lawn, you will see even better results. Another great time to topdress with compost is when overseeding a lawn. Applying compost and seeds at the same time will improve germination and moisture retention.
Step 1: Determine How Much Compost You Need
When topdressing, you want to use enough compost to be effective but not so much that the compost smothers the grass. Aim to use between a quarter-inch and a half-inch layer of compost. For the maximum depth, that is one cubic foot of compost for every 25 square feet of lawn.
One cubic foot is a popular size for bagged compost, but bags can be smaller or larger. But no matter the bag size, when you find you need more than 10 bags of compost for a project, it generally makes more sense to buy bulk compost. Bulk compost is sold by the cubic yard, and there are 27 cubic feet in a cubic yard.
Step 2: Choose the Compost
Choose compost that was produced through a hot composting process, in which the heat given off by the biological activity of microbes reached more than 140°. The high temperature ensures that weed seeds and pathogens that were in the compost inputs have been neutralized. If you buy commercial compost or use municipal compost, you should be all set in that regard. If you plan to use your homemade compost, test the compost pile with a soil thermometer while it is still active.
You should see and touch the compost yourself before placing an order. It is free of rocks, glass, and plastic. Does it have that earthy smell? When you squeeze the compost in your hand, does it clump together well but also break apart easily? If the compost doesn’t pass these tests, don’t buy it.
Compost spread out on the lawn
Step 3: Distribute the Compost
Fill a wheelbarrow with bags or loose compost, and dot the lawn with small piles of compost, evenly distributed. The piles should be no larger than three or four shovelfuls each. The idea is to space the piles so that once the compost is spread out, the lawn has full coverage, with no gaps.
Step 4: Rake the Compost into the Lawn
You can spread the compost with just about any rake, but a metal rake with sturdy tines will work best to scratch up the soil surface and incorporate the compost. At each pile, rake the compost out in all directions, 360°. Rake until the point that the grass blades are almost fully visible through the compost.
Step 5: Water In
Water in the compost with a sprinkler. A gentle application of water will help the compost work its way down to the soil and will expose grass blades that are covered, so they won’t be smothered. It’s important not to apply a heavy amount of water over a short period of time because that should cause the compost to run off instead of staying where the lawn needs it.
Other Natural Nutrients to Feed Your Lawn
One of the best nutrient sources for the grass in your lawn is the grass itself. Recycling grass clippings can provide 25% of your lawn’s nutrient needs over the course of a year. It’s obvious when you think about it: Grass clippings contain the exact ratio of nutrients that grass requires. Plus, the clippings help the lawn retain moisture while shading out weed seeds, which keeps those seeds from germinating.
Recycling grass clippings is actually less labor-intensive than the alternative. While bagging and disposing of or composting grass clippings takes extra work, using a mulching mower means you don’t have to carry around and empty heavy bags of clippings. The clippings remain in place, exactly where they can be put to work feeding the lawn.
You may already be mulching your grass into the lawn, but did you know that you can also use a mulching mower on leaves? When leaves drop on the lawn in autumn, even an average mulching mower can chop them up to a size at which they will decompose quickly, feeding the lawn as they do. A thick layer of leaves will take quite a few passes with the lawnmower before the leaves are reduced to a size that disappears into the lawn, but if you mow frequently, falling leaves will be easier to manage. You’ll also save yourself a lot of work on raking!
When to Supplement with Fertilizer
Though adding compost and mulching grass clippings and leaves will reduce the need for supplemental fertilizer, these practices cannot completely replace fertilizer. A slow-release fertilizer like Milorganite will feed the lawn continuously for many weeks, with none of the nutrient-burn concerns that come with synthetic fertilizers.
Fertilizer will help the grass grow and will give the lawn that deep, emerald green color. The lawn will be denser, which withstands foot traffic and stops weeds from taking hold.
In northern regions, where cool-season grasses dominate, apply Milorganite once or twice between Labor Day and Thanksgiving, waiting 8-10 weeks between applications. Apply again, once or twice, between Memorial Day and the Fourth of July.
In southern regions, where warm-season grasses thrive, apply in the spring after the grass breaks its winter dormancy, and then again around Memorial Day. In the fall, apply once or twice between Labor Day and early October.