Grass clippings mixed in with soil act as a slow-decomposing fertilizer that feeds deep-rooted plants. To mix cut grass with soil, till the soil to a depth of 6–12 inches (15–30 cm) and mix 10 pounds of grass clippings into the soil for every 1,000 square feet. This will provide slightly under 1/2 pound of nitrogen to the soil. Grass clippings mixed into the soil may take 6–12 months to decompose. To encourage grass clippings to decompose faster, add them to your compost pile or use them as mulch instead of mixing them with soil.
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Can You Mix Grass Clippings Into Soil?
You can mix grass clippings into the soil to boost nutrient content in your yard or garden. Grass clippings contain 4% nitrogen, 1% phosphorus, and 2% potassium. This makes lawn clippings the equivalent of a 4-1-2 fertilizer. By mixing grass clippings into the soil, you provide a natural fertilizer. Mixing fresh grass clippings into your garden soil can be easily accomplished by using a tiller.
- Grass clippings mixed with soil act like a very slow release 4-1-2 fertilizer.
- A rototiller can be used to easily mix grass clippings into the top layer of your soil.
- Mixing grass clippings with soil causes them to break down more slowly than other methods.
It’s important to note that grass clippings decompose slowly when mixed with the soil. This is because grass clippings need exposure to oxygen in order to break down. When grass clippings are buried belowground they receive very little oxygen. It may take buried grass clippings as long as 1 year to fully decompose and release their nutrients into the soil. In comparison, other methods for using grass clippings as fertilizer work in weeks or months.
How to Mix Grass Clippings Into Soil
To use grass clippings as soil fertilizer, it’s important to incorporate the clippings into an area of loosened soil. Till the soil of the lawn or garden to a depth of 6–12 inches (15–30 cm). Then, spread 10 pounds of grass clippings for every 1,000 square feet. Finally, perform a second pass with the rototiller. This will mix the cut grass in with the soil.
- Use a rototiller to loosen the top 6–12 inches of soil.
- Spread 10 pounds of grass clippings for every 1,000 feet of tilled garden soil.
- Rake grass clippings to spread them evenly on top of the tilled area.
- Till the area again, mixing the grass clippings into the soil to the desired depth.
- In small garden plots, a shovel or rake can be used to turn loose soil instead of a tiller.
If you do not own a rototiller, you can rent one from your local hardware store. In small garden plots or bare portions of your yard, a shovel or garden rake can be used to loosen soil and mix grass clippings in at the desired depth.
How Long Does it Take Grass Clippings to Turn into Dirt?
Grass clippings decompose and release organic material slowly when buried. Grass clippings mixed with soil require 6–12 months to fully decompose. In comparison, grass clippings left on top of your lawn will break down in just a few weeks. If you want fast fertilizer from your lawn clippings, use fresh grass clippings as a top dressing or mulch.
- Grass clippings mixed with soil: Full decomposition in 6–12 months.
- Grass clippings used as mulch: Full decomposition in 2–3 months.
- Grass clippings in compost: Full decomposition in 1–3 months.
- Grass clippings left on top of lawn: Full decomposition in 3–4 weeks.
Mixing grass clippings into the soil is actually the slowest way to transform them into a natural fertilizer. Grass clippings will work faster as fertilizer when left on the lawn or spread on top of your garden soil. For this reason, it’s only a good idea to mix grass clippings with soil if you are specifically attempting to feed deep-rooted plants.
What is the Best Use of Grass Clippings?
Grass clippings are a natural source of organic materials that fuel plant growth. As it grows, grass pulls nitrogen, phosphorus, and potassium from the soil, along with iron and other natural compounds. These nutrients are used to form grass blades. So, cut grass is essentially an organic fertilizer waiting to be used. Those fresh clippings aren’t yard waste, they’re a source of plant fuel. The best ways to use grass clippings are:
- Leave them on your lawn to act as fertilizer.
- Lay a 3–4 inch layer of grass clippings as mulch in your garden.
- Add grass clippings to your compost pile as a source of nitrogen.
Each of these methods encourages grass clippings to break down quickly and release those natural nutrients so they can be used to fuel future plant growth. These methods also work faster and are usually less labor-intensive than mixing grass clippings into the soil.
Grass Clippings as Lawn Fertilizer
Grass clippings left on your lawn start to break down almost immediately. In 1 week, most grass clippings will no longer be visible. By week 2 or 3, the grass clippings may have broken down entirely. This provides an almost instant boost to your lawn by returning nutrients to the soil.
- Grass clippings left on the lawn will break down completely in 3–4 weeks.
- Do not bag grass clippings while mowing. Leave them where they lay to fertilize your grass.
- If grass clippings form clumps while mowing, rake them after mowing to separate them and speed up the decomposition process.
Although grass clippings on your lawn may seem unsightly, this problem can easily be remedied. Simply rake any areas of your lawn where grass clippings are visible. This helps to spread the grass clippings and work them down to the soil surface. Not only will they be out of sight, but they’ll also break down faster this way.
Use Grass Clippings as Mulch
Grass clippings make excellent mulch. Simply lay a 3–4 inch (7.5–10 cm) layer of cut grass in your garden. In order to ensure the grass clippings will decompose properly, allow them to dry on your lawn for 1–2 days before raking them up to use as mulch.
- Grass clipping mulch forms a weed-suppressing barrier in your garden.
- Lay 3–4 inches of dried grass clippings in your garden to stop weeds and insulate soil.
- Grass clipping mulch breaks down in 2–3 months.
Your grass-clipping mulch will decompose over time. In 2–3 months, that layer of mulch will return to the soil. This feeds your garden soil with nutrients, and can even help prevent future weeds. Simply replenish your vegetable garden with more grass clippings periodically to maintain your mulch layer year-round.
Add Grass Clippings to Compost
Grass clippings make an excellent “green” or nitrogen-rich component in compost. However, grass clippings are best used sparingly in compost. The ideal compost ratio is 30 parts “brown” or nitrogen-poor material to 1 part “green” material. This means that for 1 pound of grass clippings, you will need to add 30 pounds of dry leaves, wood chips, or other brown materials. If you add too many grass clippings, your compost will release terrible smelling ammonia gas.
- Add grass clippings to the compost to create nitrogen-rich natural fertilizer.
- Add 1 part grass clippings (by weight) for every 30 parts brown material (leaves, wood chips, etc.).
- Avoid adding too many grass clippings to compost. Doing so can create noxious ammonia gas as the grass clippings decompose.
As long as grass clippings are used in moderation, they make an excellent additive to compost heaps. The nitrogen-rich grass is necessary to cause the brown materials to break down and form the healthy compost fertilizer you can use to feed your garden.
Should You Mix Grass Clippings into Soil?
Grass clippings can be mixed into the soil using a tiller or with a shovel. However, doing so slows the decomposition of grass clippings. Deprived of oxygen underground, the grass may take up to 1 year to fully decompose and return its nutrients to the soil. This can be beneficial for creating rich soil at deep levels, where you plan to grow deep-rooted plants. However, if they are used as top dressing or mulch, grass clippings will break down much faster and feed the soil in a few weeks or months.