Can Mulching Your Lawn Provide Natural Fertilizer?

Turning organic materials like leaves, grass clippings, or compost into mulch allows it to slowly decompose and release nutrients into the soil. This provides a natural fertilizer for your lawn without the need for chemicals. Mulching improves soil health, retains moisture, and may suppress weeds. The key is choosing the right mulch and application techniques to feed your grass and keep your lawn green.

Mulching Your Lawn Provide Natural Fertilizer
Mulching Your Lawn Provide Natural Fertilizer

Fertilizing Your Lawn With Mulch

Mulching your lawn can be an excellent way to fertilize it naturally. Mulch breaks down over time, releasing nutrients into the soil that grass needs to stay green and healthy. Using mulch to fertilize has a number of benefits:

Pros of Fertilizing With Mulch

  • Organic – Mulch fertilizes lawns organically without the need for chemical fertilizers. This is better for the environment.
  • Improves soil – As mulch breaks down, it adds organic matter to the soil, improving texture and nutrients. This creates better growing conditions for grass.
  • Retains moisture – Mulch helps soil retain moisture, meaning you may not have to water as frequently.
  • Weed suppression – A thick layer of mulch can block sunlight from reaching weed seeds and prevent them from germinating.
  • Low cost – Purchasing mulch is typically cheaper than buying commercial fertilizers, especially if you have ready access to free mulch sources like tree trimmings.

Best Mulch Types for Fertilizing

The best mulches to use to fertilize your lawn include:

  • Compost mulch –
    Made from decayed organic matter, compost mulch provides an excellent slow-release nutrient boost. You can make your own easily.


  1. Provides a broad spectrum of macro and micronutrients
  2. Releases nutrients slowly over an extended period
  3. Improves soil structure and nutrient holding capacity
  4. Can be made for free by composting yard waste


  1. Can be labor intensive to make enough compost for large areas
  2. Needs to be fully finished/mature before applying or can tie up soil nitrogen
  3. Can contain weed seeds if not properly heated during composting
  • Grass clippings –
    Freshly cut grass clippings from mowing provide nitrogen as they decompose. Leave them on the lawn to fertilize.


  1. Convenient and free source of nitrogen and other nutrients
  2. Break down quickly to deliver nutrients faster
  3. Helps cycle nutrients already in the soil
  4. Adds organic matter to improve soil


  1. Can develop a matted layer if applied too thickly
  2. Should only be used from grass free of pesticides/weed killers
  3. Large volumes needed to fertilize entire lawn
  • Leaf mulch –
    Shredded leaves offer nutrients like potassium and calcium as they break down. May be better for flower beds than lawns.


  1. Easy free source of mulch from fallen leaves
  2. Provides nutrients like calcium, magnesium and potassium
  3. Helps suppress weed growth
  4. Improves soil texture as it breaks down


  1. Can take a long time to break down completely
  2. Possible source of weed seeds and pathogens
  3. Unshredded leaves can clump together and resist breakdown
  4. Excess salt content can damage some plants
  • Wood chips/bark –
    Take longer to decompose but provide organic matter. Avoid dyed varieties.


  1. Often available for free from tree services
  2. Helps conserve soil moisture and temperature
  3. Looks attractive as part of landscaping
  4. Provides long term improvement of soil tilth


  1. Very slow to breakdown and release nutrients
  2. Depletes soil nitrogen as it decomposes initially
  3. Can attract termites if against structures
  4. Some mulch varieties are dyed which is not ideal
  • Straw –
    Straw mulch breaks down quicker, providing faster nutrient release. Ensure it is weed-free.


  1. Inexpensive and widely available
  2. Decomposes quickly to release nutrients faster
  3. Light color reflects heat and keeps soil cool
  4. Adds organic matter and improves soil


  1. Not as nutrient rich as other mulch sources
  2. Can blow away easily or float during heavy rain
  3. Often contains weed seeds that can germinate
  4. Needs frequent reapplication to maintain depth

Avoid using black plastic sheeting or landscape fabric below mulch, as this prevents breakdown and nutrient release into the soil.

When to Apply Mulch Fertilizer

The best times to fertilize with mulch are:

  • Early spring – Apply a fresh layer to provide nutrients for spring growth.
  • Fall – Mulch in early fall fertilizes grass before winter dormancy.
  • After aerating – Mulching after punching holes in the lawn helps nutrients reach the soil.

Mulch can be applied anytime during the growing season, but early spring and fall help prepare grass for the most vigorous growth.

How to Apply Mulch Fertilizer

Follow these steps for fertilizing your lawn with mulch:

1. Mow the Lawn

Cut the grass shorter than usual – around 1-2 inches – so the mulch can more easily reach the soil.

2. Rake the Lawn

Use a stiff rake to remove any dead grass, leaves or debris that could impede mulch contact with soil.

3. Spread the Mulch

Apply a 2-4 inch layer of mulch evenly across the lawn. Use a rake to distribute and help work down to soil level.

4. Water the Mulch

Water thoroughly after applying to help it begin breaking down and releasing nutrients into the soil.

5. Reapply Mulch Annually

Additional thinner layers can be applied yearly as the mulch breaks down. Grass clippings can be left after regular mowing.

Tips for Fertilizing With Mulch

  • When using compost, choose mature compost that is dark and crumbly with no recognizable debris.
  • For quicker results, use more soluble mulches like grass clippings, straw or fresh compost. Woody mulches break down more slowly.
  • Mulch application works best after aerating, as this allows better mulch penetration and nutrient delivery to the roots.
  • Watering after mulching helps accelerate the breakdown process and carries nutrients down into the soil.
  • Too thick a mulch layer can become matted and prevent water and nutrients from reaching the soil. 2-3 inches is ideal.

So in summary, fertilizing your lawn with mulch is an excellent organic method to improve soil quality and provide vital nutrients to grass. Follow the best practices outlined here for a green, healthy lawn using natural mulch fertilizer.

What’s the best time of year to fertilize with mulch?

The best times are early spring to feed spring growth and early fall to prepare for winter. Mulch can be applied anytime during the growing season.

How often should I apply mulch as fertilizer?

Most experts recommend reapplying a thin layer of mulch each year as the previous layer decomposes. Grass clippings can be left after regular mowing.

How long does it take for mulch to breakdown and fertilize the lawn?

It depends on the mulch type. Grass clippings and straw break down in weeks to months. Leaf mulch takes 6 months to a year. Wood chips/bark can take 1-3 years to fully decompose.

Should I fertilize with mulch in addition to chemical fertilizer?

You can use mulch to supplement chemical fertilizer, especially if you want to improve soil structure and moisture retention. But mulch alone can provide a full range of macro and micronutrients.

Is mulching a good fertilizing method for all lawn types?

Yes, mulch fertilization works well for most lawn grasses including bluegrass, fescue, ryegrass, St. Augustine, centipedegrass and zoysia. Adjust mulch application for specific grass needs.

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