Using Compost as Mulch for a Healthy & Thriving Garden

Have you ever thought about using compost as mulch? In the world of gardening, compost is hailed as the “black gold” for its incredible benefits to soil health and plant growth. But did you know that compost can also serve as an excellent mulch? In a no-dig or no-till garden, this is actually standard practice and there is no reason you can’t adopt this practice either.

Using compost as mulch not only helps to retain moisture and suppress weeds but also enriches the soil with essential nutrients.

In this article, we will explore the many advantages of using compost as mulch and discover how this organic powerhouse can transform your garden into a flourishing oasis.

An asparagus bed with fresh, green spears growing in compost mulch.

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Using Compost As Mulch Is Not New

Compost has long been a staple in the world of no-dig, no-till gardening as a valuable and versatile mulch.

When using compost as mulch, it is spread directly on top of the soil before planting and around perennial plants, forming a protective layer.

This layer helps retain moisture, suppress weeds, regulate soil temperature, and prevent soil erosion.

As the compost gradually breaks down, it enriches the soil with nutrients, enhances microbial activity, and improves overall soil health.

This natural approach to mulching promotes a thriving ecosystem and minimizes disturbance to the soil structure, aligning perfectly with the principles of no-dig, no-till gardening.

And did you know that no-dig pioneers like Charles Dowding (and MANY others) plant in 100% compost?

It’s true. But we’ll save that for another article. Our raised beds are 60% compost if you’re curious and we top-dressed with compost and then mulched with other materials too.

Compost Mulch In A No-Dig, No-Till Garden

In a No-Dig, No-Till Garden, compost mulch is a valuable practice for enhancing soil health and promoting plant growth.

Following the principles of this gardening method, compost mulch is applied as a thin layer, typically around 1 inch deep, over the garden beds. This layer of compost acts as a protective covering, helping to suppress weeds, regulate soil temperature, and retain moisture.

It gradually breaks down and integrates with the underlying soil, enriching it with organic matter and nutrients.

The compost mulch is typically applied once or twice a year. The exact frequency may vary depending on factors such as the quality of the compost, the specific needs of the plants, and the overall condition of the soil.

The best compost is a mixed variety from many sources.

A wheelbarrow full of compost on a green lawn.

What Is The Best Compost To Use For Mulch?

The best compost to use for mulch in any type of garden is a well-balanced mixture derived from various organic sources.

A combination of compost from animal manure, mushroom compost, kitchen scraps, and other plant-based materials can provide a diverse range of nutrients and beneficial microorganisms.

It is important to ensure that the compost used does not contain any weed killer or herbicides, as these chemicals can negatively impact the garden ecosystem. And it is vital that the compost is well aged and well rotted, particularly animal manures.

By using a mixed variety of compost from different sources, gardeners can maximize the nutrient contents.

We obtain compost from several sources that we make right here on the homestead: the waste from our chicken coop (we use the deep litter system which you should seriously consider if you raise any poultry), the bedding from our Icelandic sheep, kitchen scraps, and mushroom compost from a nearby farm.

Other things like some leaves, grass clippings, small branches find there way in as well.

How To Apply Compost As Mulch (Step-ByStep)

  1. Prepare the garden bed: Ensure the garden bed is free from weeds, debris, and any existing vegetation. Clear the area to create a clean, empty bed.
  2. Prepare the compost: If necessary, sift the compost to remove any large chunks or uncomposted materials, ensuring a consistent texture for the mulch.
  3. Measure the compost: Determine the amount of compost needed to achieve a 1-inch layer of mulch. Measure the coverage area of the bed and calculate the quantity accordingly.
  4. Apply the compost: Spread the compost evenly across the empty garden bed, aiming for a uniform layer of approximately 1 inch. Use a rake or garden fork to distribute the compost and create an even surface.
  5. Smooth and level: Rake the compost gently to smooth and level the mulch layer, ensuring it covers the entire empty bed uniformly.
  6. Do not till: remember that this compost is a mulch and should not be tilled into the soil underneath.
  7. Plant your seeds or transplants (if applicable): Once the compost mulch is applied, it’s time to plant your seeds or transplants in the empty bed. Gently push seeds into the compost layer at the recommended depth, following the specific instructions for each plant variety. For transplants, create holes in the compost mulch and carefully place them, ensuring the roots are covered and the plants are properly spaced.
  8. Water the newly planted area: After planting, give your seeds or transplants a good watering to help them establish in the compost-enriched soil. Water gently and thoroughly, ensuring the moisture reaches the plant roots.
  9. Add other mulches: you may want to keep adding organic mulches onto your garden beds — we do.
  10. Monitor and care for your plants: Keep a close eye on your newly planted seeds or transplants. Regularly check the moisture level of the soil and adjust watering as needed to ensure optimal growth. The compost mulch will help retain moisture and provide essential nutrients to support healthy plant development.
A bean sprouting in a raised garden bed full of compost and compost as mulch.

When To Apply 

Compost can be applied as mulch during both spring and fall seasons, or even during both for optimal results.

In the spring, applying compost as mulch helps to nourish the soil and provide a nutrient boost to plants as they enter their active growth phase. It aids in retaining soil moisture and suppressing weed growth.

In the fall, applying compost as mulch helps to protect the soil and plant roots from harsh winter conditions, while slowly releasing nutrients into the soil.

By applying compost as mulch during both seasons, you can maximize its benefits and support the long-term health and productivity of your garden.

In poor soils, err on the side of caution and apply twice.

How Much Compost Mulch?

An inch is more than enough in healthy undisturbed soil.

In poor soil or newly established beds?

In a garden where tilling and digging is still practiced?

You can go as high as 4 inches, but no more is recommended.

Should You Mulch On Top Of Compost Mulch?

When using compost as mulch, there is generally no need to add additional mulch on top. Compost itself serves as an excellent mulch material, providing a protective layer for the soil.

However, if desired, you can layer other organic mulch materials on top of the compost to enhance its effectiveness.

We do!

We add chopped straw, grass clippings, other organic materials as they come by into our vegetable garden and strawberry beds.

Different mulch materials, such as straw, hay, wood chips, or shredded leaves, can be added on top of the compost to further conserve moisture, suppress weed growth, and regulate soil temperature.

This additional layer of mulch helps to create a more diverse and resilient garden ecosystem.

When applying multiple mulch layers, it is important to keep the total depth within a reasonable range, typically around 2 to 4 inches.

Avoid excessive mulch depths, as it can hinder water penetration and air circulation, potentially causing issues for plant roots.

In summary, while compost alone can serve as an effective mulch, incorporating different mulch materials on top can provide additional benefits.

Just ensure that the overall mulch depth remains appropriate for optimal plant health and garden performance.

A pallet-bin used for garden compost.

What Makes Compost Different From Other Mulch Materials?

Compost differs from other mulch materials in several ways.

Firstly, it is composed of decomposed organic materials, such as plant matter and yard waste, providing a rich source of nutrients for plants.

Secondly, compost has excellent moisture retention properties, helping to keep the soil moist and reducing water loss.

Additionally, compost improves soil structure, porosity, and drainage, creating an optimal environment for root growth.

Lastly, compost is teeming with beneficial microorganisms that support nutrient cycling and overall soil health.

These unique qualities make compost stand out as a superior mulch material, offering numerous benefits for plant growth and soil fertility.

How Long Does Compost Last As Mulch?

Compost used as mulch typically lasts several months to a year or more, depending on factors like compost composition and environmental conditions.

It gradually breaks down and incorporates into the soil, providing ongoing benefits.

The decomposition rate varies with moisture, temperature, and soil microbial activity. To maintain a consistent mulch layer, periodically replenish with fresh compost as needed.

Is Compost The Best Mulch?

Compost is widely regarded as one of the very best mulch options available, and for many gardeners, it can be considered the absolute best.

Its numerous benefits, such as improving soil health, providing nutrients, retaining moisture, and suppressing weeds, make it a highly valuable mulching material.

Additionally, compost’s ability to support beneficial soil organisms and promote long-term soil fertility further enhances its status as an excellent choice for mulching.

Pros & Cons Of Compost As Mulch

Advantages of compost as mulch:

  1. Soil enrichment: Compost enriches the soil with organic matter, nutrients, and beneficial microorganisms, improving soil fertility and overall plant health.
  2. Moisture retention: Compost acts as a natural sponge, helping to retain moisture in the soil and reducing the need for frequent watering.
  3. Weed suppression: A layer of compost mulch can help suppress weed growth by blocking sunlight and inhibiting weed seed germination.
  4. Temperature regulation: Compost mulch helps moderate soil temperature, protecting plant roots from extreme heat or cold.
  5. Erosion prevention: The layer of compost acts as a protective barrier, preventing soil erosion caused by wind or water runoff.

Disadvantages of compost as mulch:

  1. Nutrient competition: In some cases, compost mulch may compete with plants for nitrogen during the decomposition process. However, this is usually not a significant concern if the compost is well-aged and applied correctly.
  2. Cost and availability: Compost may require financial investment or effort to produce or purchase, depending on availability in your area.
  3. Appearance: Compost mulch may have a less uniform or aesthetically pleasing appearance compared to other types of mulch. However, this is a subjective consideration and may not be a concern for all gardeners.

Overall, the advantages of using compost as mulch far outweigh any potential drawbacks, making it a highly beneficial choice for gardeners seeking to improve soil health and enhance plant growth.

A market garden row of green lettuce growing out of the ground and compost mulch.

Final Thoughts

Using compost as mulch offers numerous benefits for your garden: it enriches the soil with essential nutrients, improves soil structure, retains moisture, suppresses weeds, and promotes healthy plant growth. Compost, with its organic matter and beneficial microorganisms, acts as a natural and sustainable way to enhance the health of your garden ecosystem. Whether you’re growing organic vegetables in an annual garden or asparagus in a perennial system, flowers, or trees, incorporating compost as mulch can contribute to long-term soil fertility and overall garden success.

For all the information you need on mulching in your garden, check out my guide Benefits Of Mulch In Your Garden {Ultimate Guide To Mulching} for all the best resources and knowledge.

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