Why Should You Reuse Spent Mushroom Substrate?

Why Should You Reuse Spent Mushroom Substrate?

So you’ve grown your mushrooms and harvested them, but what do you do with the left over substrate?

Many people throw it away thinking it’s a disposable by-product of the growing process. But this nutrient-packed mix can have many uses that make it worth keeping.

In this guide we’ll explore the benefits of spent mushroom substrate and how you can reuse it in many creative ways. 

Ready to learn more? Keep reading!


What Is Spent Mushroom Substrate?

Spent mushroom substrate is the material used to grow mushrooms, left over after harvesting. Commonly made of straw, sawdust or compost, SMS also contains remnants of fungal biomass. Whilst some of its nutrients are used up during cultivation, it still contains plenty of organic matter and has great potential for reuse.

Instead of treating SMS as waste, think of it as an eco-friendly resource. Whether you’re an avid gardener, a farmer or just someone who enjoys sustainable practices, SMS has countless benefits to offer.


Practical Ways to Reuse Spent Mushroom Substrate

    1.    Soil Amendment and Composting

SMS works wonders as a soil conditioner. Its organic content improves soil structure, adds fertility and helps retain moisture. The leftovers from your harvest are perfect for gardening or farming.

It’s also a great compost booster. By adding SMS to your compost pile, you’ll accelerate decomposition and enrich your compost with essential nutrients. Whether you use it in your garden or farm, incorporating SMS can reduce the need for chemical fertilisers while supporting plant health.

2.    Animal Feed

When properly prepared, SMS can be used as a nutrient-rich, cost-effective supplement for livestock feed. It’s a sustainable way to add protein and other nutrients to animal diets without turning to more expensive or resource-heavy options.

3.    Bioenergy Production

For those interested in renewable energy, SMS can be converted into biochar or activated carbon through a process called pyrolysis. These materials are useful for energy production and can even double as soil additives. This makes SMS a great resource for those passionate about sustainability.

4.    Gardening Applications

In your garden, SMS can play several roles:

Mulching: Spread SMS around your plants to suppress weeds, retain soil moisture and regulate temperature.

Raised Bed Filler: Use SMS as a nutrient-rich base layer in raised garden beds to provide a strong foundation for your plants.

Reusing SMS in the garden not only benefits your plants but also cuts down on waste—offering a practical, eco-friendly solution for home use.


Why Should You Reuse Spent Mushroom Substrate?

Repurposing SMS isn’t just about practicality—it’s about sustainability. By reusing this by-product, you’re reducing waste, recycling valuable organic materials and contributing to more environmentally friendly practices. Whether you’re feeding livestock, enriching soil or supporting renewable energy efforts, SMS is a simple way to make a positive impact.


Grow, Reuse and Thrive with Merryhill Mushrooms

At Merryhill Mushrooms, we’re committed to sustainable mushroom cultivation. With our organic grow kits, you can enjoy fresh, homegrown mushrooms and easily repurpose the spent substrate for eco-friendly uses.

Start your journey today with one of our grow kits, and discover how growing your own mushrooms can reduce waste while rewarding you with fresh produce.

Authored by: Kieran