The Benefits of Growing Mushrooms Using Spent Blocks: Circular Systems

Mushrooms are more than just a tasty ingredient; they offer a sustainable way to grow food and improve the environment. Growing mushrooms at home is easy, rewarding, and helps reduce waste. One of the easiest and most affordable ways to do this is by using spent blocks from commercial mushroom growers. These blocks, often discarded after harvest, still hold great potential for producing food and enriching your garden. This post explains why growing mushrooms with spent blocks is a smart choice and how you can get started.

Harvest from spent mushroom blocks: 2nd fruit.

Why Growing Mushrooms Matters

Growing mushrooms at home offers several benefits:

• Fresh, nutritious food: Mushrooms are rich in vitamins, minerals, and antioxidants. Many have antioxidant and anti-inflammatory properties, contributing to overall health and wellbeing.

• Low space and resource needs: They require little space and water compared to other crops.

• Environmental benefits: Their mycelium breaks down organic matter, helping recycle nutrients, making them bioavailable in the soil.

• Economic savings: Growing your own mushrooms cuts grocery bills and gives you gourmet ingredients for little to no cost.

  
  

Mushrooms also support biodiversity by encouraging healthy soil ecosystems. They form networks called mycelium that connect plants and improve soil structure. These mycelial structures can even help transmit information and nutrients across their networks to help support the growth of plants in need of specific resources.

What Are Spent Blocks and Why Use Them?

Spent blocks are the leftover substrate after commercial mushroom growers harvest their crops. These blocks usually consist of straw, sawdust, or other organic materials inoculated with mushroom spores. After the main harvest, the blocks still contain living mycelium and nutrients, but commercial growers usually can't wait until the 2nd, 3rd, 4th and even sometimes 5th flush in order to keep up with their demand from restaurants and other clients.

Using spent blocks has several advantages:

• Reduces waste: Instead of throwing blocks away, you give them a second life.

• Provides free food: Spent blocks can produce additional mushroom flushes (pounds of food) at little to no cost.

• Improves soil: When broken down, spent blocks make excellent compost, adding a rich carbon source from all of the sawdust, and a bit of nitrogen from the mycelium.

• Adds mycelium to garden beds: This supports plant health and soil life. Did you know that mycelium in your soil is a sign that your soil is healthy and thriving?!

  
  

By reusing spent blocks, you help close the loop in food production and reduce environmental impact.

How to Grow Mushrooms Using Spent Blocks

Growing mushrooms from spent blocks is simple and requires minimal equipment. Here’s how to get started:

1. Find spent blocks

   Contact local mushroom farms or markets to ask if they have spent blocks available. Many growers are happy to give them away or sell them cheaply.

   
   

2. Choose a suitable location

   Mushrooms like shady, humid spots. A covered patio, basement, or shaded garden corner works well. In New Orleans, in the shade under a cluster of banana trees is prime real estate for mushrooms.

   
   

3. Prepare the blocks

   Keep the blocks moist by misting them daily. Avoid soaking them, as too much water can cause mold. Stay tuned for another post on the different ways you can experiment with growing techniques with spent blocks.

   
   

4. Encourage fruiting

   Lower the temperature slightly and increase fresh air circulation. Small cuts or holes in the block can help mushrooms emerge.

   
   

5. Harvest mushrooms

   Pick mushrooms when caps open but before they start to drop spores. This usually happens within a week or two.

   
   

6. Reuse or compost the block

   After several flushes, the block will stop producing. Use it as compost or mix it into garden soil to add nutrients and mycelium.

   
   

Growing mushrooms can be a great way to add more nutritious ingredients to your meals, and is a great way to learn about life cycles right from your own home while you reduce waste and add a little diversity to soil life in your garden.

Tips for Success

• Keep blocks moist but not wet

Mist regularly and avoid drying out.

• Maintain good air flow

Mushrooms need fresh air to fruit well.

• Protect from pests

Use netting or barriers if slugs or insects are a problem.

• Be patient

Mushrooms may take a few days to appear after adjusting conditions.

• Experiment with different mushroom types

Oyster mushrooms are especially easy to grow on spent blocks but there are so many kinds of mushrooms out there to develop a relationship with!