Mushroom Fruiting Blocks: Growing Guide for Beginners

Mushroom Fruiting Blocks: Growing Guide for Beginners

You've just acquired your first ever fruiting block and now the adventure truly begins! Let us show you how to nurture your block and maximize your harvests.

Maintaining your own mushroom block at home is a fascinating and rewarding endeavor that combines the joys of gardening with the culinary delights of fresh mushrooms. Here's a detailed guide to help you through the process, combining insights from several top sources on the web.


Choosing the Right Mushrooms to Grow

Start by selecting the right mushroom species for your gardening experience. Oyster & Lion's Mane mushrooms are recommended for beginners due to their quick growth and versatility in substrates. Shiitake mushrooms offer a richer flavor and are popular in culinary uses, while button mushrooms are common and easy to grow. Wild varieties like morel mushrooms should be avoided for indoor cultivation. Consider your indoor growing conditions and your level of experience when choosing your mushroom type.

Preparing Your Substrate

The substrate is essentially what your mushrooms will grow on, in nature this can be almost any organic material. You can find hundreds of recipes for grow blocks and they all work. But for us, we do the following recipe for a 5 lb block.

- 5 cups of hardwood pellets

- 1400 ml water

- 1.25 cups wheat bran

Common substrates include hardwood sawdust, straw, coffee grounds, coco coir, and a mixture of these. Enhanced substrates typically contain additives to increase nutrition for the mycelium to grow on, such as wheat bran and gypsum.

It's crucial to sterilize and seal your fruiting block to prevent unwanted contamination. This can be done through soaking in hot water, using an Instapot or using a pressure cooker​​​​. It is preferable to maintain 15psi for 120 continuous minutes to completely sterilize your blocks. Sawdust is very dense and a good insulator so this is the most crucial part of mushroom cultivation!

I have achieved a near 95% success rate on my blocks during incubation using both a Presto Pressure Cooker and an Impulse sealer.

Inoculation and the "Spawn Run"

Inoculation involves introducing mushroom spawn to your sterile substrate. It's vital to work in a clean, sterile environment to prevent contamination. We use rye grain spawn already inoculated with mushrooms to act as a starter. I will gently seal my bags during sterilization with a rubber band or neat folds so they are only exposed to open air when the grain spawn is mixed in.

Once inoculated, the substrate must be kept at specific temperature and humidity levels to encourage the Spawn Run! This incubation period varies depending on the mushroom variety and temperature. I use the coolest closet in the house as a spawning hotel for all of my blocks and it works very well. 

To achieve full colonization, the mycelium may take up to a month depending on a myriad of variables. I will gently massage the bags as they spawn out to damage the mycelium. The damage to the mycelium will release growth hormones that will tell your mycelium to continue growing.

Fruiting Conditions

After the mycelium has fully colonized the substrate, it's time to create the right conditions for fruiting. This involves adjusting temperature and humidity to optimal levels for mushroom growth, typically between 60°F and 70°F, with 85-95% humidity. Light exposure is also crucial; mushrooms need indirect or diffused light to stimulate development.

Here is a list of steps for inducing the mushroom flushes on your blocks:

1. Clean the outside of the block with alcohol

2. Make 2-3 small incisions with a sterile blade, its okay if you cut the mycelium a little bit!

3. Spray some water on those spots, just this once.

4. Wait and watch!

I would recommend purchasing a small clear plastic tote and drilling sets of 1" holes in the sides to act as a fruiting chamber. These are a cheap option for beginner growers that allow consistent humidity control with daily misting. Just be sure not to directly spray the cuts you made on the block.

Harvesting Techniques and Block Maintenance

Harvesting should be done when mushrooms reach their desired size, usually just before the veil breaks. Oyster mushrooms are ready when the cap starts to flatten out, and Lions Mane is ready when the spines start to elongate. Use a twist-and-pull method and give the block a good misting. After harvesting, it's essential to maintain your mushroom block for continued fruiting. This involves monitoring and adjusting humidity (around 90% to 95%), maintaining appropriate temperatures (55°F to 65°F for most varieties), ensuring proper air exchange, and removing any contaminated blocks​​.

After your block has had a few mushroom flushes and shrunk in its bag, its time to recycle. These blocks are great to use in the garden or compost, and will help boost your plants.

Troubleshooting Common Issues

The largest issue mushroom growers face is contamination because it is a permanent factor even in the cleanest of clean-rooms. Using sterile practices and quality genetics can help reduce this. Contamination is easily spotted with a flashlight and observation of multiple fruiting blocks.

I normally see contamination being an issue if your sterilization protocol was broken, like you did two split hours. If you notice suspicious looking growth, immediately take care of it. Competitor molds will always outgrow a desired mushroom mycelium. You typically have a day or 2 to mitigate your mold before you risk sporulation and contamination of your whole operation.

It is very common for beginners to question if the mycelium is mold. The biggest tip I can lend is to let the bag grow a few more days and observe, nothing can be lost if the bag stays sealed. Also your mushrooms will likely suffer aborted yields, or no yields at all if they are battling contamination. So it is important to clean your fruiting chamber environment on a weekly basis with peroxide or alcohol.

Maintaining your own mushroom block at home can be a straightforward and enjoyable process with the right preparation and care. By understanding and implementing these detailed steps, you're well on your way to cultivating your own delicious mushrooms right at home.

For more detailed instructions and tips, the sources mentioned offer comprehensive guides and insights into the nuances of mushroom cultivation.


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