Whether you're growing at home or scaling up your mushroom farm, understanding and choosing the right type of mushroom spawn is key to keeping your operation efficient and productive. In this post, we compare grain spawn and sawdust spawn breaking down their environmental impact, costs, contamination risks, ease of manufacture and explore smart strategies to help you save time and money.
Grain Spawn vs Sawdust Spawn: What's the difference?
Grain spawn
- Made by inoculating sterilised cereal grains like rye, wheat or millet.
- It has a higher nutrient profile when compared to saw dust.
- In general, this is the spawn choice in America.
Sawdust spawn
- Produced by inoculating sterilised or pasteurised hardwood sawdust.
- This is the spawn choice in Japan.
Both serve as carriers for mushroom mycelium, but their characteristics differ and these differences matter depending on your goals.
Pros and Cons at a glance
Grain spawn
- Pros (positives): Fast colonisation. High nutrient profile.
- Cons (negatives): Higher cost. Contamination risks.
Sawdust spawn:
- Pros (positives): Cheaper & eco-friendly. Lower contamination risk.
- Cons (negatives): Slightly slower colonisation. Still needs grain spawn to inoculate.
Ease of Manufacture
Grain Spawn:
- Requires pressure sterilisation and high hygiene standards.
- Higher contamination risk during manufacture and storage.
- Easy to scale once you have the infrastructure & equipment.
Sawdust Spawn:
- Can be made with steam pasteurisation (simpler than sterilisation).
- If you steam pasteurise fruiting substrate then you can make sawdust spawn.
- Also, great for DIY growers using low-cost equipment.
Winner: Sawdust spawn for a low-tech manufacturing method that many growers may already be using.
Environmental Impact
Grain Spawn:
- Pros: Utilises UK grown agricultural products.
- Cons: Requires high-energy sterilisation.
Sawdust Spawn:
- Pros: Often made from waste wood, biodegradable, best for outdoor log/stump inoculations (doesn’t attract pests).
- Cons: Can be harder to source sustainably depending on region.
Environmental winner: Sawdust spawn for a lower-carbon footprint, especially in outdoor or low-tech setups. That said we use saw dust spawn for the majority of our fruiting blocks.
Cost Comparison
Grain Spawn:
- More expensive per kilo due to grain costs and energy-intensive sterilisation.
- Needs to be refrigerated once colonised to reduce fruiting in the bag.
Sawdust Spawn:
- Cheaper to produce in bulk, especially if already making fruiting blocks.
- Longer shelf life if stored well (less nutrients reduce tendency to fruit in the bag).
Cost-effective pick: Sawdust spawn, especially for outdoor or larger-scale growers.
Contamination Risk
Grain Spawn
- High contamination risk if sterilisation isn't perfect.
- Grains are a nutrient-rich target for mould and bacteria.
Sawdust Spawn:
- Slightly more forgiving and less nutrient-dense, so lower risk.
- Often pasteurised, not sterilised.
Safer option: Sawdust spawn for beginners or lower-tech setups.
Cost-Effective Strategies for Growers
1. Make your own spawn
- If you have time and basic equipment both grain and sawdust can be made with pressure cookers and clean workspaces.
2. Use sawdust spawn for logs, beds, and outdoor projects.
- It’s cheaper, easier to handle, holds up well and it doesn’t attract pests.
2. Use grain spawn for rapid colonisation in bags or jars.
- Especially good for fast-growing species like Oyster Mushrooms or Lion’s Mane.
- It’s great to supplement low nutrient substrates e.g. coir mixes.
4. Experiment with “master spawn”
- Make (or buy) grain spawn and use it to inoculate saw dust spawn for extended savings.
- For example, you can use 1kg of grain spawn to inoculate 30kg of saw dust spawn which in turn can inoculate 360kg of supplemented fruiting substrate.
Conclusion
- There’s no one-size-fits-all solution.
- Your ideal spawn depends on your setup, scale and goals.
- But with the right strategy, you can make big savings and keep your growing sustainable.
