Plug spawn or loose spawn: which one do you need?
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Two products in our shop appear to do the same thing at first glance: plug spawn and loose spawn. Both are full of living mycelium, both exist to grow your own mushrooms. Yet you buy them for completely different projects, and picking the wrong one means months of waiting for nothing.
The short answer: if you are inoculating a log, stump or thick piece of wood, you want plugs. If you are growing indoors or on a balcony, on straw, coffee grounds or in a bucket, you want loose spawn. Here is why, and where the edge cases sit.
What exactly is plug spawn?
A plug is a hardwood dowel, 8 millimetres thick and 35 millimetres long, fully colonised by the mycelium of one species. You drill holes in a fresh log, tap the plugs in and seal them with the wax that comes with your order. From there the mycelium does the work, growing into the wood from dozens of points at once.
The strength of a plug is the wood itself. The mycelium already lives on wood fibre, so moving into your log is a small step. That makes plugs tough: they survive shipping, a few weeks in the fridge and a clumsy afternoon of DIY without complaint.
So what is loose spawn?
Loose spawn is mycelium on a carrier material, sold here in 80 gram pouches. It is meant to be mixed through a nutritious substrate: pasteurised straw, fresh coffee grounds, sawdust or a blend, usually in a bucket, tray or grow bag. Because you spread the spawn through the whole substrate, colonisation is much faster than in a log. With oyster mushrooms, think weeks instead of months.
The flip side: loose substrate is more fragile. You need to work clean, moisture matters more, and a bucket of straw contaminates far more easily than a solid beech log. Faster results also mean more moments where things can go wrong.
The difference at a glance
| Plug spawn | Loose spawn | |
|---|---|---|
| For | Logs, stumps, thick wood outdoors | Buckets, straw, coffee grounds, sawdust, indoors and out |
| First harvest | After 6 to 18 months | Often within 1 to 3 months |
| Harvest lifespan | Years from the same log | A few flushes, then the substrate is spent |
| Difficulty | Forgiving, little maintenance | Demands hygiene and attention to moisture |
| You need | Fresh log, drill, wax | Substrate, bucket or bag, clean hands |
Why does loose spawn not work well in a log?
It can be done, with special tools: inoculation tubes exist that press sawdust spawn into drilled holes, and professional shiitake growers work that way. Without that tool, though, you cannot get the spawn deep and protected enough into the wood. It dries out in the drill hole or gets cleaned up by birds and slugs before it can establish. For a single log in the garden, a plug is simply the better tool: it is made of wood itself, fits exactly and sits safely behind a layer of wax.
And plugs in a bucket of straw?
The same logic in reverse. A plug releases its mycelium slowly into loose material, because it is built to grow into solid wood. By the time a handful of plugs has worked through a bucket of straw, loose spawn would have finished three times over. It does work eventually, it is just a waste of your time and your plugs.
What if you want both?
Plenty of our customers do exactly that: inoculate a few logs with plugs in February or March for the long term, and run a bucket or grow bag with loose spawn in between for the quick harvest. The log is your savings account, the bucket your pocket money. If you first want to find out whether growing suits you at all, start with a grow kit: the substrate in there is already colonised, all that is left is harvesting.
Not sure for your situation? Email us what you have in mind (garden or balcony, indoors or out, patience or hurry) and we will tell you honestly which form fits. Sometimes that is the cheapest product, and we are fine with that.