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Spawn & Substrates
Horse Manure
Aged, screened horse manure for growing dung-loving and compost-loving mushrooms. You hydrate it, pasteurise it, then spawn it. A base ingredient, not a ready-to-fruit kit.
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Dry and stable in the bag. Hydrate and pasteurise before use.
Composted and sieved horse manure, dried for clean storage and easy weighing.
Button, cremini, portobello and other dung-loving species that need a manure base.
Hydrate to field capacity and pasteurise before spawning. No shortcuts.
The short version
This is aged horse manure, composted and screened, then dried so it stores cleanly and is easy to weigh out. It is the manure base that compost-loving and dung-loving mushrooms need.
It is not a finished substrate. You add water to bring it to field capacity, pasteurise it, let it cool, then add your spawn. Button, cremini and portobello (all Agaricus bisporus) and other coprophilous species fruit on a manure base and will not fruit properly on plain wood or grain.
What it is
A manure base, dried for storage
Horse manure is one of the classic bulk ingredients for mushroom growing. It has been composted and screened to remove large bits, then dried so it is light, stable and easy to weigh. Drying also lowers the free ammonia that fresh manure carries, which harms mushroom mycelium.
Many mushrooms in the Agaricus group, and other dung-loving (coprophilous) species, evolved to grow on grazing-animal dung and the rich soil around it. A manure base gives them the nutrition they expect. Plain straw, wood or grain will not give the same result for these species.
It is dry in the bag for a reason. You control the water and the heat treatment yourself, so the substrate is fresh and correctly handled when your spawn goes in.
How to use it
From dry bag to spawned substrate
A common home recipe is two parts manure to one part hydrated coco coir, often with a little vermiculite for moisture, plus a small amount of gypsum (around 2 to 5 percent of the dry weight) to help structure and pH. You can also use manure on its own. Adjust to your species and your own method.
Mix and hydrate
Break up the dried manure and combine with your other ingredients. Note that coir is itself dry and needs hydrating first. Add water and mix until the whole lot reaches field capacity: squeeze a handful and only a few drops should come out. Too wet invites contamination, too dry and the mycelium stalls.
Pasteurise
Hold the hydrated substrate at about 65 to 75 C for one to two hours. This knocks back competing moulds and bacteria while leaving useful heat-tolerant microbes. Do not boil it and do not skip this step.
Cool, then spawn
Let the substrate cool to room temperature. Working as cleanly as you can, mix in your grain spawn or culture. Pack into your container, then colonise at the temperature your species prefers.
Case and fruit
Button, cremini and portobello need a casing layer over the colonised compost to trigger fruiting, commonly a few centimetres of buffered peat. Other dung-loving species fruit straight off the surface. Follow the method for the mushroom you are growing.
Field capacity and a real pasteurisation step do most of the work. Most failures on manure substrate come from substrate that was too wet, or that was never heat-treated.
Storage and safety
Keep it dry, handle it sensibly
Stored dry and sealed, this keeps well. Once hydrated, treat it as perishable and use it promptly. Do not store wet manure for any length of time, as ammonia and off microbes build up fast.
It is composted animal manure, so handle it like any farm or garden material. Work in a ventilated space, wear gloves, and wear a dust mask for the dry powder or anything dusty. Wash your hands afterwards. Pasteurising is also your main safety control: research on manure-based mushroom substrate shows that holding it at composting and pasteurisation temperatures inactivates common pathogens such as E. coli, Salmonella and Listeria.
| Material | Aged, composted, screened horse manure, dried |
|---|---|
| Use | Bulk manure base for compost-loving and dung-loving mushrooms |
| Prep before use | Hydrate to field capacity, then pasteurise 65 to 75 C for 1 to 2 hours |
| Common mix | About 2 parts manure to 1 part coir, plus optional gypsum and vermiculite |
| Storage | Dry and sealed before use; use promptly once hydrated |
What it is not
Not a ready-to-fruit product
This bag will not grow mushrooms on its own. It has no spawn or culture in it, and it has not been hydrated or pasteurised for you. It is the manure ingredient, and you supply the rest of the method.
It is also not the right base for wood-loving mushrooms such as oyster or lion's mane, which prefer straw, sawdust or supplemented hardwood. Match the substrate to the species.
Common questions
Frequently asked
No. You hydrate it to field capacity and pasteurise it before adding any spawn or culture.
Compost-loving and dung-loving species such as button, cremini, portobello and other coprophilous mushrooms. Not for oyster or other wood-lovers.
Yes. Holding it at about 65 to 75 C for one to two hours knocks back competing moulds and bacteria and is your main safety step. Skipping it usually means contamination.
For button, cremini and portobello, yes. A casing layer over the colonised compost, commonly a few centimetres of buffered peat, triggers fruiting. Many other dung-lovers fruit straight off the surface.
A small amount, around 2 to 5 percent of the dry weight, helps structure and pH. It is optional but common.
Treat it like any composted manure. Work in a ventilated space, wear gloves and a dust mask for the dry powder, and wash your hands. Pasteurising the hydrated substrate inactivates common pathogens.
It is generally spent for growing once it has fruited out, but it composts well and is good for the garden.
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Sold as a horticultural growing material. Cultures and spores are supplied for microscopy and legal gourmet cultivation only.
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