How to grow a mushroom kit at home
A grow kit is a block of substrate that mushroom mycelium has already fully colonised. You don't need any special equipment: the block just needs fresh air, humidity and indirect light to switch from growing mycelium to producing mushrooms. Most oyster kits give their first harvest within two weeks of opening.
Where to put it
| Need | What works | Avoid |
|---|---|---|
| Light | Indirect daylight, or a room you'd be happy to read in | Direct sun, which dries the surface |
| Air | A kitchen counter or shelf with normal air movement | A closed cupboard, where CO₂ builds up and stems grow long and thin |
| Humidity | Misting twice a day, or a loose tent of a clear bag with holes | Heater or air-conditioner vents |
| Temperature | Most oysters and lion's mane: 60–75 °F. Pink oyster: warmer | Pink oyster below about 60 °F |
Starting the kit
- Cut a small X or slit in the plastic where the kit tells you to, or open the marked side. Mushrooms form where the block meets the air.
- Mist the opening and the air around it with clean water once or twice a day. You want it to look damp, not dripping.
- Within a week or so you should see small bumps, called pins. From then on they grow quickly, often doubling in size in a day.
When to harvest
Oysters: pick the whole cluster when the caps are still slightly curled under at the edges, just before they flatten out. Twist it off at the base or cut it flush with the block. If you wait too long, the caps drop a fine white spore dust and the texture toughens.
Lion's mane: harvest while the spines are short and the head is firm and white. Yellowing or long dangling spines mean it's past its best.
Fresh mushrooms keep best in a paper bag in the fridge. Use them within a few days.
Second flushes
After the first harvest, let the block rest for a week or two and keep misting lightly. Many blocks produce a second, smaller flush, and some a third. If the block feels light and dry, soak it in cold water for a few hours, drain it, and go back to misting.
Common problems
- Long, thin stems and small caps: not enough fresh air. Move the kit out of any enclosed space.
- Cracked, dry caps: the air is too dry. Mist more often, or tent the kit loosely.
- Nothing after two weeks: check the temperature, open a second slit, and mist the cut area directly.
- Green or black patches: that's mould, not mushroom. Keep the kit away from your food and compost it.
Local kits
We grow oyster and lion's mane kits in small batches in Groton, Massachusetts. See the mushroom grow kits we offer, and reserve from our next batch.
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