Grow problems
Why are my mushrooms not pinning?
Updated
Mushrooms usually fail to pin for one of two reasons: the block is not fully colonized yet, or nothing has told it to fruit. Pins form when the block is fully white and then gets a change: cooler air, more fresh air, higher humidity, and light. Check those four, give it a week, and most blocks start to pin.
Is the block fully colonized?
A block is ready when it is white all the way through, firm, and you cannot see much of the substrate. Patches of brown sawdust or straw mean the mycelium is still working. Starting fruiting early is the most common reason a block sits for weeks with no pins. Give it another week in warm, dark conditions.
Yellow or amber drops on the surface are normal. They are liquid the mycelium makes, and they often show up when it is close to done.
Did the block get a fruiting trigger?
In the wild, mushrooms fruit when the weather turns: cooler nights, rain, and open air. At home you copy that. Most profiles drop the temperature a few degrees and raise humidity when pinning starts.
| Mushroom | Colonization | Pinning | Pinning humidity |
|---|---|---|---|
| Pearl Oyster | 24 °C (75 °F) | 18 °C (64 °F) | 93% |
| Blue Oyster | 22 °C (72 °F) | 15 °C (59 °F) | 94% |
| Lion's Mane | 22 °C (72 °F) | 18 °C (64 °F) | 94% |
| Pink Oyster | 27 °C (81 °F) | 24 °C (75 °F) | 92% |
| Chestnut Mushroom | 23 °C (73 °F) | 16 °C (61 °F) | 95% |
| Beech / Buna Shimeji | 22 °C (72 °F) | 16 °C (61 °F) | 94% |
Pink Oyster stays warm the whole way, with only a small drop. Cool-weather species such as Blue Oyster pin best with a bigger drop.
Is there enough fresh air?
Pins need far more fresh air than colonization. A sealed bag or a closed tub can colonize well and then never pin because carbon dioxide stays high. Open the bag where the kit says, cut an X, or add holes, and fan a tent several times a day. In its pinning stage Blue Oyster runs a fan run of 40 s every 12 min. See humidity and fresh air for mushrooms.
Is there enough light?
Most species need light to know where to fruit. About 12 hours a day of indirect daylight or room light is enough. A dark closet can stall pins. Enoki and button mushrooms are exceptions and fruit in the dark.
Is humidity high enough at the surface?
If the cut opening dries out, pins cannot form there. Keep the surface damp but not wet. The profiles here pin at 86 to 95% humidity.
Does your species need something special?
- Shiitake needs weeks of browning, then a cold shock. In its profile that is 21 days of browning and a 1 day cold shock at 16 °C (61 °F) before it fruits.
- Maitake and Reishi are slow. Reishi often grows antlers before it forms a cap.
- Button / Cremini needs a casing layer on top of compost before it pins.
What if it still will not pin?
If a fully white block has had a week of fruiting conditions with no pins, try a stronger trigger: a few days a bit cooler, or soak the block in cold water for a few hours, drain it, and put it back. Many growers find that wakes it up. If the block shrinks away from the bag, smells sour, or shows colored patches, it may be old or contaminated. Read mushroom contamination.
FAQ
How long does it take for mushrooms to pin?
Usually a few days to two weeks after fruiting conditions start. In the profiles here pinning runs from 3 days for the fastest species to about 21 days for the slowest.
Do mushrooms need a cold shock to pin?
Most do best with a drop of a few degrees, and shiitake needs a real cold shock. Warm species such as pink oyster pin without one.
Should I open the bag before it is fully colonized?
No. Opening early lets mold in and invites the block to fruit before it has the energy. Wait until it is white all the way through.
Why are my pins forming inside the bag?
Pins inside the bag mean the block is ready and is getting fresh air or light through the plastic. Open the bag at that spot so they can grow out.