Is it ready to pick?
Answer this standing in front of the block. It reads what you can actually see against this page's own signal for your species and gives you pick now, within a day, or not yet — plus the check that settles it and what waiting costs you.
This reads what you report, not the mushroom itself. It weighs what you can see above the day count on purpose, because a block held cool runs days behind one held warm and the calendar will happily tell you the wrong thing. Where it is unsure it leans toward picking, because a mushroom picked a day early is still a good mushroom and one picked a day late may not be sellable at all.
The signals above are the same ones in the table further down this page. Recording the weight of each flush in the free Grow Log is what turns harvest timing into a number you can compare: it works out your biological efficiency per batch, so you can see whether picking earlier or later actually changed your yield. Free, no account needed.
The signal is the cap, not the calendar
Almost every harvest guide leads with a number of days. That number is close to useless on its own, and it is the reason so many growers pick late. The same oyster block fruits in four days at 21 °C and eight at 13 °C. The day count tells you roughly when to start looking. What tells you to pick is the mushroom.
For most gourmet species the single most reliable signal is the cap margin — the rim of the cap, seen from the side. While a mushroom is still growing, the margin curls under toward the gills. As it matures the margin flattens out, and once it turns up and goes wavy the mushroom has finished and is releasing spores. The right moment is the flat one, just before it turns up.
The exceptions are the species that do not really have a cap. Lion's mane is judged on the length and colour of its spines. Enoki is judged on stem length while the caps are still closed. Reishi and turkey tail are grown for extract rather than weight, so the signal there is the white growing margin closing up rather than anything to do with gills.
Spore drop is the point of no return
The moment a mushroom starts dropping spores, three things get worse at the same time and none of them recover.
- It stops gaining weight and starts losing it. Up to peak the fruit is pulling mass out of the block. After peak it is spending stored mass on spores and drying out. Waiting past peak to get a heavier harvest does the opposite.
- The texture goes. Oysters toughen and turn bitter, shiitake dry at the cap edge, lion's mane yellows and turns sour.
- Shelf life collapses. This is the one that costs money. A cluster picked at peak keeps for a week in a paper bag under refrigeration. The same cluster picked two days later can be unsellable to a wholesale or restaurant buyer within a day, because it arrives already soft.
There is a fourth cost that has nothing to do with the mushroom. Heavy spore drop loads the fruiting room, and spores settle on every other block in it. That is both a route for contamination and, at commercial density, a genuine respiratory irritant. Growers who fruit oysters in a small room and start reacting to it are usually harvesting late, not allergic.
Harvest signal by species
The row you want is "ready to pick". These are the same descriptions the checker above uses. Pins-to-harvest windows are given only where we publish one; for everything else the general figure on this site is 4 to 10 days from pin set.
| Species | Ready to pick when | Past peak when | Pins to harvest |
|---|---|---|---|
| Oyster (blue, pearl, pink, golden) | Edges just uncurling, caps almost flat | Caps flat or wavy with the edge turned up | 4 to 7 days |
| King Oyster | Stem firm at full length, cap just beginning to flatten | Cap flattened and turned up with the gills exposed | not published |
| Lion's Mane | Spines 1 to 2 cm and hanging clearly, still white | Spines long and shaggy, surface yellowing or browning | not published |
| Shiitake | Cap 60 to 80% open, edge still curled under | Cap flat or turned up with the gills fully exposed | 5 to 10 days |
| Chestnut / Pioppino / Nameko | Veil just breaking, cap edge still curled under | Veil broken and caps flat with the gills open | not published |
| Enoki | Stems at full length, caps still small and closed | Caps opened out and darkening | not published |
| Maitake | Fronds thin and fanned out, edges still pale and rounded | Frond edges hardened, dry or cracked | not published |
| Reishi / Turkey Tail | Colour full to the edge, the white growing margin nearly gone | Edge hard and fully coloured, growth stopped | not published |
Fruiting temperatures and colonisation times for all 14 species are in the free Fruiting Conditions cheat-sheet. For the stage before this one, see how to get mushrooms to pin.
How to actually take it off the block
- Take the whole cluster. Grip it at the base where it meets the block and twist gently rather than pulling straight out. Cutting with a knife leaves a stub that rots and gives contaminants a foothold before the next flush.
- Do not wash it. Mushrooms absorb water and a washed mushroom goes slimy. Brush off substrate and trim the base instead.
- Weigh it and write the number down before it goes in the cooler, and weigh each flush separately. A flush weight is the only way to find out whether a change you made did anything.
- Cool it quickly, in paper. Plastic traps moisture and halves shelf life. Paper bags or vented crates at 2 to 4 °C.
- Rest the block and re-initiate. Most species give another flush in 1 to 2 weeks. A block that will not restart is covered in the pinning guide.
Every flush, weighed and compared
Log each harvest in Mycro and it works out biological efficiency per batch, per flush and per strain, so "should I have picked that a day earlier" stops being an opinion. Free, no account, no cap on how many batches you track.
Try the free Grow Log → Become a Founding Grower — $99 →$99 once · opens a sign-in account today · lifetime founder pricing · a direct say in what we build first · fully refundable any time.
Frequently asked questions
When should you harvest oyster mushrooms?
Harvest an oyster cluster when the edges of the largest caps have just started to uncurl and the caps are almost flat, but before the margin turns up and goes wavy. That is usually 4 to 7 days after pins appear, though temperature moves that a lot. Take the whole cluster at once rather than picking the big ones and leaving the small: an oyster cluster is sold as a cluster, and the ripest mushroom in it sets the clock for all of them.
How do you know when lion's mane is ready to harvest?
Judge lion's mane on its spines rather than its size. It is ready when the spines have lengthened to roughly 1 to 2 cm and hang clearly from the surface while the whole fruit is still white. Once the spines go long and shaggy and the surface starts to yellow or brown, it is past peak and will taste bitter. Lion's mane discolours before it drops any visible spores, so colour is the signal to watch, not spore dust.
What happens if you harvest mushrooms too late?
A mushroom left past peak starts releasing spores, and from that moment three things get worse at once. It loses weight rather than gaining it, because it is now spending stored mass on spores and drying out. The texture toughens and, in oysters, turns bitter. And shelf life collapses, so a cluster that would have kept a week is unsellable in a day or two. Heavy spore drop also loads the fruiting room, which is both a contamination route and a genuine respiratory irritant at commercial density.
General guidance from common cultivation practice, not guarantees — ripeness is a judgement call and your results vary with strain, substrate and conditions. Mycro is for legal culinary & medicinal mushrooms only.