How Many Days Between Mushroom Flushes to Expect
I have lost count of how many growers have messaged me three days after a beautiful first harvest, sure that something has gone wrong because the block has gone quiet. Nothing is wrong. For most gourmet and functional mushrooms grown on a small block or bag, you should expect roughly 7 to 14 days between the end of one flush and the harvest of the next, and later flushes usually run toward the longer end of that window.
Button mushrooms are the tightest and most predictable, spaced about 7 to 8 days apart. Oysters, shiitake, and lion's mane are looser. The single biggest thing that decides whether your next flush lands in one week or three is not luck, it is whether you put the water back into the block after you harvest.
Out-Grow Quick Answer
- Expect about 7 to 14 days between flushes for most gourmet mushrooms, and about 7 to 8 days for button mushrooms.
- Each individual flush takes about 3 to 7 days from the first pins to a full harvest.
- The first flush is the biggest. A second flush near 60 percent of the first is normal, and a third is smaller again.
- Rehydrating the block, by soaking or heavy watering, is the biggest lever you have on how fast the next flush arrives.
- Most growers get 2 to 3 usable flushes per block. A substrate can physically push 3 to 5, but the later ones rarely pay for the space.
Those are ranges on purpose. Anyone who hands you a single number, like exactly ten days every time, is selling tidiness that the mushrooms do not actually follow. Here is how the range breaks down and how to steer it.
The gap is really two clocks stacked on top of each other. First the mycelium needs a few days to recover and reorganize after the drain of fruiting. Then, once new pins set, they need another 3 to 7 days to size up. Add those together and you land in that one to two week window. When the gap runs long, it is almost always the recovery clock that stalled, usually because the block dried out and never got rehydrated.
How Long Does a Mushroom Flush Last
The first time I really paid attention to the clock on a single flush, I was tracking a wall of blue oyster bags by hand and writing pin dates on the bags with a marker. The pattern was hard to miss. Once pins set, most cultivated mushrooms go from tiny primordia to full harvest in about 3 to 7 days. Oysters can move faster near the warm end, sometimes seeming to double overnight, while denser species take the longer end.
Before going any further, it is worth pinning down exactly what I mean by the word.
One complete wave of mushroom production, from the first visible pins through a full harvest. A single block or bag normally produces two or more flushes over its working life, separated by a rest and rehydration period, which is the gap this article is about.
That is the flush itself, the visible growing part, and it is short. The reason the whole cycle feels long is the quiet stretch on either side of it, the recovery before pins and the sizing after. If you only watch the bag during the growing days, the rest of the wait feels like failure. It is not, it is the mycelium working where you cannot see it.
Days Between Flushes by Species
People want one rule, and the honest answer is that the rule changes with the species. The numbers below are the ones I come back to when someone asks what is normal for their block. Treat them as planning ranges, not promises, because your strain, substrate, and room all nudge them.
| Species | Usable flushes | Typical gap between flushes | What to expect |
|---|---|---|---|
| Button, Agaricus | 2 to 3 | 7 to 8 days | The most regular clock of the common species, on cased compost. |
| Oyster, Pleurotus | 2 to 3 | 7 to 14 days | Fast and forgiving, with a strong first and second flush. |
| Shiitake, on a block | 2 to 3, sometimes more | 1 to 3 weeks | Often rested and soaked on purpose between flushes. |
| Lion's mane | 1 to 2 | 1 to 2 weeks | Gives one or two strong flushes, then drops off quickly. |
Notice that the flush count and the gap move together. The species that rest longer between flushes, like shiitake, are also the ones you can coax more flushes out of, because that rest is doing real recovery work. The fast species spend their charge sooner.
How to Trigger a Second Flush of Mushrooms
When a block stalls after the first flush, the fix I give on the support desk is almost always the same three words: soak the block. A first flush pulls a surprising amount of water out of the substrate, and a dry block simply cannot build the next round of pins no matter how long you wait. Here is the routine that works, and it is deliberately boring.
How to Set Up the Next Flush, Step by Step
Harvest clean
Pick everything and remove stumps and aborts. Leftover tissue rots and invites mold on an already tired block.
Rehydrate
Soak the block in cool clean water, weighted down, for several hours up to overnight, or water it heavily if soaking is not practical.
Drain
Let the excess run off so the block is fully moist but not sitting in standing water, which sours a block fast.
Return to fruiting conditions
Put it back in normal humidity, light, and fresh air exchange for its species. Do not change the recipe between flushes.
Wait for pins
Give it several days to about a week. New pins usually appear inside two weeks of the last harvest.
That is the whole trick. No cold shock, no special trigger, no new ingredient. On most species a thorough soak and a return to the same conditions that gave you the first flush is all it takes to bring the second.
Should You Dunk Mushroom Blocks Between Flushes
Yes, for blocks and bags, dunking or heavy watering between flushes is the highest value habit you can build. The failure I see most often in stalled second flushes is not contamination or bad genetics, it is a block that was never rehydrated and slowly went too dry to pin. Replacing that lost water is what keeps a block on the one to two week schedule instead of dragging out for a month or never flushing again.
Here is the plain trade-off on rehydrating, since the habit is not entirely free of things to watch.
- Replaces the water the first flush pulled out of the block
- Keeps the next flush on the normal one to two week schedule
- The single highest value habit for total yield over a block's working life
- Must drain fully, or standing water sours the substrate
- Needs weighting down in the soak so the block does not float
- Trays and beds are watered rather than lifted, so the technique differs by vessel
With that trade-off in mind, here is how the technique changes depending on what you are growing in.
Trays and beds work a little differently, since you water the casing or surface rather than lifting and soaking a whole block, but the principle is identical. Put back the water the last flush took, without leaving the substrate waterlogged.
Why Your Second Flush Is Smaller Than the First
Almost everyone notices it and worries about it: the second flush comes in lighter than the first, and the third lighter again. That is normal, and it is not something you did wrong. A colonized block holds a finite amount of easy food and water, and the first flush spends the richest, most available share of both.
There is real biology underneath the drop. In button mushrooms, the first flush leans on a sugar called mannitol to drive the mushrooms open, and by the second flush the block has shifted toward using nitrogen rich building blocks as the easy carbon runs low. The mushrooms keep coming, but the block is working harder for them, so they arrive slower and smaller. One quiet upside is that later flushes are not simply worse, some quality measures actually hold up or improve even as the weight drops.
How Many Flushes a Mushroom Substrate Is Good For
This is where I gently talk people down. Early on I chased every last flush myself, babysitting tired blocks for a fourth or fifth round while fresh bags waited for space. The math almost never worked. Most blocks give 2 to 3 flushes that are genuinely worth harvesting. A substrate can physically push 3 to 5 if you keep it hydrated, but yield and quality fall off a cliff, and the later flushes carry more contamination risk on aging, broken down substrate.
Plan for two flushes as your standard, and treat a third as a bonus rather than a promise.
The commercial version of this decision is even blunter. Large farms often run a one and done or a two flush plan and then reset the space, because tying up a fruiting room with a low yield third flush costs more than the mushrooms are worth. At home you have more slack, so if a particular block keeps giving you clean, decent flushes, ride it. Just do not feel obligated to squeeze a block dry out of guilt.
Common Bad Advice About Days Between Flushes
A lot of beginner content flattens all of this into rules that sound precise and set people up to worry. These are the ones I correct most often.
Every block reliably gives four or five flushes if you just keep misting.
A block can physically manage 3 to 5, but yield drops sharply after the second or third, and most growers stop there for good reason.
Flushes always come exactly every 7 days.
Button mushrooms run about 7 to 8 days, but most species range from 7 to 14 days or longer, especially on later flushes.
You do not need to soak between flushes to get the same result.
Skipping rehydration is the top cause of weak or failed second flushes on blocks and bags. Replace the water the last flush took.
Relevant Out-Grow Supplies
The between-flush routine only needs a vessel that holds moisture and takes a soak well. If you are buying, here is what actually helps, with an honest note on fit.
- All in one grow bags are the easiest way to run the soak and reflush cycle, since the whole colonized block lifts out for a dunk and goes back in. This is the vessel I reach for when I want repeat flushes with the least fuss.
- Mushroom grow bags are the do it yourself option if you prepare and sterilize your own substrate and want to control the recipe from scratch.
- Mushroom grow kits are the simplest starting point if you just want to see a first and second flush without prepping anything. Most beginners get their first two flushes from a kit before moving up.
The Bottom Line on Days Between Flushes
Between flushes, plan on roughly one to two weeks, a little tighter for button mushrooms and a little longer as a block ages. The number itself matters less than the habit that controls it: harvest clean, put the water back, and return the block to the same conditions that gave you the first flush. Do that and two solid flushes are the reliable baseline, with a third as a bonus. Stop chasing an exact day, and start reading what the block has left to give.
About the author
Mike Wiberg is the founder of Out-Grow, a mushroom cultivation supply company he has run since 2009. He developed the original all in one mushroom grow bag in 2014, a format now used across the hobby, and over more than 20 years of hands-on mycology he has grown hundreds of species and researched substrate formulations from the lab bench. He maintains one of the largest commercial culture libraries online, including a working collection of more than 300 species under a USDA permit. His cultivation work has been cited in peer reviewed research published in Frontiers in Cellular and Infection Microbiology, and he is one of only a handful of growers with a documented successful clone of Matsutake, one of the most difficult species in cultivation. He has helped growers troubleshoot cultivation problems for nearly two decades, and he writes from the lab and the grow room, not from a keyword list.
Days Between Flushes FAQ
About 7 to 14 days for most gourmet mushrooms, and about 7 to 8 days for button mushrooms. Later flushes usually run toward the longer end. The gap covers both the mycelium recovering and the new pins sizing up.
From the first visible pins to a full harvest is usually about 3 to 7 days. Oysters move faster in warm conditions, while denser species take the longer end of that range.
Most kits give 2 to 3 usable flushes. The first is the largest, and each one after is smaller. Rehydrating the block between flushes is what lets you reach the third.
Oysters typically give 2 to 3 flushes spaced about 7 to 14 days apart, with a strong first and second flush and a lighter third.
Yes. For blocks and bags, soaking or heavily watering between flushes replaces the water the last flush used, and it is the single biggest thing keeping the next flush on schedule.
It is normal. The first flush spends the richest, most available food and water in the block. A second flush near 60 percent of the first, and a smaller third, is the expected pattern, not a mistake.
Give a rehydrated block at least two to three weeks under good fruiting conditions before calling it done. If there is no pinning and no contamination by then, the block is likely spent.
Many run only two flushes, or even one, then reset the space. A low yield later flush ties up a fruiting room that a fresh block could use more profitably.