Mushroom farm: the third flush costs you two rooms

“People told me: you have already paid for the compost, so take everything it has. And I did. Until I worked out that the third flush was costing me two rooms out of six.”

Olha Verbytska runs a mushroom farm in Drohobych. Eleven years in mushrooms, eight of them as the owner. Six growing rooms of button mushrooms, with compost bought in ready and spawned. Nineteen people, twelve of them on picking.

The year closed with 2 976 000 ₴ of profit on revenue of 24 240 000 ₴. Twelve percent. Normal for the trade, which is exactly why nobody went looking for where almost half as much again was lying.

It was not in the yield and not in the price. It was sitting in the calendar.

Olha counted her farm the way every grower counts: kilos per room per cycle. The figure was correct and hid nothing. It simply did not answer the question she was actually asking.

How a cycle is built

Button mushrooms come in flushes.

The compost is spawned, it goes through incubation, and then the mushrooms arrive in three tides with gaps between them. The first flush is the most generous; after that the substrate wears out.

That is 44 days and 7 000 kg from a room.

Seven tonnes out of one room in a month and a half is the benchmark the trade measures itself by. Olha held it for years and was sure she was doing everything right.

Why incubation is the longest stage

For eighteen days the room is occupied and there is no crop at all. The mycelium spreads through the substrate, and there is no way to hurry it: raise the temperature and you get competing mould rather than faster growth.

That is exactly why growers guard every day after incubation. It has already been paid for with eighteen empty ones.

And out of that logic grows the habit of taking the third flush. If the room stood idle for eighteen days, taking everything out of it afterwards feels only fair. The logic holds right up until you ask what the room would be doing instead.

Where the flushes come from

The mycelium does not give everything up at once.

It exhausts the feed zone by zone, and between tides it needs time to recover. So the crop comes out in steps, and each one is noticeably lower than the last.

Why three and not more

A fourth flush is technically possible, but by then it is hundreds of kilos of nothing but small caps. Even the processor will not take them, so the trade agreed to stop at the third.

Three is not a law of nature. It is a habit that formed back when compost was dearer and rooms were cheaper.

Why the third flush looks free

Because the compost is already paid for.

A hundred and sixty-two thousand hryvnias per room are spent on day one of the cycle. After two flushes the substrate is still alive, and another tonne can be taken off it. Not taking it feels like waste.

“Throwing out compost that is still cropping was almost a sin with us. The old growers looked at it as blasphemy.”

What is wrong with that tonne

Third flush mushrooms are smaller and hold their shape worse. They do not go to the fresh market: the processor takes them at 37 ₴ a kilo against 78 ₴ for the fresh grade.

So the last tonne is worth less than half of each of the previous six.

And the rest of it comes along with it:

• seven days with the room tied up by exhausted substrate
• picking at the same 11 ₴ a kilo, even though the kilo is twice as cheap
• one more day of clear-out, because there is more infection
• a higher risk of carrying flies into the next cycle

What a cycle brings

Let us count both versions through to the end.

Per cycle, three flushes give more. 26 000 ₴ more.

This is the figure most calculations stop at, and that is exactly why everybody takes the third flush.

The calculation is correct. The compost sits in it once, the picking is counted as it happened, nothing is left out. It simply answers the question “what will this cycle give”, not the question “what will this room give”.

What this calculation never asks

How long it takes.

A cycle with three flushes is 44 days. A cycle with two is 36, because the clear-out after two flushes is shorter: fewer spores, less infection, less work.

The third flush adds eight days.

That is seven days of the flush itself plus one day of longer clear-out. Eighteen percent of the whole cycle goes on a tonne that fetches less than half the usual price.

Why the clear-out is longer

After a third flush the substrate is already infected — there is more mould in it and more flies. The room has to be washed longer and treated more thoroughly. That is five days instead of four, and that extra day belongs to the third flush too.

The room is the constraint

Olha has six rooms. Not six tonnes of compost and not six picking crews — six spaces, and there will be no more of them.

“I thought I was saving compost. What I was actually spending was the room.”

When the constraint is the space, you have to count per room-day rather than per cycle.

• three flushes: 242 000 ₴ over 44 days, which is 5 500 ₴ a day
• two flushes: 216 000 ₴ over 36 days, which is 6 000 ₴ a day
• a difference of 500 ₴ on every room-day
• in percentage terms, two flushes are 9.1% better

Per cycle three flushes win, per day they lose, and what the owner pays for is days.

What the third flush costs

Now both halves are visible.

Until then only the first was counted: what it brings. The second — what it takes up — was counted by nobody, because a room does not send an invoice for its own time.

It brings 26 000 ₴ a cycle. That is 3 250 ₴ for each of the eight days it occupies.

Those same eight days in a fresh cycle would have given 6 000 ₴ a day, so 48 000 ₴.

The difference is minus 22 000 ₴ a cycle. A day of the third flush brings in 1.85 times less than a day of a new cycle.

Multiply that by eight cycles and by six rooms — you get 1 056 000 ₴. And on top of that comes another 288 000 ₴: eight days of idle time for every room, which on two flushes disappear altogether. Together that makes 1 344 000 ₴.

Nobody stole this money and nobody made an arithmetic error. It was simply written down nowhere.

“At first I did not believe it. I redid it on paper, then in a spreadsheet, then asked my daughter to count it separately. All three times it came out the same.”

What this gives over a year

A room works 360 days a year.

Divide by 44 and you get eight cycles and eight idle days with nowhere to put them. Divide by 36 and you get exactly ten cycles with no idle day at all.

Dropping the third flush gives 1 344 000 ₴ — 45.2% more profit.

The margin rises from 12.3% to 15.4% along with it. Fixed costs did not move at all: the same people, the same cooling, the same building. The only thing that changed is how many times a year each room runs a full cycle.

The strangest line in that table

There are more mushrooms.

Three hundred and sixty tonnes instead of three hundred and thirty-six. Twenty-four tonnes more from the same six rooms, with the same people and without a single new space.

And these are fresh-market mushrooms, not processing grade. In money the difference is even sharper than in tonnage: revenue rose by almost four million against the same fixed costs.

How that works out

Every cycle without a third flush gives fewer mushrooms than one with it. But there are now ten cycles instead of eight, and the two extra ones bring six tonnes each.

Per room, twelve tonnes of first and second flush cover eight tonnes of third — and they cover them with fresh-market mushrooms rather than processing grade.

Turning the room over faster yields more product than squeezing the substrate dry.

What was tried before

“Twenty-four tonnes. I did not grow them — I stopped losing them.”

The first attempt was about making the third flush better.

Olha changed the watering regime, gave the substrate a longer rest between flushes, tried extra feeding. The third flush yield went up from 1 000 to 1 200 kg.

That really is a plus: the contribution of a cycle grew to 247 200 ₴ per room, and over a year across all six rooms it added up to 249 600 ₴.

Why that turned out to be too little

Because 249 600 ₴ is 18.6% of 1 344 000 ₴, which is less than a fifth of what simply dropping the flush gave.

And the main thing: even an improved third flush gives 5 618.18 ₴ per room-day against 6 000 ₴ for two flushes. By improving it, Olha made the bad option slightly less bad.

Why this rule is not universal

All of it rests on the room being the constraint.

If what you are short of is not space but compost or pickers, the arithmetic turns over: then every kilo off an already paid-for substrate really does make sense, because you will not be starting the next cycle anyway.

• constraint is rooms: take two flushes and turn them over faster
• constraint is compost: take all three, you have nothing to fill the room with
• constraint is pickers: count contribution per man-hour, not per room-day
• constraint is sales: keep the third flush if the processor buys steadily

The question is not about flushes. The question is what exactly you are short of.

It is easy to check. Look at what stands idle more often: the room or the compost delivery. If a room stands empty even a week a year for want of substrate, your constraint is not the space.

For Olha the answer was obvious from the start: the rooms are there, compost arrives on a phone call, there are enough pickers. Nobody had simply put the question that way.

What changed in the work

Two more cycles per room means more spawning, more clear-outs, more picking peaks.

The picking crew now works more evenly: six rooms on a six-day offset give a steadier schedule than eight long cycles with holes at incubation.

There are twelve more clear-outs a year, and that is the only part of the work that genuinely increased. But each one is a day shorter and easier, because there is less infection.

“We now take compost ten times a year instead of eight. The supplier was surprised at first, then gave us a better price for the volume.”

Compost use went up too: ten cycles instead of eight means ten loads instead of eight. But the compost per cycle did not change, and each cycle's contribution is counted after it.

What if there were more rooms

This is the first question growers ask.

Building a seventh room means removing the constraint, and then the third flush stops costing you a lost cycle. But a room costs money, while switching the regime from three flushes to two costs nothing.

What to do first

First squeeze those 45.2% out of the six rooms you have, and only then work out the seventh. Otherwise you will build a space that runs on the same unprofitable regime.

What to watch every month

One figure is enough, and it is not the yield.

• hryvnias of contribution per room-day, for each room separately
• the actual length of the cycle in days, not the planned one
• the share of mushrooms that went to processing instead of fresh sale

If the third figure is rising while the first falls, you are feeding the processor at the expense of your own space.

None of them calls for new accounting. Contribution comes off the invoices, days off the room log, the processing share off the same invoices at a different price.

The hard part here is not the counting but starting to see a day as a unit. A kilo is more familiar, it sits in a crate and has weight. A day passes unnoticed, and nobody sends you a bill for it.

“The first month was frightening. You throw out live substrate and wait for the figures to tell you that you are not an idiot.”

Where to start

Take the last finished cycle and divide its contribution by the number of days the room was occupied.

Then take the third flush out of the revenue, take out its picking, take out eight days — and divide again.

If the second figure turns out to be bigger, you have just found two extra cycles a year in every room.

The money does not vanish — you simply do not see it

Mushroom growing looks like a business about compost and humidity. It is really about how many times a year each room gets through a cycle.

Olha did not have a yield problem. She had six rooms, each of which spent eight days a cycle working at half the price.

Three flushes give 2 976 000 ₴, two give 4 320 000 ₴ and twenty-four tonnes more mushrooms. Both figures are true, and between them lies the whole difference between a kilo and a day.

How to see this at your own farm

All the arithmetic above rests on one row the harvest log does not have: how many hryvnias of contribution a room-day yields. While the farm is measured in kilos per room per cycle, neither the 22 000 ₴ that the third flush destroys on every cycle nor the 24 000 kg that dropping it adds is visible. When the same data is collected automatically, the contribution per room-day is visible for each room separately — which is exactly why owners of small and medium businesses use Finmap: to see the financial picture rather than assemble it after the fact.

Read also

• Greenhouse growing: cost per kilo, not kilos per square metre
• Cold storage: an empty slot costs the same

Topic foundation: Management Accounting Explained: What It Is and Why Owners Need It