Gourmet mushrooms are expensive to buy because they are perishable, hand-picked and slow to get to a shop. None of that applies on your kitchen bench. The question is what the inputs cost per kilo of mushrooms, and the honest answer depends on which method you use and how many flushes you get. The numbers below use our shelf prices and typical hobby yields; your room and your culture will move them, but not by enough to change the conclusion.

The yields to expect

Hobby growers talk about biological efficiency: fresh mushroom weight as a percentage of dry substrate weight. On a well-run coir tub of oysters that is commonly 50 to 100% across two flushes. In plainer terms, a 5kg bag of hydrated coir-based substrate spawned at 1:2 with 2.5kg of grain usually gives 1 to 2kg of oyster mushrooms over its life. A 2kg hardwood block of lion's mane gives 400 to 800g. A 2kg all-in-one gives 300 to 700g of oysters. Kits sit around 150 to 400g on the first flush.

Method by method

All-in-one bag

A 2kg all-in-one plus a culture syringe lands at roughly $90 to $100 delivered. Against 500g of oysters that is about $190 per kilo: dear per kilo, cheap as a first lesson and a few dinners.

Bulk grow, coir tub

One 2kg sterilised grain bag, one 5kg CVA substrate bag and a culture come to around $185 plus shipping, call it $215 delivered. At 1:2.5 that is a full 50 to 60 litre tub. Against 1.5kg of oysters over two flushes, that is roughly $145 per kilo on the first run.

Bulk grow, second run

Here is where the maths turns. The culture is a one-off, and a colonised grain bag can be expanded grain-to-grain into fresh sterilised bags, so the second tub costs only the grain and substrate: about $155 plus shipping for the same 5kg tub, and under $100 if you run 1:4. Against the same 1.5kg that is $65 to $105 per kilo, and the hardware (tub, still air box, mister) has already been paid for.

Lion's mane on hardwood

A 2kg wood lovers substrate bag at $30 spawned at 1:5 with 400g of grain, roughly $45 of inputs per block once the grain bag is split across blocks. Against 600g of lion's mane over two flushes that is about $75 per kilo for a mushroom that retails at $50 to $80 when it is available at all.

What moves the number

• Spawn ratio. 1:4 halves your grain cost against 1:2 but colonises slower, which raises the contamination risk. The ratio guide explains the trade.
• Flushes. A second flush is free mushrooms. Rest the block, soak it, and you lift yield 30 to 50% for nothing. Harvest guide.
• Expansion. One grain bag expanded into five is the biggest lever of all. Colonised spawn guide.
• Contamination. One lost tub doubles the cost of the next. Clean technique is the cheapest input you have.
• Shipping. Bigger orders ship cheaper per kilo. See delivery.

Is it worth it?

If the question is purely financial, a repeat bulk grow of oysters or lion's mane beats shop prices comfortably, and the gap widens as you get better. If the question is whether a first all-in-one is worth it, the answer is yes for a different reason: it tells you whether you want to do this, for the price of a couple of restaurant meals.

Written by the Aus Myco Kingdom crew. Everything here is general growing information for gourmet and medicinal species; your room, your climate and your culture will have the final say.