2Substrate

Pasteurised straw

Masters Mix

Supplemented sawdust

CVG

Hot-water or lime-bath pasteurisation; no pressure cooker needed.

3Amount

Bags

Substrate weight

I have spawn

Number of bagspcs Substrate per bagkgwet, without spawn

Recipe settings

Spawn rate%% of wet substrate weight Target moisture%% of wet weight

Pleurotus pulmonarius

Summer oyster

also P. ostreatus var. florida; Phoenix, Italian, sajor-caju

beginner

Substrate: Pasteurised straw · recommended

Dry rye706 gfor the grain spawn

Spawn1.2 kg10% of substrate weight

Wet substrate12 kgfrom 4.67 kg of dry straw

Bags4 × 3 kgplastic, perforated

Materials

Item	Amount
Grain spawn (colonised rye)from 706 g of dry rye (× 1.7 after soaking and simmering)	1.2 kg
Wheat straw, dryabout 12 kg after pasteurising	4.67 kg
Hydrated limeonly for the cold lime bath	about 3 g / L of water
Plastic bagsabout 3 kg of substrate each	4 pcs

Preparation

Rye grain spawn

2–3 weeks ahead. Bought grain spawn replaces this stage.

Weigh 706 g of dry rye, soak 12–24 h and simmer 10–15 min.
Drain and let the surface dry. This gives about 1.2 kg of grain.
Fill jars or filter patch bags and sterilise 90–120 min at 121 °C (pressure cooker, 15 psi).
Inoculate and keep at the colonisation temperature until fully colonised.

Other grains, jars and electric cookers: grain spawn calculator

Substrate

on spawning day

Chop the straw into 5–10 cm lengths.
Pasteurise: submerge in water at 70–80 °C for about 1 h, or soak 18–20 h in cold water with about 3 g of hydrated lime per litre.
Drain to about 65% moisture: a hard squeeze gives a drop or two at most.
Cool below 30 °C. Fill 4 bags with alternating layers of straw and spawn: about 3 kg of substrate and 300 g of spawn per bag.
Close the bags and punch holes every 10–15 cm.

Conditions

Phase	Temp.	RH	Light	Duration
Colonisation	25 °C	80%	—	12–16 d
Pinning	22 °C	92%	12 h · 500–1000 lx	4–6 d
Fruiting	22 °C	88%	12 h	5–7 d
Between flushes	22 °C	85%	12 h	7–10 d

Temperature: safe at 12–30 °C; critical below 5 °C and above 34 °CFlushes: 3–4First harvest: 3–4 weeks

Mid-range values that suit most strains. Your supplier’s strain sheet takes precedence.

Notes

The most forgiving oyster: fruits at 20–25 °C with no cold shock.
'Florida' strains fruit up to about 25 °C; sajor-caju likes it warmer.
Oysters shed heavy spore loads: pick before the caps flatten and keep them out of the bedroom.

MEA

Malt Extract Agar

Agar10 g20 g per litre

Nutrients10 gdry malt extract

90 mm plates20–2520–25 ml each

Sterilisation40 min15 psi (121 °C)

Materials

Item	Amount
Water	500 ml
Agar powder (E406)20 g per litre	10 g
Light dry malt extractor about 13 g of liquid extract (syrup)	10 g
90 mm Petri dishes20–25 ml each	20–25 pcs

Preparation

Measure 500 ml of water, add the dry ingredients and stir. The agar dissolves during sterilisation.
Pour into a bottle or jar with room to spare. Cover loosely with foil or loosen the lid.
Sterilise 40 min at 15 psi (121 °C), timed from when the cooker reaches pressure; in an electric pressure cooker (0.7–0.8 bar), 65 min. The time is for 500 ml in one vessel.
After switching off, wait until the pressure is back to zero. Do not shake the bottle, or you get bubbles.
Cool to about 50 °C (46–52 °C). Hotter agar warps plastic dishes.
Pour in clean conditions (still-air box or flow hood), 20–25 ml per dish.
When the agar has set (about 30 min), close the dishes and wrap the edges with Parafilm.

Notes

Another common variant: 30 g malt and 20 g agar per litre; some recipes add about 5 g peptone or 20 g dextrose.
Dry malt extract is sold in home-brewing shops.
Yeast (2 g/L) and peptone (1 g/L) add nitrogen and vitamins. MEA with both is MYPA.
The time depends on the liquid in one vessel: up to 100 ml 25 min, 250 ml 30, 500 ml 40, 1 L 45, 2 L 55. In an electric pressure cooker: 50, 55, 65 and 75 min; split more than 1 L into several vessels. Add 10–20 min when the vessels stand close together.

Secale cereale

Rye

6 × 1,000 ml · Soak and simmer

Dry grain1.73 kg288 g per jar

Drained weight2.92 kgcheck weight; 487 g per jar

Gypsum17 g1% of the dry grain

Sterilisation90 min15 psi; electric 225 min

Materials

Item	Amount
Dry grain (rye)288 g per jar, about 40% of its volume	1.73 kg
Gypsum1% of the dry grain	17 g
Jars with filter lids1,000 ml each	6 pcs

Batch

Hydrated grainthis is your spawn weight: 2.92 kg
Moisturedry grain taken at 12%: 48%
Dry grain in the jarof the jar volume; about 2/3 after hydration: 40%

Work out the substrate for 2.92 kg of spawn

Preparation

Weigh out 1.73 kg of dry grain and rinse it until the water runs clear.
Soak for 12–24 h in cold water.
Simmer 10–20 min, until the grain is soft but not split. Drain and spread it out until the surface turns matt.
Weigh it: the grain should come to about 2.92 kg. If it weighs less, simmer longer; if more, let it dry a little.
Mix in 17 g of gypsum and fill the jars, about 487 g per jar: they end up about 2/3 full, with room to shake. Close them with filter lids.
Sterilise 90 min at 15 psi (121 °C), timed from when the cooker reaches pressure; in an electric pressure cooker (0.7–0.8 bar), 225 min.
Let them cool to room temperature and inoculate in clean conditions (still-air box or flow hood).

Notes

Grain density varies: weigh 1 litre of yours and enter it under the settings.
When the containers fill the cooker floor tightly, add 15 min.
At about 300 m above sea level add about 10% to the time, at 650 m 25–30%.
A pot without pressure (100 °C) does not sterilise grain, however long it boils.

How much grain and substrate your grow needs

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Preparation

Rye grain spawn

Substrate

Conditions

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Preparation

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Materials

Batch

Preparation

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