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How to Grow Mushrooms from Spawn

How to Grow Mushrooms from Spawn

Mushrooms develop best at an even temperature of about 16°C (60°F). Below 10° (50°F) or above 24°C (68°F) the mushrooms will not grow. Spawn will survive frost and recommences when temperatures rise.

Do not freeze. Do not use paraffin heaters, the fumes produced have a detrimental effect on the mushrooms.

Preparing the Compost
Mushrooms grow on strawy horse manure or a straw supplemented with organic nitrogen, such as poultry manure, fish meal or dried blood. Manure containing sawdust or wood shavings is unsuitable.

20kg (45lb) of well-rotted compost is sufficient for 100g spawn, a bed of 0.5m².

Stable Manure
For 20 kg you will need about 4 good barrow loads of fresh strawy stable manure. Make your compost heap in an open shed or of similar protection. Make sure the compost heap is free of worms and invertebrates which will eat the spawn. Take care to wet the straw well, pile into a heap and pack down firmly. Soon the temperature in the middle of the heap will rise and become too hot to touch. To retain the heat and prevent the manure becoming too wet if it rains, cover with a polythene sheet.

Turn every few days, bringing the outside to the centre to ensure even fermentation and moisten any dry areas with water. Keep the stack covered. Repeat for 3-5 weeks. The compost is ready when it has become dark brown and has no offensive smell, the straw should break easily. Water should ooze out when a handful of the compost is squeezed.

Get baled straw and wet thoroughly with a hosepipe over a period of 3-5 days. Once wetted, cover with polythene sheets to encourage a rise in temperature. When this has occurred, break open the bales, spreading it out in 15cm (6ins.) layers, adding more water if necessary.

To compost the straw, incorporate an activator of organic nitrogen, 5% Poultry litter or 2% dried blood, on top of each 15cm (6ins.) layer. Trample the straw as stacking proceeds, so that it is compressed and
consolidated. The heap will get hot and should be turned and restacked as described for stable manure.

Mushroom Beds or Boxes
A cellar, shed, garage, cold frame or under the greenhouse staging are all suitable places to grow mushrooms.

The compost should be 25cms. (10ins.) deep for beds and 20cms. (8ins.) for boxes. Add 25gms gypsum per kg of compost. Pack boxes tightly with compost. Ensure that the compost does not heat up after being made into beds or boxes, it must not be any higher than 20C° (60°F).

Scatter the mushroom spawn over the surface and mix in until it is 2 or 3ins. Deep. Firm the surface down again and cover with damp newspaper to keep the compost dark and moist. In two or three weeks thin white threats will grow.

When the compost is fully colonised remove the newspaper. Cover the compost with 2.5cm (1inch) of casing. Casing should be either: 45% garden soil, 45% peat or peat substitute and 10% chalk. OR: 90% peat or peat compost and 10% chalk.

Before using the casing, wet it thoroughly and allowed to drain. Keep it moist but not wet and water using a fine rose on the watering can or better use a mist sprayer. Mushrooms start to appear as tiny pins after 3-5 weeks from casing. Keep air humidity high (85% is ideal) to help mushrooms to develop. They grow in flushes. Pick by twisting the cap until the mushroom comes away. Remove any damaged and broken stems and fill the holes with casing.

We also do a selection of Mushroom kits, so if you want to try growing mushrooms in a more convenient way take a look what is available.

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One thought on “How to Grow Mushrooms from Spawn”

  1. tim says:

    You want to stelize the container they give you, with bleach or rubbing alcohol 70% (inner and outer).
    green mold will ruin the substrate if you dont.

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