Q: What are the ‘grow-your own’ blocks made from?

Q: What makes the mushrooms organic?

A: The cultivated ingredients for the block, the bran and the grain spawn, have to come from certified organic sources. These and the other materials in the block and the methodology have been checked and approved by the Scottish Organic Producers Association (SOPA)

Q: How can we dispose of the cardboard box the block came in?

A: The best way to dispose of the box is probably to compost it. The cardboard and inks are fully compostable.

Q: Is this a special bag

A: Yes, it is a bag made specially to make blocks for growing fungi in this way. It is made from polypropylene which can withstand the high temperatures used – under pressure – when the mixture is sterilised for 2 hours at 125 degrees C.

The small white ‘patch’ is a material similar to gortex which allows gases to pass through (e.g. oxygen and carbon dioxide) but allows no water vapour or micro-organisms through. This is important as the bag is sealed after sterilisation and inoculation to keep it sterile, but it must also remain moist for the mushrooms to grow.

Q: Why is the block white?

A: As the ingredients for the block are mainly oak shavings and hardwood chips the mixture goes dark brown after sterilisation.

However, once the mixture is inoculated, the mushroom mycelium (like the roots of the fungi) quickly colonise the block and start to digest the cellulose in the wood.  As the mycelium are white this turns the mixture white and also binds the loose particles together into a block.

Q: Why is the colour changing from white to dirty brown as it gets older

A: Around 5-6 weeks after inoculation the mycelium starts to form its own fake bark on the outside of the block. This is quite normal and is to be expected. Eventually, usually by the time the block reaches its second fruiting, the entire outside of the block will be a dark brown colour.

Q: How do I keep the block warm and moist during incubation?

A: The most important thing is to keep the block out of draughts and direct sunlight. The block should go into a cardboard box somewhere warm, with a tray of water in the bottom and some cling film over the top to help to keep it moist.

Q: Does the block need to be kept in the dark?

A: No. Unlike button mushrooms that grow on compost and need the dark, these saprophytic mushrooms (mushrooms that use wood as their food source) need normal levels of light, particularly during the stage where the block is fruiting.

Q: Is there any chance that a different type of mushrooms could grow?

A: No. The substrate of shavings, wood chips, bran and gypsum is thoroughly sterilised before being inoculated with an approved strain of organic spawn. Only the type of mushroom that is indicated on the box can grow from the block.

Q: Does the block produce mushrooms steadily and continuously?

A: For oyster and lions mane, the mushrooms are produced now and then over a period of a few months.

For shiitake the block produces ‘fruitings' or ‘flushes' as they are known, at regular intervals and which are initiated by your ‘shocking' the block. After a fruiting a block is left to rest for 4-6 weeks during which time the mushroom mycelium continue to digest the cellulose building up mushroom ‘pressure' or ‘potential' as we like to think of it. This ‘pressure' is released by soaking the block in cold water for a day or two with new mushrooms appearing pretty much all at once around a week later.

You should be able to get around 4-6 fruitings from each block, but the quantity does decrease over time as the amount of cellulose / food for the fungi decreases. It will up to you decide for how long you continue, weighing up the amount of time involved with the amount of mushrooms produced at each fruiting.

Eventually, after perhaps 6-9 months of regular fruitings, you may feel that it is time to dispose of your block. Broken up it can be put on the compost heap, or used as a mulch. You may find mushrooms growing outside where you have disposed of the block!

Q: At what stage should I harvest my mushrooms?

A: Ideally you should harvest the shiitake mushrooms (cutting at the base just above where the mushroom comes out of the block) when the margin (the outside edge of the cap) has broken away from the mushroom's stem / stalk. The mushrooms will stay in a good condition for longer if harvested at this stage. If the mushrooms are harvested when the top has opened out fully to be almost flat, it is still fine to eat, but will not store as long.

The speed of the mushroom's growth will depend on the temperature you keep the block at while it is fruiting. If warm (over 20 degrees C) they can grown very fast so you'll need to keep an eye on them, checking at least daily, to ensure that you harvest them at the optimal time.

With oyster mushrooms they should be cut at the base of the stem when it seems they are not growing any bigger. For lions mane usually twisting the mushroom will be enough to remove it, or use a sharp knife being careful not to get any of the bag too. These mushrooms do not keep for as long as shiitake and are better eaten soon after harvesting.

Q: What is the best way to store the mushrooms?

A: The mushrooms should be put into a well ventilated container or brown paper bag in your fridge as soon as they are harvested. A temperature of 1-3 degrees C is best. At this temperature the shiitake should stay in good condition for 1-2 weeks. Oyster and lions mane are best consumed within a few days.

Q: Do you know any good recipes for my mushrooms?

A: Yes, we have some good ideas for using your mushrooms but it is hard to beat just quickly frying them in some butter or olive oil! For other ideas see our recipes page.

Q: Are there any health benefits from eating these mushrooms?

A: Yes, innumerable health benefits are claimed for many species of mushrooms, with shiitake being one of the most valued.

Shiitake mushrooms have four to ten times the flavour of common white button mushrooms. In addition to their robust/pungent, woodsy flavour and meaty texture, they provide high levels of protein (18%), potassium, niacin and B vitamins, calcium, magnesium and phosphorus. They have natural antiviral and immunity-boosting properties and are used nutritionally to fight viruses, lower cholesterol and regulate blood pressure. Lentinan, an immuno-stimulant derived from shiitakes, has been used to treat cancer, AIDS, diabetes, chronic fatigue syndrome, fibrocystic breast disease, and other conditions with impressive results. Researchers S. Suzuki and Oshima found that a raw shiitake eaten daily for one week lowered serum cholesterol by 12%.

The basis of the mushroom's impressive health properties are complex carbohydrates called polysaccharides that build the immune system. According to mushroom researcher and cultivator Jeff Chilton:

'These compounds have been the primary focus of research due to their ability to inhibit tumours in laboratory test animals. Mushroom polysaccharides act by enhancing host defences rather than directly killing tumour cells. For this reason they are called host defence potentiators (HDP'

The specific effect of these polysaccharides is the activation of macrophages and T-lymphocytes, stimulation of interferon (a cellular protein produced in response to infection which acts to inhibit viral growth), and the overall enhancement of cell-mediated immune response. They have no toxic effects on humans, and are clinically safe.

For further information see
Shiitake Mushroom Log
Cancer Research UK