Mushrooms reproduce through spores. A mushroom is capable of producing and dispersing billions of spores.  These spores produce thin, finely branching threads which are called mycelium.  We refer to this as mushroom spawn (a substance– or carrier – like grain that has been inoculated with mycelium).

Spawn

The compost used as a substrate for mushroom growing consists of a special mixture of straw-rich horse manure, straw, chicken manure and gypsum. Mixing these ingredients in the right proportions will result in fresh compost.  The resulting compost is then pasteurised to make it suitable for mushroom growing.

Grains inoculated with mushroom spawn are then mixed through the pasteurised compost.  This spawn develops finely branching fungal threads (mycelium). After a few weeks the compost is completely colonised by this mycelium and is ready for delivery to the mushroom farm.

A mushroom farm comprises a number of growing rooms. A growing room is a hermetically sealed room that contains four to five tiers of beds (shelving) on both sides of an access aisle. The beds are filled with compost, then covered by a layer of casing soil (a type of peat).  The mycelium continues to grow upwards from the compost through the layer of casing soil.

Casing soil

Approximately three days after filling, the grower initiates a significant climate change in the growing rooms.  The compost temperature is reduced from 27° C to 20° C over a period of two to three days.  High volumes of fresh air are introduced into the growing room and the humidity drops sharply. This effectively creates autumn conditions in the growing room. This change in the ambient climate is necessary to stimulate the natural process of mushroom development.  Influenced by this climate change, the mycelium grows through the upper layer of casing and starts to form small pinheads that will develop into mushrooms.  The response of the mycelium is natural as it wants to reproduce before the cold winter sets in.  The mushrooms will in turn produce more spores (a kind of seed) which the mycelium uses to reproduce.

About three weeks after the beds have been filled and cased, the first crop – or flush – of mushrooms can be harvested.  A week later the second flush appears on the beds.  Two flushes of white mushrooms are usually harvested in a cropping cycle.  Brown chestnut mushrooms are sometimes harvested in three flushes.

All mushrooms destined for the fresh market are picked by hand by trained pickers.

Exotic mushroom varieties, for example oyster mushrooms or shiitake, are either cultivated commercially in the Netherlands or imported.  These mushrooms are grown on pasteurised substrate (a growing medium).   The composition of this compost differs to that used to grow common mushrooms. Sawdust is one of the ingredients used to make substrate suitable for cultivated exotic mushrooms.

After pasteurisation, the substrate is inoculated with special spawn. Plastic bags or bottles are then filled with this substrate, and left for mushroom development to begin. Just like common mushrooms, exotic mushrooms are picked by hand. Some of these varieties, such as oyster mushrooms, grow in clusters.

Some varieties of edible mushrooms are gathered in the wild because they are very difficult to grow under commercial conditions. These are generally the varieties that grow on trees or bark; so-called mycorrhiza-formers. The best-known mushrooms gathered in the wild are ceps, truffles and chanterelles.

These mushrooms are picked in autumn. To secure year-round deliveries, we follow the seasons and source our mushrooms from the part of world where autumn is at that moment.

The harvested mushrooms are graded and selected for quality in accordance with customer specifications before they are transported in refrigerated vehicles to Banken. Depending on the season, the Banken Champignons range offers dozens of different forest mushrooms.