Mushroom growing
Practical Action
Mushrooms for cultivation
There are two main types of edible mushroom grown in Zimbabwe - the white button
mushroom (Agaricus Bisporus) and to a lesser extent oyster mushrooms (Pleurotus ostreatus).
Other species have also been successfully cultivated, including wild Reishi mushroom
(Ganoderma lucida). Under average conditions 50 to 70kg of Pleurotus strain of mushroom
can be produced from 100kg of substrate, over a period of a few weeks, and with optimal
conditions the yielded can rise to a 100kg.
There has been a great amount of research into
mushrooms and their cultivation in temperate
climates but relatively little on varieties suitable for
tropical climates although interest in this area is
growing. Many commercial mushrooms only fruit at
around 20°C and are therefore not suitable for
tropical regions. Suitable tropical stains are harder to
obtain but some commercial strains can be ordered
such as strains of Agaricus bitorquis that fruit at
28°C.
Figure 2: Oyster Mushrooms
(Plruotus ostreatus). Photo credit:
Practical Action Southern Africa.
In Zimbabwe the Chakohwa Voluntary Mothers Group mushroom growing venture started with
white button mushrooms but the project was forced to change as button mushrooms needed
horse manure in the substrate which was not available in their area so the project switched to
oyster mushrooms that can grow on locally available materials.
Where to get your mushroom spawn
Technical skills and a theoretical background are required to produce spawn and literature on
the subject is often hard to obtain. Spawn production must be done under sterile conditions
which is usually difficult for small farmers. Consequently spawn production is mainly done by
laboratories in research institutions and universities.
The amount of spawn needed is equal to 2% to 4% of the weight of the substrate. Rather
than weighing the substrate, which can be difficult with large amounts of material, the weight
can be estimated from its volume. 1m3 of substrate will weigh about 300 to 400kg.
Where to grow your mushrooms
Mushrooms should be cultivated indoors so that the growing conditions can be maintained at
their most suitable for the mushrooms. Temperature, humidity, uniform ventilation, carbon
dioxide and substrate moisture levels can be controlled to get the best results while unwanted
contaminants, moulds and sunlight can be kept away from the crop. Any small room with
ventilation and a cement floor can be used. It should be possible to close off the room to the
outside by shutting ventilation and doors. The interior should be arranged so that it is easy to
carry out complete cleaning at the end of each cropping cycle.
The mushroom house should be well insulated to maintain a steady temperature. Corrugated
metal roofing is not suitable, but concrete or clay tiles would be. Insulating materials such as
fibre glass wool or expanded polystyrene can be used.
Small rooms can be made from wooden poles with stretched sacking covering the frame. The
sacking can be covered with a wet cement and sand mixture that will produce a hard
protective skin. When the Chakohwa Voluntary Mothers Group started mushroom production
people were reluctant to take part, consequently the few people that were interested had to
build their mushroom production house. This was built in one member’s yard to ensure
security, but this brought about the challenge of ownership of the structure should the project
end.
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