How to profit from growing oyster mushrooms

Hanging individual spawns on ropes reduces disease spread and allows mushrooms to sprout from all angles. PHOTO | ABDUL-NASSER SSEMUGABI

What you need to know:

  • Mushrooms are a highly recommended food because they are low in carbohydrates yet rich in fibre, vitamins, minerals, among other nutrients.

Last December, Zurah Nakalema’s first season was flourishing with oyster mushrooms shooting from all angles of the spawns.

“Neighbours and friends were asking me to teach them how to do it and buyers were commending me for the quality,” she recalls.

Then she started seeing some brown dusty textures. Other spawns grew a greenish black colour while others oozed a thick and slippery liquid.

“Soon, my farm started producing a strange smell. I reported to my supplier, as he had advised me, prior but he came about two weeks later and the infection had spread out of control.”

The supplier replaced only 20 of the 100 spoilt spawns and Nakalema, like many inexperienced mushroom farmers, wanted to give up. But after a second try, the diploma in journalism graduate now takes mushroom farming as a serious vocation.

There are more than 14,000 types of mushrooms, some poisonous, some edible and delicious. Shiitake, sold at $25 (Shs87,600) per kilogramme, is the most profitable type, but the oyster mushroom is the most popular.

In Uganda, however, the relatively low production coincides with low consumption. But those who have ventured into mushroom growing find it interesting despite the challenges.

Stage one: Making grain spawn

The most complicated procedure in mushroom growing is developing the mycelium or the mushroom seeds. Livingstone Bbosa, the manager of Ssekubunga Mushroom Growers in Makindye-Luwafu, says the process begins by tapping the mushroom spores from the gills inside a mature mushroom cap.

Place the mushroom with the gills face down onto a piece of paper and cover it with a glass. After 24 hours, remove the glass and gently lift the mushroom. Then seal the spore print in a bag and keep it in a cool, dry, dark place until you are ready to cultivate.

Cultivation involves creating a spore syringe, where the spores are re-hydrated using sterile water and then used to inoculate the growing medium such as wet sawdust or grain to develop. This is done in a dark room because spores do not need light.

To make the growing medium, you need grains such as wheat, rice, or even popcorn. In Uganda, the more affordable grains are millet and sorghum, a kilogramme of which goes for Shs25,000 wholesale price. The grain must absorb and retain water and be rich in nutrients to feed the mycelium. After choosing the grains, rinse and clean them, then soak them in water for 12-24 hours.

Cook the grains for 15-20 minutes so that they absorb water but ensure they do not crack open, which could increase the risk of contamination during incubation. Drain and dry excess moisture on the outside of the grains while ensuring they retain enough moisture inside.

Then put the grains in mason jars or glass bottles, about 2/3 or 3/4 full, stuff the bottle opening with synthetic pillow fibre or cotton wool.

In the case of a jar, dig a hole through the lid to fit the cotton to stop contaminants while allowing the mycelium (the fungus that produces mushroom) to breathe. Before boiling or sterilising the grain, you should cover the lids with tinfoil to prevent water from the pan or pressure cooker from spilling into the grain which could change the moisture content of the jar. Now sterilise them for 90 minutes at 15 PSI or 121°C or 250°F.

After cooling, the grains are ready to be inoculated with the developed spore hence forming a spawn.

Sekubunga Mushroom Growers prepare thousands of spawns before supplying them to out-growers.

When the mycelium or fungus spreads in the whole bottle, Bbosa says, it can produce 15 such bottles, with each bottle producing 15 spawns that will fruit in three weeks.

Stage two: Mixing mycelium

This stage avoids the complex laboratory procedures above. Rather, farmers buy the already developed mycelium from suppliers such as Ssekubunga and distribute it into their spawns.

Here, Bbosa says, you need cotton husks (a sack of 50 kilogrammes is sold at Shs60,000), water, a room for mixing substrate and of course labour.

Soak the husks in a drum of about 100 litres of water. You can use lime to reduce acidity in the cotton husks.

After a day, lay the husks on a flat surface and cover them to drain the excess water but retain moisture inside. After three days, then pack them in polythene bags. Boil the husk bags for about six hours at a very high temperature and an additional two hours.

You can borrow Bbosa’s simple trick:  of placing a raw sweet potato on top of the bags. When it is tender enough to be eaten, your husks are also ready.

Then take the boiled husks to the planting room soon enough before they get exposed to mold.

The planting room must be well insulated and whoever accesses it must be disinfected first.

After introducing the mycelium to the bags, cover them with a casing layer, usually newspaper cuttings, which allows just enough air for germination and retains the moisture inside.

In about two weeks, the mushrooms can start shooting through the newspaper casing or from wherever if you poked the bags with some small holes.

Stage three: Preparing spawns

Most growers prefer skipping the hectic procedures in stages one and two and buy the prepared spawns ready to sprout. Here, regular irrigation is the must-do. But still, you must book for your spawns three weeks prior the same time the supplier needs to make the spawns ready.


Meanwhile, prepare your structure. A 10ft long, 10ft wide and 15ft high structure can accommodate about 500 spawns. You need about 50 wooden poles to make the ceiling, and the layers on which the spawns will sit. The poles should be spaced by an arm’s length for easy watering and harvesting. However, Nakalema, a grower in Kitende, prefers hanging the spawns on ropes because it separates each spawn, allowing the mushrooms to sprout from all angles, which gives her better yields.

She adds that although that spacing requires watering every individual spawn, by avoiding inter-spawn contact it minimises the spread of disease. If you are building a new structure it must be made of wood or papyrus. But even if you are manipulating a brick-made structure, the ceiling must be made of plywood or the cheaper papyrus to maintain the coldness.

Cover the floor with charcoal dust or sand to absorb the water that drips during irrigation and where necessary, scoop the water away to maintain hygiene.


Mushrooms need natural light but not direct sunlight as it will increase the temperatures and reduce the moisture in the spawns, hence hindering the germination. So, Bbosa advises that, the light inlets of your structure should not face direct sun rays.

You must also disinfect the structure, at least a week before you introduce the spawns, to rid it of any existing contaminants. Bbosa recommends Norocleanse, a disinfectant that has also been widely used in the battle against Covid-19.

“By the time we deliver the spawns, they are almost ready and after just a few days of watering they must start sprouting,” Bbosa says, recommending three irrigation phases a day, sometimes four when the weather is too hot.

Watch out for infections

Two weeks after Nakalema’s first season suffered a setback, her supplier told her that her farm had suffered from infections. They are usually caused by “contaminants” or the unwanted fungi, bacteria, or insects which compete with the mushrooms for the same nutrients. In some cases they eat the mushrooms and the mycelium thus hindering germination, growth and mushroom quality. They are common because they can be spread by air currents, farm tools, such as cutters, sprayers, the substrate, flies, mites or insects, or the farmer themselves. The fungi or mold can happen at any stage in green, black, yellow, or mixed colours, depending on the cause.

For instance, failure to kill all the germs while boiling the substrate might cause a liquid in the spawn, which could later manifest in yellow mold, raise the temperature and bring rotting. The green mold, Bbosa says, can be caused by poor hygiene during incubation or at the growing stage while inadequate watering while soaking the substrate (the husks) makes it hard for the mycelium to easily colonise or spread, creating the black mold. For safety, suppliers must inspect the growers’ farms regularly. More so, Bbosa advises mushroom farmers to prepare well, be quick and efficient; practising high levels of hygiene, following a checklist of what-to-do, following steps, and cleaning between each step. Because spores move in air from anywhere, regular cleaning of all surfaces and tools with alcohol-based liquids such as ethanol and using gloves is highly recommended. You cannot save an infected jar because usually by the time you spot the mold, the spores have already spread. But if you detect it on your bulk grow early, you can spray hydrogen peroxide solution to the infected area to kill the contaminant spores, meanwhile allowing the mushrooms to mature. It is also better to discard the infected contents in a compost or trash bin.

Now in her third season Nakalema, out of experience and advice from her new supplier, is more observant and can identify potential symptoms of contamination early enough.

The money in mushrooms

Bbosa says the number of their out-growers is increasing steadily as more people find mushrooms a cheaper and easier substitute for poultry especially for urban farmers as they require less space, money and labour.

He adds that even the government has started incorporating mushroom farming in its wealth creation schemes by subsidising farmers. Ssekubunga sells each spawn at Shs3,000. Each can yield two kilogrammes in three months. You can sell a kilogramme of fresh mushrooms up to Shs12,000 depending on the market and season, but selling it at the minimum of Shs5,000, you will earn Shs10,000 from each spawn over three months.  Subtract the expenditure of about Shs4900 worth water, labour, rent and delivery fees, you make a net profit of Shs5100 per spawn. So 500 spawns will yield a profit of Shs2,550,000 around Shs850,000 per month.

Markets and seasons

Rainy seasons, when the temperatures are down, and mushrooms do not need frequent watering they usually yield bumper harvests, hence lower prices. And the reverse is true for sunny seasons.

The major markets for urban growers are Nakasero, Kibuye and Nakawa, restaurants and hotels. But Nakalema and Bbosa say your client could be your neighbour, at that stall where you buy vegetables, at your workplace, or anyone in your social network. “Many people fear to venture into the mushroom business because they think mushrooms are not popular,” Bbosa says. “But that is the gap you should exploit. Be the pioneer in your network, you will thank me later.”


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