Mushrooms need shade, moisture and fresh air rather than strong sun. A cool greenhouse corner can work well, but only if you manage heat, humidity and airflow locally.
Mushrooms are not the first crop most people think of growing in a greenhouse, but the right corner can suit them surprisingly well. Unlike tomatoes or cucumbers, they do not need strong sun. What they need is a sheltered place with indirect light, steady moisture and enough fresh air.
For UK gardeners, that makes a greenhouse particularly useful in the cooler parts of the year, when a shaded bench or the space beneath staging can become a separate growing zone for oyster mushrooms and other suitable varieties.
Where Mushrooms Fit in a Greenhouse
Start with the parts of the greenhouse that stay out of direct sun: beneath staging, under a bench or along the north side. These cooler pockets are often easier to manage than the main growing area.
The aim is not complete darkness. Many gourmet mushrooms, including oyster mushrooms, need some light to develop normally, but direct sun can dry a fruiting block quickly.
The catch is heat. On a sunny day, even a mild British spring can push greenhouse temperatures well above the range preferred by many kits. That is why growing mushrooms in a greenhouse is often easier in spring and autumn than in the hottest part of summer.
What Conditions Do Greenhouse Mushrooms Need?
There is no single temperature or humidity figure that suits every mushroom. Oyster, shiitake and lion’s mane all have different fruiting ranges, and even oyster strains can be sold for cooler or warmer conditions.
For a home grower, the instructions supplied with the spawn or grow kit should be the starting point.
Three things matter across most varieties:
- Shade and indirect light. Keep the block out of direct sun, but do not assume mushrooms need total darkness.
- Humidity. Fruiting mushrooms need a moist environment. Mist the block or immediate growing area as directed rather than trying to keep the entire greenhouse permanently damp.
- Fresh air. Mushrooms release carbon dioxide as they grow. Poor airflow can lead to long stems and small caps, particularly with oyster mushrooms.
A shaded corner should therefore be humid, but not sealed or stagnant.
Best Mushrooms to Grow in a Greenhouse
Oyster mushrooms are the easiest place to start. They are widely available as ready-to-fruit kits, grow relatively quickly and are more forgiving than many specialist varieties.
If you are using an unheated greenhouse, choose the strain for the season rather than buying by colour alone. Cooler-weather oysters suit spring and autumn, while warmer strains cope better as temperatures rise.
Lion’s mane can also work if the greenhouse stays within the range recommended for the kit and there is enough fresh air. Shiitake can be grown from prepared fruiting blocks, although it is slower than oyster mushrooms.
Button mushrooms prefer a compost-based growing medium and are a different growing setup. For a first attempt, oyster mushrooms are usually simpler.
Can You Grow Mushrooms in an Unheated Greenhouse?
Sometimes, yes.
An unheated greenhouse is not automatically warm enough in winter or cool enough in summer. What matters is the temperature around the fruiting block.
Spring and autumn can be useful because the greenhouse is protected from wind and heavy rain but cooler than the house. In summer, overheating becomes the bigger risk. In deep winter, growth may slow or stop if the greenhouse falls below the variety’s preferred range.
A small thermometer beside the mushroom block is more useful than guessing from the weather outside.
Using a Mushroom Grow Kit in a Greenhouse
For most beginners, a ready-colonised mushroom grow kit is the simplest route.
Place it in a shaded position, follow the kit instructions for opening or cutting the bag and keep the exposed area hydrated. Check it daily during fruiting because a greenhouse can change quickly from cool and humid in the morning to hot and dry by afternoon.
Do not automatically mist the whole greenhouse. High humidity may suit mushrooms, but it can also encourage disease on some greenhouse crops. Keep the mushroom microclimate local.
If you are starting from spawn rather than a ready-to-fruit kit, colonisation is a separate stage and may need a more stable temperature. Starting the substrate indoors and moving it into the greenhouse for fruiting can be more reliable.
Fungi are the interface organisms between life and death.
Paul Stamets, mycologist
Common Problems
Direct sun and overheating can dry a grow kit quickly, so shade comes first.
Dry or cracked mushrooms usually point to low humidity. Long stems and small caps, especially on oyster mushrooms, can point to insufficient fresh air.
Green mould, unpleasant smells or unusual contamination are a reason to isolate the block from other kits rather than leaving it beside your crops.
Can Mushrooms Share a Greenhouse With Vegetables?
Yes, as long as you treat mushrooms as a separate growing zone.
Keep them beneath staging or on a dedicated shelf where misting will not soak tomato or cucumber foliage. Leave enough airflow around the area and remove spent substrate when the kit has finished producing.
This is where greenhouse mushroom growing becomes useful. Mushrooms can turn a shaded area that is poor for sun-loving crops into productive growing space without competing for the main beds and benches.
So, Is a Greenhouse Good for Growing Mushrooms?
It can be.
A greenhouse is not automatically the perfect mushroom environment, but a cool, shaded corner can work well for oyster mushrooms and other suitable grow kits. Protect the block from direct sun, maintain local humidity and keep fresh air moving.
For UK gardeners, spring and autumn are particularly useful windows to experiment. The space beneath a greenhouse bench can become a small second growing zone for a crop that needs very different conditions from the tomatoes above it.
