06 Sep 2022 10:46

Cultivate autumn mushrooms in the greenhouse


Autumn is almost here which means that we soon can start to cultivate some delicious edible mushrooms inside or near the greenhouse. So, if you have room in your greenhouse this autumn, you can read about how to cultivate your own edible mushrooms.

Some may think that the greenhouse season is over, but you can still cultivate vegetables in autumn – and even different types of mushrooms such as oyster mushroom, Lion’s Mane and brown beech mushroom.


Below you will find a guide on how to cultivate edible mushrooms inside and outside the greenhouse.

Guide: Make your own mushroom grow bag for the greenhouse

A mushroom grow bag can for example contain hay which is grafted with the mushroom you want to cultivate. When you have made your mushroom grow bag, put it in the greenhouse and cut a hole in the bag. About 10 days later, you can harvest your greenhouse mushrooms. With ideal growing conditions, you can harvest mushroom for up to a year.

What you’ll need

  • Chopped hay
  • A large plastic box (100 litres or more) with a lid
  • A potato sack or jute sack
  • Calcium hydroxide
  • Gloves
  • A couple of heavy rocks or bricks
  • Alcohol
  • Large plastic bags
  • Mycelium of the mushroom you want to cultivate
  • Breathable adhesive tape

How to do it

  1. Your hay should have a length of 2-10 cm. If you have trouble finding the right length, you can chop it yourself by using a grass trimmer. Then you put the hay inside a potato sack or jute sack (with holes)
  2. Mix 1 dl of calcium hydroxide with 100 litres of water in the plastic box. Remember to use gloves. Place the sack with hay in the mixture. Push the sack down so all hay is covered and place a couple of rocks or bricks on top. Put the lid on.
  3. After 24 hours, pick up the sack and hang it to dry. You can, for instance, lay some boards on top of a wheelbarrow, so the water can drip into the wheelbarrow. Give the sack a little squeeze to get the rest of the water out. The hay should be damp, but not wet. If it is too wet, there is a bigger risk of mould contamination.
  4. Dump the hay on a clean surface that has been cleaned with alcohol. Mix the hay with mycelium and put it in some large plastic bags. Seal the bags and make horizontal cuts all the way around the plastic bag. Use breathable adhesive tape to cover the holes.    We usually use approx. 100g of mycelium (including the grain on which it is grown) per litre of hay. You can also experiment with less, but remember, the more mycelium you use, the faster it flows-through and the lower is the risk for contamination.
  5. Place the bags somewhere cool (16-18 degrees Celsius), and preferably a dark place in the greenhouse. Mushroom bags can also be wrapped in newspaper, so you are sure that it gets no sunlight. 
  6. Wait while the mycelium spreads. If you see that there are large areas where nothing happens, it is due to contamination. Remove the contaminated part.
  7. When the mycelium is all over the bag (it will look like a white net), it is time for the fructification process. Now you can move the bag to a lighter place in the greenhouse (but avoid direct sunlight) and remove the tape. If you have wrapped it in paper, remove the paper too when it is time for the fructificarion.
  8. When the first mushroom is fully grown, you can begin harvesting.
  9. Use normal tape to cover the holes and let the sack rest for 10-14 days, and then cut new holes. When the sack no longer grows mushrooms, you can either mix the mycelium with some new hay and make more sacks, or you can use it as compost and fertilizer for your plants in the greenhouse.


The ideal temperature is 18 degrees when you start the cultivation but avoid direct sunlight in the greenhouse. If you have snails in the garden, or do not have more room in the greenhouse, you can hang up the mushroom bags instead. This way you also avoid the snails eating the mushrooms. The older the mushroom grow bag is, the longer you must wait to harvest the mushrooms.


This guide is made in collaboration with Danish gartner Bendt Rossander from Fyns Ø Svampe.

Guide: Cultivation of mushrooms on logs outside the greenhouse

If you have logs in the garden, or are about to cut down a broad-leaved tree, then you can use the logs to cultivate your favourite mushrooms alongside the greenhouse where there is shade.

What you’ll need

  • Dowels (or small wooden sticks 8-10 mm in diameter) of broad-leaved tree. Ideally beech or birch
  • A log or tree stump (broad-leaved tree)
  • Mycelium of the mushroom you would like to cultivate
  • An old jar with a lid
  • Breathable adhesive tape
  • Hammer and nails (to make holes in the lid)
  • Alcohol
  • A bowl, a pot and a colander
  • Drill and drilling machine (8-10 mm)
  • Beeswax
  • Paintbrush

How to do it

  1. Let the dowels soak in a bowl with water in 1-2 days. Then boil the dowels for 20-30 minutes until they are pasteurized and soft. Let the dowels dry and wait for them to reach room temperature.
  2. With the hammer and nails, make holes in the jar lid. This way the mycelium can get oxygen. Thoroughly disinfect the jar with some boiling water or alcohol. Then put the breathable adhesive tape over the holes.
  3. Put the dowels and mycelium in the jar and make sure your hands are clean and avoid touching the dowels and mycelium too much. Put the lid on the jar and shake the jar until the mycelium and dowels are mixed. Then the jar is placed somewhere dark at room temperature.
  4. Wait 3-4 weeks. When the mycelium has spread as a white layer on the dowels, they are ready for use.
  5. Drill holes for the dowels all around the log or tree stump. The holes should be ½ cm deeper than the dowels, so there is space for oxygen. Make the holes wide so it is easier to get the dowels inside the wood. When all the dowels are in, the beeswax is melted in a water bath and are then in a thin layer applied with a paintbrush on the holes. If you drill at the top of the log or tree stump, then make the holes near the bark. If you are using a log, you can let it soak for 1-2 days before getting started. When the log or tree stump is grafted and ready, place it alongside the greenhouse where there is shade.
  6. Please have patience and wait while the mycelium has spread to all over the log or tree stump. If you are using a log, it is important to irrigate regularly (once a week) so it is always damp.
  7. The mushrooms are ready for harvest when the first mushroom is fully grown.


Put the grafted logs along the greenhouse and wait patiently. When cultivating in wood, it can take 1-2 years before you can harvest. On the other hand, the wood provides much more nutrition for the mushrooms than if you for instance had used hay or coffee grounds. Therefore, depending on the size of your tree stump, you could harvest delicious mushrooms for several years.


You can cultivate in pretty much any sort of broad-leaved tree, so feel free to use whatever you or your neighbour may have. If you choose to use a log, I will recommend a log that has a diameter of at least 10 cm and is 30-40 cm long. It is also a good idea to let a freshly cut log dry for 1-3 months before grafting. Alternatively, you can use an old and dry log with no mushrooms growing on it. If you are using a tree stump, I recommend grafting it within the first 9-12 months after it has been cut down. The fresher the wood is, the better. But an old tree stump can also be used as long as it is not decomposed.


In case you do not have any dowels, you can make them by cutting branches of for example beech and birch. You choose how many dowels you want to have in your log – but the more you have, the better it is. We usually use approx. 100g of mycelium (including the grain on which it is grown) for about 60 dowels, but less will do. It only means that you may have to wait a bit longer before they are ready to be grafted.


This guide is made in collaboration with Funga Farm (an urban farm growing organic and sustainable mushrooms).


Check out forum.tagtomat.dk/ for more inspiration. 


Have fun cultivating mushrooms!

Om TagTomat

Behind the Danish company TagTomat (in English ‘Roof Tomato’) is a skilled team whose passion is to create green communities and inspire to green do-it-yourself and do-it-together projects. Today TagTomat sells organic flower seeds and vegetable seeds, which are packaged with our seed packaging machines from 1895. It all began in 2011 in the heart of the neighbourhood Nørrebro in Copenhagen with just five self-watering plant boxes on a wheelie bin storage. You can read more about TagTomat at our website TagTomat.

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