Mushroom Bed

A mushroom bed made with the spent oyster mushroom substrate of Helsieni

Mushroom bed

The mushroom bed is like an edible flowerbed that produces a big and delicious harvest with very little effort!

You can put it around your flowers, under a tree or simply put it in a garden box or even in a plastic tote on your balcony. It is a mulch that  provides you with delicious mushrooms!

You can also use it on the paths of your vegetable garden. It will suppress weeds and as it decomposes it will feed the life in the soil. The oyster mushroom feeds on dead wood or similar high cellulose material and it does not spread in the soil, so it will not invade your garden.

Mushroom bed inspiration

The mushroom path

Mushroom path

keeps the pathways of your vegetable garden clean and prevents weeds to grow.

The mushroom bed

Mushroom raised bed

looks clean and neat – form as you want.

The mushroom totem

Mushroom totem

Use between freshly cut thick logs and get harvests for several years.

How to make a totem

Bags of spent substrate

Bags of the spent substrate

The mushroom bed is spent substrate from our farm. Helsieni cultivates a sporeless variety of oyster mushrooms on a substrate of used coffee grounds and shredded straw. After harvesting 2-3 flushes of mushrooms from it, the substrate becomes quite dry. However, there are still nutrients left in it and it can give a fourth or even fifth harvest as long as it gets a moist place outside.  After this the mycelium has used up all the energy from the substrate and it will become food for soil organisms like worms.

Bags of the spent substrate in the photo.

You can get the spent substrate for your mushroom bed from the Helsieni farm in Kera, Espoo (Finland). The Helsieni substrate is inoculated with sporeless oyster mushroom that is a delicious edible mushroom. You can get there easily by car or by train: the farm is only 200 meters from the Kera train station.

Osterivinokkaita kasvamassa sienipedissä

Mushroom bed

Oyster mushroom spent substrate for your own mushroom bed, path or totem

Pick-up from the Helsieni Farm

Straw pellet

20 kg straw pellets to add to your mushroom bed in order to get bigger harvest

Pick-up from the Helsieni Farm

Helsienen farmi

Seasonal mushroom beds

We offer seasonally spent substrate also for Shiitake and Lion’s Mane mushroom beds

Pick-up from the Helsieni Farm

How to assemble the mushroom bed

The mushroom path


Choose a place

In the garden, flowerbed, vegetable garden, balcony

The best place for the mushroom bed is moist and in the shadow. Natural holes or depressions are great because they usually collect more moisture than their surroundings. You do not need to dig a hole for the mushroom bed. It is best to put it directly on the grass, soil or weeds – easy and simple.

You can use mushroom bed as mulch around trees, bushes or flowerbeds. It prevents weed from growing and produces food for cooking! You can even put the spent substrate on the paths of your garden and walk on it. The increased contact with the soil will help it to suck moisture. Placing the mushroom bed on other mulch may even give you a bigger harvest.

No yard? The mushroom bed also works on a balcony! You can put it in a container that has holes in the bottom to drain any excess water.

Stomping the mushroom bed


Empty the bags

Crumble and stomp

Pick up a convenient amount of spent substrate at the Helsieni farm in Kera. If you have a Growkit you can add its contents as well (after harvesting your mushrooms). Remove any green mould if you see some and put it in the compost or biowaste.

Crumble the spent substrate into pieces – the smaller the better. Put it all in the chosen place and compress well so that the mycelium grows fast together again. You can effectively compress the mushroom bed by stomping and walking on it. The substrate should be at least 10 cm thick after compressing.

You do not need any special equipment for setting up the mushroom bed. If you want you can put it in a raised bed. Just make sure the substrate is in contact with the ground.

Bigger harvest

Mix the spent substrate with some straw pellets or straw! In this way the mycelium gets more food and produces more mushrooms. If mixing is too difficult you can just spread the pellets in layers alternately with the substrate.

Hydrate the pellets

It is simple to water the straw pellets in a wheelbarrow. Put 10 kg of pellets into the wheelbarrow and then fill it with cold water. Allow the pellets to swell for half an hour and use them to your mushroom bed.

The size

The mushroom bed can be easily built inside a pallet collar. One square meter of oyster mushroom bed needs around
☛ 80-100 kg of spent substrate or
☛ 24 kg (3 growing bags) of spent substrate and 20 kg of straw pellets.


Water once

Wait and harvest

Water the compressed mushroom bed thoroughly. Use a lot of water. The mushroom bed does not require further watering in Finland unless the conditions are hot and dry for a longer period. Normally the mycelium gets the moisture it needs from the soil and the rain so you just need to harvest after some weeks when the mushrooms are ready!

If your mushroom bed is in the balcony you may need to water it more often.

Do I need to cover the mushroom bed?

The mushroom bed does not need a cover. If you think a cover would be important in your garden, use breathing material that lets water through like fabric, shredded cardboard or fallen leaves. In particularly dry and warm areas a well perforated plastic may keep the moisture inside.

Why are my mushrooms dark?

The same mycelium grows oyster mushrooms from very light grey to dark brown depending on the outside temperature. Usually the mushrooms grown in the summer are lighter and colder weather makes them darker.

My mushrooms attract flies – what to do?

In warmer temperatures insect populations grow faster and flies can be a problem in summer. You might have to harvest your mushrooms younger to prevent insect larvae eating them. Remove all the rotten, bad or slimy mushrooms and compost them or put them into the biowaste.

Having a diversity of plants and shrubs will create a habitat for predators like spiders and birds around your mushroom bed, and will help control the fly population.

Do you ship spent substrate?

No. Spent substrate is heavy and has a low value. The cost of shipping would be higher than the value of the product. You can pick up spent substrate from our farm in Espoo (Kutojantie 12). If you live in the Tampere area, you can buy spent substrate from our fellow mushroom farm, Satohuone.