Introduction: Mycelial Forms

About: I am a designer, technologist, and educator exploring the imaginative use of emerging technologies. I am most curious about the intricate relationships between technology and our everyday human experience, and…

Mycelium is the vegetative part of a fungus, consisting of a branching thread-like collection of cells called hyphae. Mycelium has a complex network structure, that absorbs and distributes nutrients throughout it's environment. Mycelium is to a mushroom like an apple tree is to an apple. Another way to say this is that the mushroom is the flowering part of mycelium, it spreads spores and allows the organism to spread. This distinction is important, because in this tutorial we will be focused on growing sculptural mycellium forms rather than mushroom cultivation.

This guide explains my own process and experience growing sculptural mycelium forms. There are many approaches to cultivating this material but the process outlined here has been extraordinarily successful for me.

In my own experiments, I played around with incorporating different materials (and colors!) with the mycelium; I had mixed success with this. One approach that did work well was using natural dyes, waxes and resins to create additional structure and visual patterns. In the images above you can see a few of the results.

Step 1: Gather Supplies

  • Inoculated Grain Spawn (mycelium)
  • Coffee Chaff (substrate)
  • 5-gallon coffee pot or other large pot for pasteurizing substrate
  • Nut milk bag for pasteurizing substrate
  • 70% Isopropyl Alcohol for sterilization (alcohol wipes are also helpful)
  • Empty Spray Bottle
  • Plastic Sheet for surface protection
  • Molds to grow mycelium inside of
  • Xacto Knife or Drill for adding a hole in your molds
  • Oven for drying your final forms

For this experiment, the grain spawn was purchased from Aloha Medicinals. The spawn is 100% certified organic, grown on amended white sorghum grain. This particular spawn is Pleurotus ostreatus, also known as oyster mushroom.

*The bag with the larger grain in the photo above is from a different seller from Rochester NY, the following experiments all use the Aloha product, the bag on the bottom left in the photo.

I am using coffee chaff as the base material on which to grow the mycelium. Coffee Chaff is a lightweight and fluffy agricultural byproduct of roasting coffee. Coffee roasters produce a lot of this stuff when they roast coffee beans, and you can typically pick up chaff for free from your local roastery. Wood chips, straw, and other organic materials can be used as the base substrate. In fact, different strains of fungus prefer different substrates. You could do some research about these relationships if you choose something other than the strain I have used here.

Step 2: Prepare Molds

I used silicon ice cube molds and plastic trays for this experiment. You can buy fun molds from amazon or craft stores. Really any shape container will work, the trick is to be able to fully close or seal the mold. Any holes or gaps in the mold could let in contamination and present an opportunity for the mycellium to grow outside of the mold (we don't want this!).

Add a small breathing hold in your mold and fill it a balled up piece of Polyester Fiber Fill. Use a drill or xacto knife to create the breathing hole.

The final sculpture will take on the detail of the mold but it will shrink a bit when it dries - keep this in mind if you are interested in creating something with specific dimensions.

Step 3: Sterilize and Prepare Your Workspace

It is absolutely essential that your workspace remain clean throughout this process. The most common challenge you will encounter in growing mycelium is contamination - resulting in unwelcome mold in your experiment.

Create a sterilization mixture in your spray bottle with 70% isopropyl alcohol in distilled water. You don't need to completely fill the spray bottle, you won't use much of this.

Use plastic sheeting to cover your workspace - I like to tape the plastic so that it wraps under the edges of my table. Spray the plastic surface with your alcohol mixture and let it air dry.

STERILIZE EVERYTHING! Wipe everything with your alcohol mixture. Containers, mixing surfaces, molds, your hands, everything.

Do not let the grain spawn get sterilized by coming into contact with the alcohol. It will kill the mycelium and will not grow. The alcohol solution will evaporate quickly. Be patient.

Step 4: Sanitize Substrate

Before the chaff substrate can be combined with the grain spawn, it needs to be pasteurized (not sterilized).

You will need a large pot of hot water to do this, I had the most luck using a 5-gallon electric coffee pot since it allows me to maintain a consistent temperature. You could also use a large stock pot and a thermometer.

Bring the water to 170° F and maintain this temperature. Fill a mesh nut milk bag with coffee chaff and tie off the top. Add your bag of substrate to the the hot water and allow it to steep for 20 minutes. Carefully remove the bag from the hot water.

Lastly, you will have to press all of the water out of the substrate. We used a custom made wooden hand press to squeeze out the water, a converted cider press would also be a great option. Above all, you want to get as much water as possible out of the coffee chaff, and because it will be very hot you will want some kind of press to help with this.

Step 5: Combine Substrate & Grain Spawn

After pressing the water from the pasteurized chaff, the subtrate will be very compacted and will need to be separated by hand into small fluffy(ish) chunks before being mixed with the spawn. CAREFUL: It should be no surprise that 170F water is HOT.

Once the chaff has been broken up and cooled down, combine 4 parts chaff : 1 part grain spawn mixture. Be very very careful not to contaminate the bag of grain spawn - I like to use a sterilized spoon to scoop from the spawn bag. Dump the grain spawn directly onto the chaff and combine with your hands.

Step 6: Fill and Seal Molds

Fill your sterilized molds with the substrate grain spawn mixture. You want to thoroughly fill the mold but do not pack the mixture in too tightly - it needs some space to breathe and grow. Over time, the space between the material will be filled in by mycelium.

Be sure your breathing hole is filled with poly-fill and that all other gaps are sealed. Mycelium likes air but also likes humidity so don't let it get to dry. Use duct tape to close the mold.

Step 7: Let It Grow

Store your project in a cool, dark and ideally somewhat humid environment.

You will typically see growth within 4-6 days, and your mold will be finished when it looks completely white, which typically takes around 2 weeks.

Watch out for mold or any growth that looks unusual. Mycelium is white and dense looking, any other colored growth, or spotty growth is likely contamination. Mold can be dangerous, and is difficult to get rid of once it starts, if this happens to you it is usually a sign that you should start over and be exceptionally careful about contamination.

Step 8: Bake & Finish

After ~14-16 days, remove the mycelium forms from your mold and allow them to air dry for a few days. You will notice that the forms are moist and delicate, they will harden up as they dry.

Remember that even when your forms dry out, they are still a living material. It is a best practice to bake your forms in the oven for 20-30 minutes at a low temperature (200-220°F).

Step 9: Share Your Thoughts!

I first learned about mycelium through an interest in Permaculture and Micoremediation, and I unexpectedly discovered a beautiful, sculptural material. There are many inspiring examples of existing mycelium works, and an enormous opportunity for future projects - please share your work and ideas, I would love to hear!

I have also posted a Tumblr site with many helpful mycelium resources, books, publications, projects and more! Check it out at A very special thanks to Marina Zurkow and ITP/NYU for supporting my initial inquiry into this material exploration.

Happy making!