We love using the log inoculation method for growing mushrooms. It is a technique to reliably grow mushrooms that mimics nature & has been used successfully for hundreds of years. Oftentimes, folks are cutting down tree limbs because the limb is threatening their house or a power line. Sometimes farmers need to open the canopy up to let more light in to grow their crops. At times, some tree species are introduced from other areas that can take over entire ecosystems & grow in an unwanted monoculture, as is the case with the Octopus Tree (aka: Umbrella Tree [H. actinophyllum / S. actinophylla]). In our tropical area, folks are regularly cutting this tree down because – without proper management – it can cover entire hillsides in short order leaving very little room for endemic species to thrive.

Umbrella Octopus Tree

Octopus Tree taking over an entire hillside
image by Forest & Kim Starr | PlantPono.org

In each of these cases, instead of sending the wood to the landfill, we can inoculate it with mushroom mycelium to grow food for our community. Octopus Tree has been a success story in tropical mushroom cultivation on logs. The wood myceliates quickly & produces large flushes of mushrooms after only 6 months of incubation time.

Oysters on Umbrella Tree bolt

Our most recent flush of Oyster Mushrooms on Octopus Tree logs in the food forest.
Inoculated in 2021, still flushing mushrooms in 2023!

With this success, we decided to try a stump inoculation. Stump inoculation is when, after the tree has been cut down to its stump, holes are drilled in it to introduce gourmet mushroom mycelium. The living mycelium will eat the dying wood & use the nutrients in the wood to grow tasty mushrooms. Generally, since there is so much woody material in the underground root system it takes quite a while for these stumps to completely myceliate & then start producing mushrooms. But when they do, oh WOW do they ever…

Oyster Mushrooms on stump

Stumps inoculated with mushroom mycelium have been known to produce mushrooms for decades!

Knowing that Octopus Tree is a very “vigorous” species & that it could possibly resist the mushroom mycelium’s vigor, we decided to drill A WHOLE BUNCH of holes in the stump & introduce A WHOLE LOT of mushroom mycelium in the holes so that the fungi would eat the wood before the tree tried to pounce back to life…

inoculated Octopus Tree stump

Octopus Tree with a TON of inoculation points all over & around it.

Well, like you, we are also very busy doing lots of things in life: growing mushrooms, waking up at all hours to change diapers, hiking & looking for mushrooms, washing diapers, creating new mushroom educational content, wiping baby bums, prepping & cooking mushrooms, etc.

As a result, we neglected to check up on this stump inoculation project. Plus, we knew it was a very big stump, so it would likely take quite a while to myceliate before it produced mushrooms. “Let’s just check up on it again in a couple of years”, we said to each other.

Well, that’s what we did… and here is what we encountered a couple of years later..

Octopus Tree GROWING BACK!


The tree not only survived, it is THRIVING, which is great for the tree, of course.
And we learned a lesson. We hypothesize that with a tropical tree species that is this vigorous that the best practice would most likely be to:

  • Cut the tree down to the stump,
  • introduce mushroom mycelium in a lot of inoculation points,
  • and then REGULARLY RETURN to the stump to prune back any new growth in order to aid the mushroom mycelium in eating the stump.

While we are not 100% sure that this pruning hypothesis will work with Octopus Tree, the next time we inoculate the stump of such a vigorous tree species we will be trying a more hands-on approach!

Do you have any ideas on how to grow mushrooms on the stumps of vigorous tropical trees like this one. If so, then please contact us.

And if you would like to learn how to grow mushrooms in the tropics the fast-track way by learning what works as well as what NOT to do – because we likely already tried that – then please check out our upcoming mushroom education offerings where we will show you the ways that have worked the best for us. 

One of the most common questions we get from participants of our mushroom cultivation workshops is: “Can I grow mushrooms on Guinea grass (Megathyrsus maximus)?” It is a great question given the abundance of this grass species. As we hadn’t yet tried it ourselves when previously asked, our response to participants was: “Possibly. Try it out. If you succeed then let us know so we can tell others!” After a couple of years of getting this question & giving folks the same response, we decided to try it ourselves…

Guinea Grass (Megathyrsus maximus) by Beth Addison-smith | CC0 public domain | iNaturalist

Guinea Grass (Megathyrsus maximus) by Beth Addison-smith | CC0 public domain | iNaturalist

Guinea grass, originally native to Africa, has been widely introduced throughout the tropics as forage & fodder for domesticated animals. Due to its tendency to displace native plants, Guinea grass is considered an invasive weed in many locations around the world.

Loss of native plant biodiversity is not the only concern related to invasive Guinea grass. According to HawaiiWildfire.org, Guinea grass is a fire-prone species. In a scientific paper published in Applied Vegetation Science, the authors warned that “once forests are converted to grassland there is a significant increase in fire intensity, which likely provides the positive feedback to continued grassland dominance in the absence of active fire management” (Ellsworth et al. 2014).

Given the invasive nature of Guinea grass here in the tropics along with the heightened curiosity of our mushroom workshop participants about this free, abundant, local resource, we decided to look more closely at using this grass as a substrate (food) for growing gourmet mushrooms on in order to help cut back on the spread of this invasive species. We were excited to uncover a recently-published scientific paper proving that oyster mushrooms can in fact be grown on Guinea grass (Somashekhar et al. 2020). This gave us an extra confidence boost & spurred us to action!

After reading the paper, we grabbed our sickles, cut down some Guinea grass that was growing in our back yard, laid it out to sun-dry, pasteurized it & then inoculated it with pink oyster mushroom spawn (mycelium). We decided to use re-usable glass jars as the container for incubating the mycelium as well as for fruiting the mushrooms from. After just over 2 weeks, we had pink oyster mushrooms growing from the Guinea grass out of our glass jar! Woo-hoo!

mushrooms on Guinea Grass

Mushrooms growing on Guinea grass by Summer, Dave, & Chase | Tropical Fungi Academy

Now, what do you do with the bare spot in the back yard where the Guinea grass was growing? How do we make sure that native plants will thrive there now? After cutting Guinea grass for use as a mushroom substrate or fodder, it is recommended to plant a diversity of native plant species in its place – as opposed to just planting a single native plant species – in order to achieve a higher success rate at having native plant species become re-established in the restoration habitat (Ammondt et al. 2012 & 2013).

We are so stoked that this worked & hope you will try this method too. We will definitely continue to be open to recommendations on which invasive species to grow mushrooms on. So if you would like us to try growing mushrooms on another species, please let us know which species & we’ll give it a shot!

If you want to learn more about growing gourmet & medicinal mushrooms on invasive species & other abundant substrates, be sure to check out our upcoming educational offerings by clicking on this link.

Thank you all for attending our last identification & low-tech mushroom cultivation workshop last month! We were so stoked that participants found over a dozen different species of fungi at the workshop even after such a prolonged dry spell!

Culinary & medicinal fungi found included: Snow Fungi, Paddy Straws, Cloud Ear, & Fan-Shaped Jelly Fungus.

Fan-Shaped Jelly Fungus

Fan-Shaped Jelly Fungus

Medicinal fungi found included: Bloody Polypores & Northern Cinnabar Polypores.

Bloody Polypore on wood

Bloody Polypore

Poisonous fungi found included Flowerpot Parasols & Onion Earthballs.

Onion Earthabll

Onion Earthball

Curious & beautiful fungi found included: Tinypores, Bird’s Nest Fungi, various Stinkhorns including Sea Anemone Stinkhorns, Split Gills, & Spring Polypores.Stinkhorn Egg

Stinkhorn Egg

An update on our low-tech project we created together: several of the spent coffee grounds & used cardboard oyster spawn jars have fully myceliated & have just now been set up for fruiting mushrooms!!!

jars myceliated

oyster myceliated spent coffee ground jars

Thanks to Chef Nicot for slicing & dicing that mountain of cloud ear fungus!

cloud ear fungus meal

Cloud Ear Fungus meal by Chef Nicot

See you all at our next workshops!