Golden Gills

What luck to stumble upon this cluster of noble Gymnopilus ventricosus in the middle of May on a bright and sunny day! Spring this year (2020) consisted of several cycles of intense rain followed by intense heat uncharacteristic for the Bay Area. I had seen a few out-of-season fungal flushes earlier in April, including a stellar find of Shaggy Parasols (Chlorophyllum olivieri) bigger than my hand and right on the cusp of being too mature.

These Jumbo Gyms, however, were nicely mummifying for me right where they stood. I spotted them on the way up a day-long hike and vowed to get a closer look on the way back. I wasn’t expecting to forage anything that day, but I tied up my sarong scarf sashiki-style and made a large purse for the treasure trove of mushrooms I cut off of the trunk and picked up all around the base of the tree.

All told, I clocked in a whopping 440g of dried specimens that barely packed into 5 quart jars! Plenty for a sweater and then some.


Alissa Allen’s Gymnopilus ventricosus recipe calls for 2:1 mushroom-to-fiber by weight, with an acidic pH of 4ish (a solid glug of vinegar) to brighten the resulting buttery yellow. Though I am prone to optimistically trying to stretch dye specimens and using too much fiber, I was adamant that the next garment I wanted to knit for myself was a cardigan darnit, and so I insisted on dyeing up 600g of superwash merino wool.

Superwash wool does tend to amplify the effects of natural dyeing, giving more saturated and vivid colors with less of the dye goods, likely because it has been chemically stripped of some of the wool fiber’s scale and thus color can bind more readily to the fiber. In any event, I forged ahead and promised myself this would be the last time I would risk an underdye for my ego. Natural dyeing feels like such magic sometimes that it’s easy for me to forget it’s really and truly a science.


  • 600g superwash merino wool yarn (Knit Picks Swish Bare), mordanted with alum
  • 440g dried Gymnopilus ventricosus
  • large stockpot (just like in chemistry class, your dye utensils should not double as food utensils)
  • Synthrapol or a few drops of dish soap
  • chopstick or tongs (not used for food)
  • household white vinegar
  • pH strips
  • enough water to cover the specimen (to control for variables, it’s advised to use distilled and/or filtered water. I used tap.)
  • optional: instant read thermometer or infrared thermometer


Rustgills indeed. I’ve concluded that it’s not the spores that contain any dye pigment, but truly the flesh.
  1. Fill the stockpot with enough water to cover the dye goods and add the dried Gymnopilus ventricosus mushrooms.
  2. Bring to a simmer and hold for an hour.
  3. While the dye bath simmers, soak the 600g of fiber in a bowl or pot to pre-wet.
  4. Add white vinegar to the dye bath, measuring the pH one glug at a time, until the pH is lowered to ~5.
  5. Add the fiber to the dye bath, keeping the mushrooms in for the variegated effect of “contact dyeing”.
  6. Turn off the heat and let the fiber sit in the bath with the mushroosm overnight.
  7. The next morning, bring the whole bath back to a simmer and hold for an hour.
  8. Let the bath cool, then remove the fiber and squeeze (don’t wring!) out the water.
  9. Rinse the hanks of yarn 3 times to remove all the rusty spores from the mushrooms.
  10. Hang to dry out of sunlight.

I often don’t rinse natural dye yarns right away, or if I do, I don’t use soap at the end. Some dyes do require the oxidation process in order to bind properly to the fiber. This is clearly not the case with Gymnopilus. The yarn came out of the pot a really dingy, greyed out yellow that made me feel crestfallen. I worried I had rushed the process too much by shoving the yarn in with the mushrooms bits before they had been fully processed to release all their dye potential. Normally I love the uneven, “kettle-dyed” handmade look of contact-dyeing, where leaving the dye material in the pot will cause more color to bind to the yarn touching the dye material. I was all in a panic that I had ruined the whole batch.


I got my butter yellow and more! These mushrooms felt like the gift that kept on giving. I now know to trust my instincts; these big ole mushrooms have a lot to give in them if you’re just patient enough. 1 hour was not enough time to maximize their potential at all!


I would absolutely dye with these mushrooms again in a heartbeat, and you’ll bet that I’ll venture out to that trail again come winter when the rains hit. I absolutely adore the cardigan I have from the yarn, and I somehow have another 100g leftover that hasn’t told me what its destiny is just yet.

Pattern: Straight and Arrow Cardigan by Stacey Gerbman


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