I was recently in California (feb 2020) and gathered about 300g of blue gum eucalyptus leaves for my first eucalyptus dyeing experience. I did equal weight fiber to dye, a small 15g test batch and followed Babs Behan’s recipe: I broke up the leaves into small bits and simmered them with my Denver tap water for 3 hours, then let them cool in the pot overnight. The next day I strained the leaves, then divided the bath into two small pots (this came to about 4-5 cups of water in each) I added 1 TBS of homemade iron mordant solution to one pot, and cold immersed a 7g strip of (scoured, unmordanted repurposed cotton) into the bath. The grey sample above is the iron + eucalyptus cotton cold immersion overnight in the dye bath. I took half of this sample and heated the iron + euc. Bath for 30 minutes, let that sit overnight, and it was barely distinguishable to the shorter, cold immersion bath. The warm khaki I got is the eucalyptus by itself, I heated that bath for 30 minutes, then let cool overnight with fabric immersed. Washed, rinsed, dried.