Oh that's gorgeous - good luck finding something. I could see how that would do amazingly as curtains.

ETA: Actually, wait, I managed to dig up a link to the image (haha, fuck you, blocking right-click, vendors): and did a Google Reverse Image Search on that thing. There are some Spoonflower fabric results that are similar, plus some Redbubble results.

There's Winflo Curtains, but they're in Tasmania.

"Dark Botanical" or "Dark Wildflower" seems to be a common search term.