Every landscape I do ends up with at least one patch of green that looks like swamp sludge. I've been blaming cheap paint, but I was mixing ultramarine with yellow and just adding more yellow when it got ugly, like I could shovel my way out of it. Tonight I actually tried mixing in a touch of the burnt sienna I use for everything else and it just... worked. The green sits better and reads as distance instead of mossy soup.

Twenty years of painting and I still do dumb things out of habit until someone says the obvious thing out loud. Anyway, try a pinch of your brown before you buy another tube of green. Wish someone had told me that in 2019.