Which bush exactly? There are a few choices! I posted the step shapes for fire in another comment. The third row is fire upright. You can't get that bush on the leftmost side of the map from the go back to trophy room nook below. You can see no upright fire shape fits.
If you are talking about the bush just upper left of the center star with two blocks sitting on it, you can't pass it. But you have already solved the hardest 2 parts of the puzzle if you have reached that nook before the tower of five blocks comes crashing down behind you. The solution is right there, just not through that bush.
Key fire was probably my favorite trophy overall for where I was in the learning process. It also took me a while, although I got hung up on two different steps.
