No issues with the colours, and I still love your clusters as much. Those beautiful flowers you have, however, make the scene look more artificial (as in garden), imho, especially given how they stick to the grid. The flat, white ones are those that work best imho. They get a bonus for a second variant (be it blue, yellow or orange), but again, mixing all the colours together is something you make in a garden, but that I'd not expect from wild life. As a level designer, I'd likely as you for logs instead of flowers-to-line-up, but I might be happy to pick one of those higher-flowers and use it as a way to make specific locations more memorable.
some experiments:

- variation on how much "higher grass" you have around a tree will reduce how "similar" tree look.
- allowing half-tile alignment on flowers could make them look more organically-placed.
- for some flowers, a 2 or 3-tiles patch might work better than individual items.
Any ideas for NPCs or monsters ?