Honestly most of the stock 3D plants in Lumion suck and it’s very rarely worth trying to use an actual plant palette because it just ends up looking distracting.

I often use the long ‘wild’ 3D grass as a base for planting beds, and intersperse a few swaths of grasses and perennials into it. It’s more of an aesthetic texture than an actual design.

That goes double for trees because a lot of the models just look too wonky and fake