TL;DR of the post, generated automatically.

A Blender plant library, with a quick Unreal Engine 5 import test. OP asks for feedback.

• Models: perennials, hedges, trees and meadow packs, sized to measured plant sizes.
• Formats: .blend with packed textures, plus OBJ, FBX, DAE and STL.
• UE5 test: Brunnera imported with Nanite off and on, next to a ruler.