I got some STLs for hedges from https://www.wargaming3d.com/product/hedgerow-bocage-terrain-for-6mm-10mm/
They're presented as being for 6mm - 10mm gaming scales, and they're certainly best for those, but they're also quite usable for 15mm. In any larger scale though I think they'd just look like a herbaceous border planting.
These sorts of things are quite easy to make with some ice-block sticks and clump foliage, but the advantage (to me) of 3d printing is that I can just click-and-forget, come back the next morning and pull a bunch of hedgerows off the printer. Of course they need painting, so they're not entirely labour free, but painting them takes very little time or effort. Also, they're pretty well indestructible unless you jump up and down on them with hob-nailed boots. I can just toss them into a box without fear that they're going to lose any foliage.
Here they are alongside some 1/300 scale (5-6mm) Heroics & Ros Napoleonics, Spaniards in point of fact.
In this scale they're easily bocage-size. If you wanted smaller hedgerows, they're easily rescaled down in the slicer, and they'd print a lot faster too.
In 10mm (1/150 - 1/144 scale) they're also large enough to represent bocage.
Unfortunately I don't have any 10mm infantry. I printed this 1/150 Bishop as a test of one of Mr. Bergman's 1/200 scale models, just to see how it would look on the table, but I don't actually play in that scale. I would though, if I were starting out again from scratch.
In 15mm they're still head-high hedges, suitable for planting around pastures and what-not.
It would be a simple matter to rescale them a bit to create 15mm bocage, though unless you have a big printer the larger STLs would probably not fit on the print bed.