Has anyone tested this yet? In New Leaf if I'm not mistaken I think it was 13 bushes you could put in a row, if you tried to put 14 the 14th one would wilt\not grow. Is it the same in New Horizons? Any TT-ers that have tested this?
I'm wondering this too, it might work like the trees in this game where they don't grow if you bunch them close together, but if you grow them somewhere else and move them by eating something, they can be moved anywhere. You can move bushes like trees so maybe you can have infinite rows?
Sorry, not really a useful post but just suggestion in case the game doesn't let you grow 12+ in a row.
I haven't tested growing them by rows (like as itty bitty baby ones) but I've dug grown shrubs and lined them up together (around 20ish?) and nothing seems to be wrong with them. Though maybe they're like trees, they don't grow properly if are in a row of 5 but can function fine if the not growing tree grows somewhere and be placed back to where it's supposed to be.