Flower Wall

The version already sitting in the world, in forest patches and around Enchanted Sword Shrines, does not stop anything spawning. Break it and put the same wall back yourself and it does. If you are turning a shrine into a build, clear every naturally placed wall and replace it rather than leaving the originals in the background.

Spray it and it becomes the corrupt, crimson or hallowed grass wall to match the solution. Green Solution will not bring the flowers back; you get plain grass wall instead. Replacements are cheap from the Dryad, so it is an annoyance rather than a disaster.