I have grown a lot of plants in as much as 50% manure in volume with no ill effects. On top of that I have started adding some NPK fertilizer when transplanting Cruciferae. They seem to love it, but the joke is always that cabbages do well when planted near a cemetery.
I have two x Amarcrinum bulbs I have to pot by Sunday and they'll get their share of manure, no doubt about it.