I read that rhubarb leaves are toxic. Can they be put on the garden or compost to rot without problems?
Hey JRH, people have long been concerned about adding rhubarb leaves to their compost piles. Their logic being that if the leaves are poisonous to humans, then they must be bad for compost as well.
And it is true that rhubarb leaves contain a high concentration of oxalic acid which is toxic to humans causing kidney failure.
HOWEVER
What actually occurs when rhubarb is added to a compost pile is that the oxalic acid is decomposed and pH neutralised rather quickly.
Experience has also shown that the level of acid does not inhibit the microbial action of composting.
Compost piles which contained many rhubarb leaves have decomposed very nicely and the compost has behaved like ordinary compost with no inhibition of plant growth being noticed from the subsequent application of the compost to garden beds.