we have over 120 peonies in our gardens, so we had to make our own cages. here's what we devised: we buy tomato cages and cut off the feet just ABOVE the lowest horizontal ring. we cut squares of 2"?chicken wire big enough to just fit the circle of the top rung on the tomato cage.
then we bend the corners of the chicken wire over/around the top hoop of the tomato cage. then we push down the tomato cage low enough that the peony's new foliage begins to grow up through the cage. we then lift the cage to its tallest appropriate height after the peonies have max'd their height.
we also use these cages for other perennials that flop- like clematis integrifolia and veronicastrum and cimicifuga and eupatorium. the cages rust and blend in with the ground. hope this is helpful.