An iris friend told me to cover the rhizomes with regular dirt to stop the crickets. If you can't find what has been advised try planting the rhizomes just under the soil. They will adjust themselves as they grow or you can pull the dirt back in the spring if you feel the need.
<<full of holes >>
They were killing some seedlings I had potted in 3" pots. They got two of only four seedlings from a favorite cross. The rhizomes are just to small to withstand crickets. In this case I moved the pots/trays off the ground and onto a garden bench.
KY Zone 6