I grow Eremurus but have only ever planted them in fall. The first time was roots from Dutch Gardens that had all the spidery roots trimmed off and none showed the following year. The next couple of times were Spring Valley hybrids from Brent and Becky's that grew and flowered well and returned perennially. They were described as being more vigorous and reliable than Dutch imports.
Several years ago I tried some ornamental Curcuma, and I do recall them being very slow to emerge. I believe warmer days of summer will trigger them to sprout, similar to cannas and elephant ears in that regard.
