Based on our own experience of importing from the Northern Hemisphere we have found that it is perfectly satisfactory to plant peonies from shipment straight into the ground in early summer without any further treatment. However, a reasonable percentage (say up to 50%) may not come up or may come up very small in that growing season but will survive perfectly well to come up in the following spring.

Alternatively, the plants can be put in a chiller at, say, 2 degrees centigrade (not frozen!) for 3-4 weeks and planted thereafter. A large percentage of these will come up and grow in that summer/autumn period. Given the chilled treatment for one month, the only varieties we found did not come until the following spring were some early hybrids.

Given that more varieties sprouted after being put into the chiller, one might assume this is a better technique than planting out straight into the ground. However, in the chiller, the plants do not have an opportunity to grow feeder roots into the surrounding soil before they sprout once planted. There they do not grow very much, whereas the peonies planted straight into the ground are able to grow their fine feeder roots before they decide to sprout. My impression is, because of the very short subsequent growing season with poorly established feeder roots, not much is gained by the chiller treatment. In other words, by the end of the second growing season, the plants that were planted straight into the ground were just as big as those that had had another short season due to the chiller treatment.

While we cannot give an absolute guarantee of any plant variety coming up, we have never observed any plant losses, even if they don't come up until the following spring. Peonies, as a general rule, are very hardy, durable plants.