"Hello, I love your blog, I have a question for you. I know transplanting in the spring is not best, but I had no choice. Now I have over 100 peonies to replant. Some are very young with only 3-5 eyes. I know to plant those whole. But what about the ones that have large root masses, but only 3 eyes showing. Is it problematic to replant those whole? I remember reading that once dug up peonies prefer to be split to grow properly. Should I trim some root off those. For a visual imagine 8 big juice carrot sized roots, with only three tiny eyes. Also, do you have any tips for soil amending when planting? I have access to leaf mulch, wood chips, well aged horse manure, worm compost and regular compost. Thank you for any and all advice you can offer"
Thank you for such a nice compliment! You are correct in stating that spring is not the ideal season to transplant peonies. Fall is the best season for moving and dividing peonies. However spring is much better than summer, especially if the peonies have not yet sprouted (which is what it sounds like you are describing when you mention that your peonies have eyes - instead of foliage growth). You may notice some reduction in blooms this year, but provided these peonies are replanted in a good location with plenty of sun and nice soil, they should recover nicely. If any of your peonies had enough stems last year to divide (at least 7-8 stems), then you can go ahead and divide those peonies. However if your peonies didn't have very many stems last year and only have 3 eyes with large roots, I would not divide those peonies. Also it isn't necessary to remove any of the storage roots before planting unless you feel need to remove them for some other reason (ex. unwieldy for planting, unmanageable for transporting, diseased, etc.)
As far as soil amendments, I would recommend the leaf mulch and compost and mixing it well into the soil. The horse manure could also be used, but it definitely shouldn't be applied directly to the roots or crown of the plant. The wood chips could be used as a mulch/top dressing only to prevent weed growth. However it is not recommended to mix these into the planting hole, as they can inhibit the peony root's access to nitrogen.