Peony Mary Eddy Jones
Peonies are tough plants that can survive some pretty adverse conditions but a little care changes surviving to thriving. Fall care is important.
Autumn is the best time to plant bare root peonies and the best time to move them or divide them. As the soil cools down peonies make their new roots; they benefit from six weeks of root development in cooling soil before the ground freezes.
Established herbaceous and intersectional (ITOH) peonies should be cut to the ground. Some people leave a little bit of the stem but cutting them close to the ground reduces the chance of fungus spores and pathogens over wintering. Tree peonies should have the leaves removed and woody stems left intact.
The cut foliage of all peonies should be placed in a separate container for disposal. It should not be placed on the ground or added to garden compost to avoid spreading spores. Remove and discard all debris from around crown of peony; this includes leaves and old mulch. Debris could provide a place for fungus to thrive.
Once the peony stems are cut the tools and pruners should be disinfected between each peony. One part bleach to nine parts water is effective.
Fall is a good time to place a layer of compost around the crown (never on top). Loosen the soil around the crown when applying compost. This is also a good time to fertilize peonies. Fertilizer should be spread around the crown, never on top to avoid fertilizer burn. A slow release low nitrogen bulb fertilizer is best, about 4 tablespoons per plant. NB it is always wise to test soil before amending it.
Make sure your peonies stay hydrated right up to freeze, about an inch of water per week. Water around the base if Mother Nature is not helping.
Peonies especially newly planted ones can be susceptible to frost heave in our typical Northumberland winters. You can add a layer of mulch in late fall; it would have to be removed in spring as soon as new growth appears. Another option is to place evergreen boughs over peonies after freeze up. The evergreen boughs trap snow and help reduce freeze thaw cycles.
Good fall care results in healthy spring peonies.
authored by Northumberland Master Gardener Joy Cullen