In autumn, the condition of peonies varies significantly: some bushes have both stems and leaves drying out, while others have buds swelling on bare branches, ready to develop into new shoots and flowers in the spring. This is why there is no single "pruning day"—care depends directly on the plant group and how it weathered the summer. Below are practical rules provided by US university experts and gardening publications that help the bush survive until spring.
When to Cut Back Herbaceous Peony Stems
As long as herbaceous peony leaves are green and healthy, the plant is actively accumulating nutrients in its roots, preparing them for the next season. Cutting back stems is only appropriate once the foliage turns brown and dry—this typically happens after a hard frost, as experts from Iowa State University explain. In temperate zones, this usually happens in the second half of October; in northern regions, by the end of September; and in the south, in November. If the bush is diseased, affected foliage should be removed immediately without waiting for cold weather.
Cleaning Debris and Disinfecting Tools
It is important to remove fallen leaves and cut stems from the flower bed: fungal pathogens can overwinter on them, so these remnants should not be placed in home compost, warns specialists from the University of Minnesota. If the leaves showed spots or powdery mildew, the pruning shears' blades must be cleaned and disinfected before moving to the next bush to avoid spreading the infection.
Mulching Young Bushes
Well-established herbaceous peonies and Itoh hybrids usually overwinter without cover; the main requirement is that water does not stagnate at the roots. An exception is the first winter after planting: the bush can be mulched with bark once the top layer of soil has frozen. Mulch reduces the risk of the soil heaving the roots to the surface during freeze-thaw cycles. In early spring, the bark should be pulled away from the crown, as recommended by the American Peony Society.
Protecting Tree Peonies and Itoh Hybrids
A tree peony growing in an exposed location can be protected from strong winds with a mesh screen. It should be placed some distance from the branches on the windward side, advise experts from the University of Maine. Itoh hybrids, which combine traits of herbaceous and tree forms, generally behave like established herbaceous peonies and, provided there is adequate soil moisture, do not require additional cover.
Autumn Watering and Fertilizing
Adult, established bushes generally get enough moisture from autumn rains. If the soil near a recently planted peony is dry and not yet frozen, it should be watered—this helps the plant establish before winter, explain specialists from the University of Nebraska-Lincoln. Scheduled autumn fertilization is not necessary, notes the University of Connecticut: it is best to avoid extra fertilizer to prevent stimulating late growth and provoking rot under the mulch.
