Peony

Light and exposure

The peony loves sun. Give it a wide open spot, in full sun or at most light partial shade, with at least five to six hours of direct light a day. The more sun it gets, the more generous the flowering and the sturdier the stems.

Avoid the foot of large trees and the dark corners of the garden. In shade it stalls, grows leggy and refuses to flower. An airy position is also a good defence against the diseases of a damp spring, common wherever the growing season starts mild and wet.

Watering

Once established, the peony asks for little and copes well with dry spells thanks to its fleshy crown. For the first two years, help it root with regular watering during prolonged drought, especially in spring when it is growing and forming its buds.

Avoid excess water and soils that stay waterlogged in winter, the crown rots quickly in cold damp. Water at the base, never on the foliage, so you do not encourage botrytis in overcast, rainy weather.

Soil and repotting

The peony wants a rich, deep, well drained soil. It sends its fleshy roots far down into the earth, so take care with the preparation: dig deep and work in mature compost or well rotted manure, keeping it away from direct contact with the eyes.

It tolerates chalky and clay soils as long as they do not stay soaked. On heavy clay soil, improve drainage with compost and a little coarse sand, or raise the planting area slightly.

Temperature and humidity

This is a genuinely hardy plant, built for sharp winters. It takes down to -30 °C and needs no winter protection once established. Better still, it needs the cold of winter to flower well: several weeks of dormancy below 4 to 7 °C trigger bud formation.

Late frosts at the end of winter can sometimes scorch a young shoot or damage an advanced bud, with no lasting consequence. The plant starts again from its crown without flinching. Overwintering raises no question at all in a temperate or cold climate; it is under a winter that is too mild, for want of cold, that flowering falls away.

Pruning and upkeep

Care depends on the type of peony, and this is a point to get clear. The herbaceous peony disappears completely in winter: cut all the foliage back to ground level in autumn, once it has yellowed, and remove it from the garden to limit disease. It will start again from its crown in spring.

The tree peony, on the other hand, has a woody framework that stays in place all year. Never cut it back to the ground: simply remove dead wood and damaged branches in spring. During the season, cut spent flowers just above a good leaf on both types.

Pests and diseases

The main enemy is peony botrytis (Botrytis paeoniae), favoured by mild, damp springs. You spot it by young shoots that blacken and wilt abruptly at the base, and by buds that brown without opening. Cut off and clear away any affected part promptly, do not leave it at the base.

To prevent it, work on airflow: do not crowd the plants, open up the centre of the clump, water at the base and cut the herbaceous foliage back cleanly in autumn. A mulch that is too thick against the crown keeps in moisture and the fungus, so stay light near the eyes.

Propagation

Division is the go to method for the herbaceous peony, but it is done in autumn, once the heat has dropped and the foliage begins to yellow, and no more often than necessary. Dig up the crown, let it dry off for a few hours, then cut it with a knife into pieces each bearing three to five eyes. Replant at once, eyes 2 to 3 cm below the surface.

Be aware that the peony hates being disturbed. After a division or a transplant it may sulk for a year or two before flowering again, the time it needs to rebuild its roots. That is normal, do not lose patience and above all do not move it again. Growing from seed is possible but calls for a lot of patience, several years before the first flower.

Month-by-month care calendar

Green Hub tips

• Never plant the herbaceous peony too deep: the red eyes must stay 2 to 3 cm below the surface, otherwise you will get leaves but no flowers, sometimes for years.
• Choose its spot once and for all: it hates being moved and may sulk for a year or two after planting or division before flowering again.
• Ants on the buds are not a problem, they come for the nectar. Let them be, no treatment is needed.
• Tell your peonies apart: the herbaceous type is cut back to the ground in autumn, the tree peony keeps its woody framework which must never be cut down.
• Put the stakes in early, as soon as the stems reach about twenty centimetres, before the large double flowers flop over in the first heavy rain.