How to Grow Peonies in Australia

Peonies (Paeonia lactiflora), in the family Paeoniaceae, are long-lived herbaceous perennials grown for their huge, often scented spring flowers. They die down to a fleshy rootstock each autumn and need a properly cold winter to flower. That makes them shine in Tasmania, the tablelands and the hills around Melbourne.

Three mistakes that matter

1. Burying the eyes. Crowns set with their eyes (the pink to red growth buds) more than 5 cm down grow plenty of leaves but few or no flowers. Cover the eyes with 2 to 3 cm of soil, and keep mulch off them.
2. Expecting flowers without winter cold. Peonies need a long cold spell to break dormancy, and the subtropical and tropical zones do not supply it, so plants there rarely flower. Grow them in the cool and alpine zone and the cooler temperate districts.
3. Moving or splitting the clump. Peonies resent disturbance, and a moved or divided plant can take a year or two to flower again. Choose the spot for good, and leave the clump alone for at least five years.

When to plant

Plant bare-root crowns while they are dormant, in autumn and winter: from Anzac Day in the cool and alpine zone, and from May elsewhere. Autumn cold wakes the roots, which grow through winter while the top is bare, ready to shoot in spring.

A crown planted late in winter still settles, provided it goes in before the shoots lengthen. A potted peony in leaf can be planted at other times, at the same depth it sat in its pot.

Site, soil and setup

A clump stays put for decades, so crop rotation does not apply.

Weed status, state by state

Peony is not a declared weed anywhere in Australia, and no state or territory weed list names it.

Container growing

Peonies are deep-rooted and do best in the ground, so a pot is a second choice. If a pot is the only option, use one at least 50 cm wide and 50 cm deep, about 60 L, with drainage holes. Fill it with premium potting mix blended with compost, and add dolomite lime at the rate on the pack. The store's lines are full-sized plants, and no dwarf form is sold.

• Watering. Peonies like a cool, moist soil, so keep the mix moist from the first shoots until the leaves yellow in autumn. In winter, water only when it dries, because the roots rot in mix that stays wet. See watering pots in summer.
• Feeding. Water in liquid potash at the label rate every fortnight from the first buds until flowering ends.
• Position. Full sun on the leaves, with the pot itself shaded to keep the mix cool. Leave it outdoors in winter so the crown gets its chill.

Planting Crowns

Peonies are started from a bare-root crown: a woody rootstock with fleshy roots and a cluster of eyes on top.

Crown planting

Plant crowns soon after they arrive, before the roots dry out. Look for firm roots and plump eyes, and handle the roots gently, because they are fleshy and easily damaged. The five store lines are all Paeonia lactiflora types and are planted the same way.

Planting a bare-root crown

1. Prepare the bed as under Site, soil and setup.
2. Dig a hole twice as wide as the roots, and space crowns 90 cm to 1 m apart.
3. Spread the roots out, with the eyes pointing up.
4. Backfill so the eyes sit 2 to 3 cm below the surface, and never more than 5 cm.
5. Firm the soil gently and water in well to settle it.
6. Label the spot, because nothing shows above ground until spring.

Dividing an old clump

Divide only when an old clump flowers less, and only in early autumn as the leaves die down. Lift it with a fork and hose off the soil. Cut the crown with a sharp knife into pieces, each with three to five eyes and some thick roots. Replant at the depth above. Divisions usually take two years or more to flower well; see dividing perennials for the method.

Care by growth stage

Peonies feed and root while they look dormant, so autumn and winter matter as much as spring. Steady moisture while buds form decides how well they open.

Put a peony ring or three stakes and soft ties in place as the shoots appear, before the plant fills out. In the first spring, pinch off any buds so the plant puts its strength into roots. Feed with restraint, because too much fertiliser, especially nitrogen, can cut flowering.

Disbudding and Deadheading

Disbudding sends a stem's strength into one large flower, and deadheading keeps the clump tidy and its leaves at work.

• For big blooms, snap off the small side buds beside each main bud as soon as they can be gripped.
• For a longer show in the garden, leave the side buds to open after the main flower.
• Cut each spent flower back to the top leaves, leaving the leafy stem standing.
• Let the leaves yellow and die down naturally in autumn.
• In late autumn, cut all stems off at ground level.
• Bin the old stems and leaves rather than composting them, so disease does not carry over.

Companion planting

Pair peonies with plants that like the same sun and drainage but stay clear of the crown.

Grows well with

• Bearded iris, which shares the sun, drainage and lime and contrasts upright leaves with mounded ones.
• Catmint, a soft, low edging that hides the bare base of the stems.
• Ornamental alliums, which flower with the peonies and take little room.

Keep apart

• Trees and large shrubs, whose roots and shade cut flowering.
• Lawn, whose grass competes for water right up to the crown.
• Vigorous, spreading perennials that invade the clump's square metre.

Harvesting Blooms

Cut when the bud shows its full colour and gives slightly when pressed, like a marshmallow, or at the latest as the outer petals unfold.

• Cut sparingly in the second year, while the roots build.
• Cut in the cool of early morning, with clean secateurs.
• Leave most of the leaves on the plant to feed next year's flowers.
• Recut each stem about 1 cm shorter under water, then stand it straight in a vase.

Blooms usually last up to a week in a vase. Flower growers hold cut buds in cool rooms for up to two weeks, so stand the vase somewhere cool.

Common problems

Leaves but no flowers. Young plants often skip flowering for a year or two while the roots grow; otherwise see Three mistakes that matter.

Fewer flowers each year. Shade from growing trees or crowding in an old clump; move the plant to sun, or divide it in early autumn.

Buds that brown and fail to open. Dry soil in spring starves the buds; keep watering through bud stage, and check for the mould and insects under Pests and diseases.

Stems flopping after rain. Double flowers fill with water and bend the stems over; set rings or stakes as shoots appear.

Ants on the buds. They feed on sugary sap from the buds and do no harm, so leave them be.

Scorched, faded petals. Hot afternoon sun burns open flowers; give afternoon shade in hot districts.

Pests and diseases

Peonies in a suitable site are seldom troubled, and most problems start with wet, crowded or shaded plants.

Grey mould (Botrytis cinerea). Young stems wilt and collapse, and buds turn brown and grow a grey fuzz, mostly in cool, wet springs. Cut out affected parts at once and bin them.

Garden snail (Cornu aspersum). Snails and slugs target the soft young shoots of herbaceous plants, so the reddish shoots are at risk in late winter. No record names peony as a particular host. Hand-pick on damp evenings and use an iron-based bait if needed. Read more

Thrips (Thysanoptera). Tiny insects that feed in buds and flowers, which then open deformed and discoloured, or not at all. Flower thrips are common across southern Australia, though no record names the species found on peonies here. Spray insecticidal soap late in the day, never on open flowers where bees feed. Read more

Powdery mildew (Erysiphe species). A white powdery coating spreads over the leaves later in the season, worst in shade and still air, and seldom harms the plant. Remove the worst leaves or spray 1 part full-cream milk to 10 parts water, and bin all foliage at the autumn cut. Read more

Prevention first

• Plant in full sun with space around each plant for air to move.
• Water the soil, not the leaves and buds.
• Cut back and bin the stems in late autumn, as under Disbudding and Deadheading.
• Clear litter where snails shelter before the shoots appear.

Tips

1. Treat a peony as a lifetime plant: a clump in the right spot can flower for 20 years or more without lifting.
2. Peonies are toxic to dogs, cats and horses and are not a food plant, so plant them away from pets that chew.
3. Tree peonies, with woody stems that stay above ground all winter, are a different plant; the store's lines are herbaceous and die to the ground.

Due to quarantine restrictions and our shipping policy, we cannot send peony plants to Western Australia or Tasmania.