How do I grow peonies?
Herbaceous peonies only grow in cool climates with cold winters such as Tasmania, Victoria and mountain districts – they need cold to help trigger the development of the flower bud. Tree peonies also prefer cold climates but will also grow in cool temperate areas.
Position herbaceous and tree peonies in full sun and shelter from strong winds. In climates with hot summers, a lightly shaded spot is preferable.
Plant in deep, moist and well-drained soil enriched with well-rotted compost and manure. A neutral soil pH is desired by herbaceous peonies but tree peonies prefer a more alkaline soil, so add dolomite lime and fork in well before planting.
Keep soil moist, but never wet. In summer, water to keep soil cool and ensure it doesn’t dry out. Once established (1–2 years), tree peonies are quite drought tolerant, but benefit from regular watering throughout the growing and flowering season.
In late winter, feed herbaceous peonies with a well-balanced fertiliser and remove surrounding weeds. Apply fertiliser again in summer after peonies have finished flowering and you have deadheaded. For tree peonies, feed in winter and late spring with a fertiliser low in nitrogen but high in phosphorus and potassium. This will help encourage strong root growth and flowering.
While it is possible to transplant peonies, generally speaking they don’t like to be disturbed, so choose your location carefully. Prepare the soil by incorporating well-rotted compost and manure (and dolomite lime, if needed) a week prior to planting.
• Herbaceous peonies are sold as bare root rhizomes with a few buds or ‘eyes’ and are best planted in autumn. Dig a shallow hole no more than 5cm deep and firm the base of the hole. Position rhizomes with buds facing upward, backfill and lightly firm soil, then water thoroughly. Plant at least 60cm apart – they like a little space between plants.
• Tree peonies are sold in pots. Dig a hole twice the width of the pot and a little deeper. Remove plant from pot, gently tease out roots and position in hole. Backfill and water thoroughly.
• As herbaceous peonies grow, use a three-legged metal wire frame to help support the stems. Look for them at your local garden centre. Don’t be surprised if there are few or no flowers in the first year – the plant is still developing and will flower once it grows into a healthy bush. In late autumn, allow foliage to naturally die down before pruning. When the bush flowers, cut long stems for indoor display or deadhead regularly as flowers fade to encourage more blooms.
• Tree peonies only need pruning to remove dead or broken branches – they should only be pruned as the growing season starts. Apply a generous dose of dolomite lime to the soil every three years and water in well.
Herbaceous vs tree peony
Herbaceous peonies, also known as Chinese peonies (Paeonia lactiflora), are the most commonly grown. They grow from rhizomes, which form a bush about 1m high and flower from late spring into summer, before dying down in autumn. Tree peonies (Paeonia suffruticosa), are a shrubby deciduous plant that grows about 1m tall. They can take up to 10 years to reach full height and do not die down like their herbaceous cousins. Both types of peonies prefer cool to cold climates.