A comprehensive guide to growing and caring for paeonia (peonies).
PAEONIA
(Common name: Peony / Peony rose)
FAMILY — Paeoniaceae
LIFESPAN — Herbaceous perennials or deciduous shrub (species dependant)
ASPECT — Full sun or partial shade.
PLANTING ADVICE — Prefers a cold winter to flower well. Ideally 2-3 ground frosts in winter – the more the better. Don’t like to be moved.
SIZE — 0.5–2.4m tall
WHEN TO PLANT — Autumn (preferably)
SOIL TYPE — Moist but well-draining soil, rich in organic matter.
PEAK FLOWERING — Spring
For timeless elegance in your garden, peonies are are gorgeous choice. Peonies are spring favourite for florists and gardeners alike. Their large and enchanting blooms are truly captivating, in the garden or in a vase.
Growing peonies is a super rewarding experience, and doesn’t need to be hard if you follow the right advice.
Together with NZBulbs, we’ve put together this guide with essential steps and know-how to successfully cultivate peonies and enjoy their beauty year after year.
Late autumn to early winter is the best time to plant peonies.
Types of Peony Plants
Peony plants come in three different types:
Lactiflora — Paeonia lactiflora (Chinese peony): Lactiflora is Latin meaning ‘milky flower’ – named because the originals of this type of peony were a milky white colour. Lactiflora peonies originate in central and eastern Asia and are often known as herbaceous peonies. They are usually (but not always) fragrant and form bushy plants that die back completely in late autumn before re-growth in late winter to early spring.
Tree Peonies — Paeonia x suffruticosa: Tree peonies are native to China and are deciduous woody plants which retain a woody structure even when dormant in winter. A tree peony has large, usually fragrant flowers and flower earlier than lactiflora peonies. Despite their name, they do only grow to 110-130cm.
Intersectional Peonies (Itoh Peonies) — This type of peony comes from crosses between lactiflora and tree peonies. They are known as Intersectional Peonies or Itoh Peonies – named after Japanese horticulturalist Toichi Itoh, who was the first to succeed in creating these hybrids. Itoh peonies are very similar to lactiflora peonies in size and form, and they also die back completely from late autumn. But they have sturdier, strong stems – more so than the lactiflora types and are the last of the three types of peony to flower in late spring – early summer.
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You can find lactiflora peonies and some Itoh types for sale at NZ Bulbs.
Peonies thrive in cold winters.
Peonies are easy to grow and don’t need too much care or attention.
Growing Conditions for Peonies
Though peonies thrive in cold winters, they can be grown successfully anywhere that has two to three ground frosts in winter – the more the better. They are also very drought tolerant in summer.
For warmer climates — If you don’t get the required ground frosts but still want to grow peonies, it just takes a little extra work. The trick is to place ice on them in winter to give them the necessary cold. The best way to do this is by freezing water in a strong plastic bag. Place the bag over the crown of the peony in the evening – the bag will prevent the ground becoming saturated as the ice melts. Repeat this several times during winter.
Peonies need at least six hours of direct sun to flower well.
Tips for Planting Peonies
Peonies are easy to grow and require little care or attention.
WHEN TO PLANT PEONIES
Late autumn to early winter is the best time to plant, to allow time for roots to develop before the top growth starts. They can be planted in your garden or in large pots or tubs. If using tubs or pots, they should be large – the plants can grow up to a metre wide and tall so will easily topple in windy conditions if they are not planted in your garden or a fairly substantial pot. The roots can become quite large after several years in the same position and garden or large tub planting allows more room for these to grow.
WHERE TO PLANT PEONIES
Choose somewhere sunny and well-drained to plant. Peonies need at least six hours of direct sun to flower well, and ideally all-day sun. The same open garden position that will give the best sunshine is also much the same position that will allow the best frosts as they will be away from other plants which may shade or shelter them. Lack of cold or sunshine are the main causes of plentiful leaf growth but no or few flowers.
SOIL FOR PEONIES
Deep fertile soil is best — though you can plant in most soils as long as it is well-drained soil. Good drainage will mean that the soil won’t become water-logged.
Plant peony roots (thick-rooted tubers that act like bulbs) at least one metre from other plants so they are not crowded by trees, shrubs or other peonies. By the time they’re fully grown (mature plants are around 3 years old) they like to have at least a metre of free space on all sides.
There is no need to fertilise peonies when planting: Fertilising after planting is largely a waste of fertiliser, the tubers have all the energy store they need to start off their growth.
PEONY PLANTING DEPTH
Plant 3 to 6cm below the soil surface – the depth depends on your climate. In cold climates and frosty areas, you can plant with 6cm of soil above the tuber as the cold will still easily find its way down that far. In areas that get only light frosts, or no frosts and you’re icing the tubers, plant with only 3cm of soil above the tuber to ensure that the cold temperatures from frosts or ice reaches down far enough. Use a ruler to check if necessary.
Peonies don’t often need to be watered as they are very hardy.
Peony Care Through the Seasons
Peony care during the growing season:
Watering:
Peonies don’t often need to be watered as they are very hardy. But never let them go completely dry during their growing period of late winter to late summer.
Fertilising:
If you’re one for fertilising your garden, the best time to fertilise is in spring and early summer when the plant is actively growing. Take care to use a fertiliser that is high in phosphate and potassium and low in nitrogen. Too much nitrogen will promote peony foliage and peony leaves to growth, at the expense of blooms.
Disease:
If growing conditions are damp and warm you might need to apply a fungicide to prevent or treat Botrytis (grey mould), the most common fungal disease to affect peonies. It can cause leaves to blacken and peony stems to rot near the ground level.
Thrips:
Sometimes thrips (small sap-feeding insects) might attack your peonies. Usually thrips will do their damage early in the season by tapping into the sap in the soft developing flower buds, causing dry and distorted flowers when they open. Keep an eye on your plants and spray with a suitable insecticide if necessary. Natural neem sprays are effective if started early enough.
Flowers:
Peonies will flower from late October to early December (Southern Hemisphere). Flower production varies a lot between varieties — how happy the plant is in its location, and the age and size of the plant. Newly planted tubers should produce anywhere from 1-3 flowers in the first year, increasing to 20 or more blooms for large established plants. Peonies make beautiful cut flowers!
Peonies will flower from late October to early December (Southern Hemisphere).
Peony Care After Flowering
Do not trim or remove any leaves after flowering. Peonies need their leaves to build strength for the next season — they are the ‘solar panels’ powering tuber production. Leave the plants to grow until they lose their leaves in late autumn, at which time you can cut the plants down at the base of the plant to ground level and remove all the top growth to prevent any fungal infections, such as botrytis, from wintering over on the dead material.
Propagation: Dividing Peony Tubers
Tubers are slow growing but can be lifted after three to four years and will be large enough to be divided into two or three pieces after that time. Use a sharp knife or fine-toothed pruning saw to divide the tuber, keeping some of the central crown with each portion. You can replant the divided pieces right away if you want to. The divided pieces will take a few years to settle in, just like the original piece planted, so you will get fewer flowers for a few years after dividing.
Peonies can be lifted and divided after three to four years.
Troubleshooting: Lack of beautiful blooms?
There are several reasons you might not be able to grow peony flowers. Here are some common problems:
- Depth. Peonies need to be planted at the right depth to produce beautiful flowers. They won’t flower if they’re planted too deep.
- Sun. You will struggle to get peony blooms if they’re in the right location for sun. Full sun is ideal.
- Fungal disease such as botrytis blight.
- Thrips.
- Shocked. After root division or transplant your peony it can take two or three years to feel settled enough in its new spot. If you’ve followed the planting tips above, then a bit of a time should help it re-establish and produce flowers again.
- Extreme weather. A very dry summer may result in fewer flowers the following year. So, keep an eye on your plants in droughts.
- Late frosts. Peonies like cold weather, but not when they’re about to flower. A hard frost when the peony buds are already developed can damage or destroy the new buds.
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