The month of May is synonymous with the short but glorious flowering season of the Peony. There are herbaceous peonies, tree peonies and even the enormously flowered hybrids of the two, but all, if treated well at the outset, will continue to flower for over half a century.
There are a few simple but crucial measures that can be taken to get a strong flowering display, most of which hark back to the planting, which has to be done with considerable thought and care – get it wrong and you’ll be disappointed; get it right and the relatively tough and surprisingly accommodating Paeonia will largely look after itself.
How to grow Peonies
A common cause of a flowerless season is planting too deeply. You should always ensure the ‘crowns’ of herbaceous peonies are not more than an inch below the soil, as they need the coldness of the winter to signal that it’s time to get a move on! Tree peonies can and should be planted a little deeper, as most cultivated plants are grafted onto rootstocks. Therefore, make sure that the graft union is sunk slightly to encourage the grafted plant to form its own roots. Ideally plant both in the autumn when the soil is still warm – this allows them to settle in well before the following spring.
Give herbaceous peonies sun! The more the better, but six hours of it per day if possible for the best flowering display. Tree peonies are most content with dappled sun. For both forms, make sure that the soil is fertile, and free draining to avoid their roots sitting in water. Mixing in grit as well as organic matter before planting can help on the claggier soils.
Food and water
To encourage a strong flowering season, feed peonies the autumn before with a top-dressing of a high potash fertiliser - bone meal is an effective slow-releasing option. Potash will encourage flower production. Don’t overwater! As mentioned previously, peonies don’t appreciate waterlogging and only really need watering in an extended dry spell.
Deadhead when the flowers begin to fade, cutting back to a strong leaf bud. Cut back herbaceous peonies in the autumn and remove the foliage. Doing so discourages the dreaded Botrytis which could lead to Peony Wilt.
Peonies need a little time to mature. The younger (and cheaper) the plant, the more time it needs to develop before a strong display. Savour the short flowering period and make use of cut flowers (although try to resist cutting flower stems in the plant’s first year). Cut long stems when the buds are still quite tight first thing in the morning, and immediately place the stems in cool water. If you want to get the most out of your cut peonies, keep the vase out of the sun in a cool place, and keep everything clean, changing the water daily and removing lower foliage.
Which Peonies to plant
Paeonia emodi (herbaceous)
The early-flowering and delicate white Himalayan Peony.
Paeonia lactiflora 'Jan van Leeuwen' (herbaceous)
A more abundant, stronger white-flowered cultivar. Try Paeonia lactiflora 'Nymphe’ for a good pink, and 'Sarah Bernhardt' for a good double flower.
Paeonia mlokosewitschii (herbaceous)
Difficult name to pronounce, but a beautiful pale-yellow species Peony, whose elegant, rounded leaves make it an interesting foliage plant.
Paeonia ‘Black Pirate’ (tree)
A deep scarlet; or Paeonia delavayi (Tree) which is deeper still.
Paeonia rockii (tree)
Silky white petals with a burgundy base.
The best places to buy Peonies
Binny Plants, East Lothian, Scotland
Specialists who I see at every Great Dixter plant fair.
Primrose Hall, Bedfordshire
Good independent specialist nursery.
Historic Peony growers.
Where to see Peonies in full bloom
Hidcote Manor, Gloucestershire
Until recently, home to the National Peony Collection.
Chelsea Physic Garden, London
London’s oldest botanical garden.
Royal Botanic Gardens at Kew, London
Home to recently re-opened Temperate House.
Cambridge University Botanic Garden, Cambridgeshire
Good for species.
Luoyang Peony Festival every April is an epic event.