Tree & Herbaceous Peony Cultural Notes
Unpack Peonies Immediately & Plant
Position – Full Sun. Part Shade in hot regions (ie. filtered light between 1-5pm). Requires 4-6 hours of direct sunlight daily. Plant in well drained & raised flower beds. In very hot regions planting in large pots is beneficial as these can be moved out of the hot sun after flowering, during the mid to late Summer heat.
Soil & Planting – Loamy humus-rich soil with a drainage depth of 45-60+ cm. Ph of 6.5 to 7.5 (Neutral). Dig a large hole up to 45 cm x 45cm. If some good topsoil can be salvaged, set it aside and discard the subsoil. Next, mix well-aged compost with topsoil to make the back fill mixture. Note: do not use fresh manure as it burns the tender new roots. Also avoid sawdust or bark dust as they leech the soil of nitrogen. If planting in heavy clay soils, do not blend sand for drainage as in the summer this sets like concrete. Also be aware that digging a hole in heavy clay can form a pool in the bottom where water cannot dissipate quick enough and too much moisture around the roots is detrimental to the peony. In this circumstance plant in a bed on a slope or in flat beds, add extra soil to raise the bed up to 30cm high above the natural soil level to provide that extra drainage depth.
Tree Peony Planting.—Backfill a small proportion of the soil mix and build a soil cone in the center of the hole to support the stem, with roots fully extended downwards around the cone into the hole. When planting out, inspect the roots and if they appear dry soak in a bucket of water for 3-5 hours prior to planting. Take notice of last season’s soil mark on the collar of your plant and plant this collar 5-8cm below the surface leaving some stem or tip growth above the surface. This may bury a couple of active buds on the stems beneath the surface, which will multi-shoot to form more branches. Back fill the remainder of soil and firm to remove air pockets. Dressing of dolomite lime is beneficial on the surface before mulching.Mulch to retain moisture.
Herbaceous Peony Planting—Place pink buds upward with root facing downward or slightly lateral. Buds should be no more than 2.5 to 5cm below the surface of the soil. This includes any mulch. If planted too deeply herbaceous peonies may not flower well. They need to experience the winter cold near the surface of the soil. Dressing of dolomite lime is beneficial on the surface before mulching. Place a garden stake to mark where you have planted your peony so as not to tread on and damage buds during dormancy.
Pots or Urns – Minimum volume 50 x 60cm or half wine barrel size. A good tip is to allow 5-10cm between the soil and the rim to allow for mulch and feeding.
Space – Plant 120cm apart, as roots can grow up to 100-150cm.
Watering – In annual rainfall areas above 24 inches (600mm), it is usually not necessary to water. Water regularly in long dry periods. Remember, too much moisture is detrimental to the plant.
Fertilizing – Fertilize 2-3 times annually, first in late Winter to early Spring (this is when the leaves start to form) giving a light feed with manure/mulch up to 2cm thick but not in direct contact with stems or branches. Add 1 tablespoon of 1-3 month Osmicote or Rose Food and in acidic soils add dolomite lime. Repeat again after blooming (around Christmas) and then give it its heaviest feed in early Autumn. It helps to have a pH test kit to know if and how much lime to feed the peony. Use organic fertilizer, compost or well-rotted manure. Small amounts of potash in Spring can help older plants flower. Using Dynamic Lifter or chook-pooh tends to promote tall week stems and very few flowers. Over feeding a young peony can also produce weak stems. Sometimes a hard, slow growth for these plants gives the best results in producing a healthy, sturdy, mature plant.
Blooming – October to early December. Some peonies flower earlier than other varieties. Plants three years old or older plants are capable of blooming the season after planting out, though often the flowers on more complex bloom forms are small or distorted until the roots have established. There is an old Peony saying – “the first year it sleeps, the second year if creeps, then the third year it leaps.”
Climate – Peonies tolerate a huge variation in climate, with the exception of tropical and desert zones. In general the colder the autumn-winter the more prosperous the peony will be. Tree Peonies benefit if they grow in frosty regions and may produce more flowers and/or larger blooms in comparison to plants in a more moderate or frost free climate zone. In very hot/dry regions some extra care is necessary to shelter the plants over mid to late Summer and also increase the frequency of watering.
Growth & Lifespan – Tree Peonies are long-lived plants and most varieties make only a few centimeters growth each year. They do not form “trees” as such but more of woody shrub with a spreading habit. In fact growth after 5-8 years may only be 0.6m x 0.6m most varieties are capable of reaching 90cm in height. A few are able to grow up to 1.2 to 1.6m after 20+ years. Chinese Tree Peonies can live more than 100 years and in China there are Tree Peonies over 700 years old.
Growth & Lifespan – Herbaceous Peonies are long-lived plants and form a large crown just below the surface and thick fleshy roots deep below the surface. New leaves and flower stems begin to emerge by late July, August. All peonies are best left undisturbed if they are performing well.
Pruning – As Tree Peonies are slow growing pruning is generally unnecessary. Only cut back dry or dead flower heads to the first bud. In Winter remove internal dead growth and finished leaf axils, if unsure, leave it. Unlike roses, peonies do not increase vigor or produce shoot’s more when cut back.
Pruning – Herbaceous peonies require old spent leaves & stalks to be cut back to within 5cm of the soil each year during March-April or when they become dry and unsightly.
Pests and Diseases – Peonies are subject to very few diseases. Peony botrytis is caused by humid conditions – this is controlled by the application of a fungicide such as Mancozeb or Daconil. Peony wilt is controlled by cutting off and safely disposing of the affected leaves. (Do not recycle into compost).