PLANTING OF HERBACEOUS PEONIES & ITOH GROUP HYBRIDS
Fall is the best time to plant bare root peonies...
and any time from September until the soil is frozen is considered acceptable. Earlier in this time frame is better than later, so upon receipt of the order, plant immediately. If you can’t plant right away, keep the box in a cool, dry location. The peonies can stay in their shipping packages for a few days if necessary. Potted peonies are often available at nurseries and garden centres throughout the growing season. These can be planted any time while making the effort to minimize root disturbance as much as possible. It is still preferred to sink the pot in the garden and then plant the peony in the soil come fall. Itoh Group hybrids (between herbaceous and tree peonies) offer you flowers and foliage typical of tree peonies, but the advantage of the plant habit and hardiness of herbaceous peonies.
Herbaceous peonies generally require a sunny, well drained location, but full sun as found in an open field, is seldom an absolute requirement. Some shade, especially in areas that have very hot dry summers, is beneficial in prolonging flower condition. Don’t plant your peonies too close to shrubs or trees because they will compete for soil moisture and nutrients. Choose a well drained site for your peonies. Standing water is the number one enemy of a peony! Herbaceous peonies are heavy feeders and enjoy a heavy fertile soil. They seem to do better in heavy soils than in sandy soils. The trick however is to ensure that drainage is impeccable. SOIL PREPARATION
When preparing a new bed for peonies, dig the soil as deeply as possible and add well aged compost if your soil needs improving. The addition of compost is particularly important if your soil is sandy. Be aware however that fresh manure is not recommended as it is reputed to burn young plants, but well aged, composted manure is entirely safe to use. Once the soil has been prepared, tamp it down slightly to help ensure the peonies don’t sink when planted. It has long been recommended that individual peonies be planted in holes about two feet deep and two feet wide, but your own site conditions will dictate how much digging and soil improvement is needed. Proper amendment of questionable soils prior to backfilling will ensure that your long lived peony will continue to perform well for years. If you are lucky enough to have good garden soil, you may not need to do more than dig a hole sufficiently large to hold the roots of your division.
Depth & Spacing
The depth of planting is important. Too deep planting is one of the commonest causes of failure to flower. A peony division is made of three parts, the eyes (or buds from which the next year stems will develop), the crown (from which the buds grow) and the roots. Crown tissue is not readily distinguishable from the root, so the eyes are used as a guide in planting.
In herbaceous peonies the eyes are always on the crown, but on Itoh Group peony divisions, the eyes may appear on the crown as well as on the stems. This entails slightly different planting philosophy in which the division is placed such that all visible eyes are between two and four inches deep, and the roots are pointing downwards.
In herbaceous peonies the crown should be about 2 inches (5 cm) below the ground surface. There will be eyes, usually pink, growing from the crown and planting depth is measured to the crown at the base of the eyes. Much deeper and the peony may not flower. Any shallower and the crown may be damaged when working in the area. Be aware that if you dig a deep hole, there may be settling resulting in your peony being deeper than intended, so plant shallower in the expectation that the division will settle down to the desired depth. Water after planting only if the soil is dry. Peonies should be spaced about 3 to 4 feet apart (1- 1.3m). There are dwarf varieties that can be closer than this.
Mulch helps keep the weeds down as well as retain moisture in the soil. Because peonies don’t like excess moisture on the crown area, avoid putting the mulch directly on top of the crown. In areas where the winter brings little snow and many freeze thaw cycles, after the ground has frozen place a few branches over the newly planted peonies. These, particularly if from evergreens, will trap eaves and snow providing a natural mulch which helps to prevent frost heaving. Many gardeners will use a conventional mulch instead, but make sure to remove this from the crown area as soon as danger of heaving has passed and new growth is seen. If you experience frost heaving do not push the peony back down into the soil but rather build up the soil level around it. This helps preserve some of the essential feeder roots. After the first winter the plants should have sufficient root mass to resist frost heaving and the branches are no longer required.
Never, ever, cut down the foliage right after flowering, as you are removing the ability of the plant to make and store food reserves it needs for next year’s early growth and flowering. Allow the foliage to remain on the plant until touched by frost. Peony foliage continues to look good after flowering, and many peonies have foliage that turns colour, providing some fall interest in the garden. In the late fall cut herbaceous foliage to an inch (2.5 cm) above he ground, but leave the Itoh Group hybrids at about four inches (10 cm). Remove the foliage from the garden since it can serve as a haven for various fungi. Removal of foliage reduces the chances of future fungal attacks by eliminating many of the overwintering stages of the fungal organisms.
Spent flowers can be removed or left on, as you like. Some peonies, especially he singles and semi-doubles, will produce very decorative seed heads after flowering. If you are collecting peony seeds, they are ripe just when the pods begin to open in the fall. Peony cultivars do not come true from seed but seeds can be planted and many ill germinate and grow, potentially giving new varieties.
If your peonies are planted in a soil with a high clay content i.e. a heavy soil, you may not need to be overly concerned with fertilizing your peonies. In sandy soils periodic top dressing with well aged compost in the fall helps maintain soil fertility. Apply the compost around the peony but not directly on the crown. You can also use non-organic fertilizers as long as the amount of nitrogen is lower than the phosphorous and potassium. A ratio of 1:2:1 (Nitrogen: phosphorous: Potassium) is often recommended. There are no fertilizer recommendations that are applicable to all situations, but if you feel you have to fertilize, apply a half cup of 10-15-10 in early spring and another half cup just after flowering.
Established peonies are reasonably drought resistant. If the first spring after planting is very dry the plants will benefit from receiving some water. Drip irrigation is always preferred to overhead watering as it reduces the chances of fungal diseases.
For a brochure of the above information:
Planting of Herbaceous Peonies & Itoh Group Hybrids
Prepared by: The Canadian Peony Society
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