Growing Instructions for the Home Gardener
Peonies are large, lovely, luscious flowers. Whoever saw a peony that wasn't beautiful? They are surprisingly hardy and easy care also. They thrive in frosty cold and require some cold to flower successfully. They are also surprisingly drought tolerant through the summer. Given a little care, most peonies will grow happily in the same spot for many years, becoming heirloom plants by which the garden is remembered long afterwards.
Herbaceous peonies die down every Autumn. Different varieties pop up through the ground in spring (September) at different times. Do not panic if one variety is three or four weeks later than another. Most varieties flower for about two weeks between late October and early December. Do not expect too much in the first year. There may be only one or two stems, and the flowers may be absent, small or atypical. In the first year, do not cut the stem off for cut flowers, since stems do not regrow during the season.
Most varieties make excellent cut flowers but, like roses, are best cut in the bud stage (when soft but not opened). When mature (usually by the third year), do not cut more than about a third or at most half the stems for cut flowers. Disbudding side buds will increase the size of the main flower. Alternatively, leaving the side buds prolongs the flowering display time.
NEVER cut the foliage down after blooming, but leave until it turns colour in the autumn. Cutting down to ground level and burning or removing the foliage may help prevent carry-over of some fungal infections.
Autumn is the best time to plant bare roots. This gives time for feeder roots to develop during the winter
before top growth commences. Peonies in pots can be planted during the growing season.
The site should be sunny & well drained. One or two varieties are shade tolerant. Although a deep fertile soil is best, peonies can still do well in quite poor soils, as long as it never becomes water logged (especially winter).
Allow an area of 1 sq. metre when fully grown (i.e. at about 3 years). Peonies resent trees or shrubs being too close to them, or even overhanging branches. This is probably the most common reason for failure to thrive. Small annuals close to them are all right.
It is important to plant herbaceous peonies at the correct depth. With bare roots, find the uppermost bud on the crown and plant so that the base of that bud is 5 cm (2”) from the soil surface. With POTTED herbaceous peonies work out where the uppermost stem joins the brown root and have the soil surface 5 cm (2”) up the stem. The level of the settled potting mix may not be exactly the same as the desired soil planting level. The planting depth for potted tree peonies and intersectionals (Itoh) hybrids is not so critical and the level of the potting mix in our pots is probably a good enough indication.
With all POTS blend the upper loose mix with the soil. The lower area will contain feeder roots which are treated more carefully. The bare root is not generally planted vertically but is normally angled downwards at an oblique angle from the horizontal.
Mark the site with a permanent marker so as to keep well away from the crown when hoeing weeds.
Cultivation is probably the best form of weed control. Bark mulches can be used but straw and compost
increase the risk of botrytis (keep it away from the crown).
Peonies, like all plants, respond to fertiliser but are not gross feeders. If you don’t know the specific needs of the soil from testing, use a general garden fertiliser like Nitrophoska Blue Extra (with trace elements) in the winter before sprouting commences. Don’t put fertilisers in the planting hole.
Watering, even in dry climates, is seldom needed if planted at the correct time. Judicious water occasionally in spring will help to increase bloom size. An occasional deep soak is better than many small shallow ones.
Some varieties need to be staked for a good garden display.
Botrytis (grey mould) and Xanthomonas (bacterial blight) are the two most common diseases. The most important method for the home gardener controlling these and other diseases is to cut down and completely remove dead foliage in autumn. (Don’t cut down Tree Peonies – the stem above ground remains alive – only remove leaves.) Also timely removing of diseased foliage during the growing season will help greatly. Fungicidal sprays like Captan/Carbendazim, Rovral, Bravo, Switch and Scala and bacteriostatic sprays like Copper can be used but gardeners often get away with little or no spraying.