Cultivation & seasonal care
By Marg Hansen
Peonies need winter cold, rich soil, good drainage and sunshine. They are not hard to grow as long as your climate has a cold winter. You can enrich the soil, alter drainage, irrigate and choose degrees of sunlight for a plant but you can’t alter the climate.
Some growers insist peonies need frosts to develop good flowers but we find long cold nights over many months accomplishes the same thing. Peonies do not like wet feet, so plant them where the rain can drain away quickly. These plants are gross feeders so don’t plant them near trees or bushes which will be depleting the soil of nutrients and moisture.
We grow ours in full sun but if you have very hot summers they may do better if protected from the late afternoon sun to avoid leaf scorch.
Dig a nice big hole and put some compost and old manure in the bottom. If camellias and azaleas do well in your garden sprinkle a handful of lime in as well.
Your new peonies are dormant now. However, once they are planted in moist soil they will quickly send out thin white feeder roots and be well established by Spring. If your area is still dry keep them watered until the winter rains.
It’s very important that you don’t plant them too deep. The top eyes only need to be just below the surface (1″ / 2cm maximum). This is so the crown will get ample cold through the winter. Think of the soil as a doona which evens out extremes of temperatures. With very little soil on top of the crown, it will chill down each evening as soon as the temperature drops. It is the cold which triggers the development of the flower buds.
Mulch has to be carefully managed for the same reason. Pull it well clear of the root run and crown during the winter because it will stop the soil temperature from dropping. By mid-winter, you will probably see some of the pointed red eyes of the buds. It’s very exciting to count them because each one is a stem and the more stems the better. Watch out for snail or slug damage to these buds.
We get lots of sunny days through the winter in Tasmania but the plants seem to know it is still winter and remain dormant.
The peonies quickly shoot, the new growth is very soft and this is a dangerous time for fungus. Mulch must be well clear of the stems because it is very important they are dry. Days of constant rain can quickly rot the stems or leaves, overhead watering can also encourage fungus.
Watch the leaves and stems for dead black or brown spots, sometimes a stem will die at ground level (they look brown and soft). The best cure is hygiene. We remove any leaves or even the entire stem if it shows signs of botrytis. This stops the fungus spores from infecting other stems. If the weather is bad you may have to spray with a fungicide. (Botrytis is mainly a problem that commercial size plantings have to deal with .)
We have very little trouble because the peonies are grown in the open with plenty of ventilation. If you have a warm Spring with days of rain when the leaves do not get a chance to dry off the fungus can grow. Once the stems and leaves have hardened off and become more leathery the fungus danger time has passed.
In the first year, your plants will grow into nice little bushes about 20-30cm (8-12″) high. Each year they will be taller and have more stems. Don’t expect any flowers the first year — it’s better the plant grows bigger. Your aim is to have lots of healthy leaves and keep the bush green as long as possible. Your peony will be bearing flowers for many years once it is big enough.
Water to keep the soil cool and make sure the roots don’t dry out. Now some mulch can help by keeping the root run cool. The leaves will shade the crown but beyond that point mulch is great.
You could apply some fertilizer to the root run during the summer too, and any well-balanced fertilizer would do.
The leaves turn red and brown and when there is no green left you can cut the stems as low to the ground as possible and remove the tops. This is another important example of hygiene. The tops can harbour fungus spores over winter so take them well away. Don’t put them in the compost and don’t burn them.
Weed and fertilize, add lime if necessary. Keep the crowns weed free at all times.