Peonies! Now is the time!
Fall is the correct time for planting peonies either as bare-root plants, or from nursery containers, in order to give the plants a chance to become established before bloom time in the spring.
It’s All About Good Site Preparation
Peonies have a reputation of being tricky to grow, but the key to healthy and beautiful peonies is in proper placement, and proper site preparation before you plant. Once you have that right, you can step back and let your peonies do their thing, which is to provide us with breathtaking flowers, and in many cases, fragrance.
All peonies are extremely long-lived plants lasting up to 50 to 70 years, so once you get them planted correctly, you will enjoy them for years and years.
Now there are three types of peony: herbaceous, tree peony, and intersectional (which is a combination of herbaceous and tree types), but today we are going to take a look at planting bare-root herbaceous peonies.
If you have never attempted growing a peony before, or you think you don’t have the right climate for it, read on, because we offer a few ideas to overcome problems such as alkaline soils, and warmer climate issues.
We’ll also be troubleshooting some regular problems gardeners have, such as not getting any flowers because they planted their peony too deep. Not to worry, we’ll be covering all that in a minute, but first, let’s take a look at the basics.
Types of Peonies
Today, we are mostly going to be talking about herbaceous peonies and herbaceous hybrid peonies, but just for your information, here is the difference between the three types of peonies:
Herbaceous peonies (P. lactiflora) – die to the ground in winter. They reappear in March, or when the weather begins to warm up, and the snow melts. Lactiflora is the most common species found in nurseries, and most cultivars produce sidebuds.
- Herbaceous Hybrid peonies are crosses between two or more species, which brings additional colors, foliage types, and earlier bloom in the spring, and many produce only one bloom per stem.
Intersectional peonies – are a cross between the herbaceous (or bush) peony and the tree peony. These crosses have produced new, exciting colors. The plants have the lovely leaf form of the tree peonies, but die to the ground in the winter. The plants are strong and healthy with a nice rounded bush form, generally shorter than most herbaceous peonies. Since they are recent introductions and are still in short supply, they command a higher price.
Tree peonies (P. suffruticosa) – have woody stems that lose their leaves in the fall, but the woody stems stay intact. They tend to bloom earlier and with larger flowers than the herbaceous peony. Some are sold as named varieties; however, they are frequently sold by color.
Types of Blooms
There are a number of different types of peony blooms (single, double, semi-double, full double, etc.) and it’s up to you which you prefer. Many are fragrant; just ask your grower for more information, if you’re not sure.
Basic Planting Requirements
1. bare-root plants
2. or from nursery containers
Peonies like half to full day sun. Summer heat is not a problem for the plants; the flowers however, do not last well where the spring days are hot and dry. In those situations, choose an area that gets only morning sun.
Peonis also like regular watering, not soggy or too dry, just regular moisture.
- good friable, slighty acidic, well drained soil. Good drainage is vital to avoid root rot and fungal diseases
- areas that have good air circulation around the plants
- areas that give the plant a cold winter dormancy period
Ideally, if you have the time, try and get the planting site for your peonies deeply dug several days before you actually plant them.
1. Work in plenty of compost, especially if you have a heavy, or clay-based, soil.
- Alkaline Soil Tip: Peonies like a neutral to slightly acidic soil (6.5 to 7.0), so if you have alkaline soil, instead of working in regular compost, work in an azalea or rhododendron soil mixture that is already acidic. Work that in very deeply and well, so as the plant’s roots grow, they will be in a nice acidic environment.
2. While working in the compost, also work in a high-phosphorus fertilizer, like a 3-15-2.
3. Now, allow the soil to settle a few days before planting.
Two inches (5 cm) deep in cold climates (Zones 4 to 7)
One inch (2.5 cm) deep in warmer climates (Zones 8 to 9)
Helpful Tip: Peony crowns have buds which we often call “eyes” and what can look like “pinkish roots” sticking straight up.
When planting, be careful to not touch or bump them because they break and bruise easily. Set the roots so that the tips of those eyes are about one inch (2.5 cm) below the finished surface of the soil in a warm climate.
Carefully check to see that the crown, where the “eyes” of the plant emerge from, is no more than 1.5 to 2 inches (2.5 to 5 cm) below the surrounding grade. If it is planted too deeply, pull the soil covering the crown back to that depth.
Plants are unlikely to flower the first spring after planting, but they should flower every year after that.
Peonies thrive in USDA Hardiness Zones 4 to 7:
Zone 4 (-30° to -20°F) (-34.4° to -28.9° C)
Zone 5 (-20° to -10° F) (-28.8° to -23.4° C)
Zone 6 (-10° to 0° F) (-23.3° to -17.8° C)
Zone 7 (0° to 10° F) (-17.7° to -12.3° C)
But they can also grow and do well in Zones 8 to 9:
Zone 8 (10° to 20° F) (-12.2° to -6.7° C)
Zone 9 (20° to 30° F) (-6.6° to -1.2° C)
If you plant peonies too shallowly in cold weather climates, the crown risks being damaged by winter weather, and any deeper, the plant will spend valuable growing time reaching the right depth rather than producing flowers.
If you plant peonies too deeply in warm weather climates, they won’t get the chilling needed to overcome a seasonal dormancy and to flower properly. There is no well-accepted data available that tells us exactly what the requirement is in terms of temperature and duration.
The factor limiting the success of peonies in warm climates is the requirement for a cold period. Peonies can grow well into USDA Hardiness Zone 8 (10° to 20° F) (-12.2° to -6.7° C).
In addition to that, there is a consensus that weeks of freezing temperatures are not required. There have been several reports from gardeners in USDA Hardiness Zone 9 (20° to 30° F) (-6.6° to -1.2° C) who have grown peonies successfully.
Note: Peonies grown in warm areas will benefit from slightly more shade than those grown in cooler climates.
Care of Peony
1. Light fertilization with a bulb fertilizer, like a 10-20-20 at plant emergence in the spring, and again in the summer after bloom. The main thing is to keep the nitrogen content low. Too much nitrogen causes lots of foliage growth, but doesn’t encourage bloom, so try not to overdo it.
3. Always, maintain only 1 to 2 inches (2.5 to 5 cm) of soil cover over the upward facing growing eyes to make sure your peonies always flower.
4. Protect new growth in the spring from pets and children. New stems are fragile, and the stems coming out of the ground in the wet of spring have a lot of turgor pressure – like when you take a fresh carrot and bend it, it snaps in two. So if you have rowdy pets, or kids, you might want to stake some fencing around the plants for protection.
If you choose not to disbud, you will have a smaller center flower which blooms before the side buds.
If you want, you can cut the center bloom out, and enjoy a bouquet of small side flowers.
Or disbud some and leave some side buds so you can judge how you like them best, or just let nature do what comes naturally.
Again, it’s totally up to you and what you want.
Problems Such as Botrytis Or Buds Not Opening
To prevent Botrytis, allow for air circulation around the plant, and destroy the foliage after fall freezes to reduce the possibility of disease.
Why Peony Buds Are Not Opening
1. Weather: Every variety of peony can respond differently to weather conditions. The most common reason buds fail to open is due to a frost or chill at the wrong time for that variety. A sudden chill at a later stage of development can damage just the inner flower parts, but not the outer parts. This will allow the buds to swell, but the interior tissue to fail and not develop properly. Peonies can be frustrating because some years they can do terrific and other years they do nothing. Meanwhile, continue to water and fertilize and wait until next year.
2. Botrytis is a common problem for peonies in certain climates, especially where a cool damp spring can encourage this fungus. Botrytis causes a fuzzy gray coating on the flowers and often kills the buds. Botrytis thrives in humid conditions and can be avoided or minimized by making sure the peony is planted where it receives lots of sun and has good air circulation. Once the disease is noticed, it is too late to save the buds for that season. Diseased areas should be removed. The whole plant can be treated later in the season with a fungicide such as fungicidal soap.
3. Water: Too much water while the flower buds are developing may cause them to wilt and die, just like too little water. Try to keep the soil evenly moist and make sure the peony is planted in well-drained soil.
Peonies are some of the most fantastic spring flowers you’ll ever have. They make any perennial border a show piece, and if you have never grown peonies because you think you might not have a cold enough climate, or because someone tells you they can’t be grown, try them anyway.
I have grown peonies in climates as warm as Zone 9, and they do just fine. Just follow the extra tips given above, and you’ll not only be able to prove the “naysayers” wrong, but you’ll be enjoying lovely flowers. Good luck!
Hilary Rinaldi is a member of the National Garden Writers Association, a nationally published writer, and a certified organic grower. She regularly speaks and writes about all gardening related topics, with an emphasis on making gardening a successful and enjoyable process for anyone who wants to learn. Weekend Gardener Monthly Web Magazine concentrates of giving detailed gardening tips and gardening advice to all levels of gardeners.