Long-time plant favorites, peonies are show stoppers in ornamental gardens. Some haters may say they’re too big, colorful, or in your face about their beauty. I disagree and routinely fall in love with their blossoms each spring.
Tree peonies, unlike herbaceous ones, grow from woody stems aboveground. They’ll reach heights that herbaceous ones wish they could, from about four to six feet tall. Their divided foliage falls off in winter, but the woody stems sprout new leaves when the weather warms in early spring.
There are three species of tree peonies covered in this piece—nowadays, breeders create hybrids that combine the genetics of all three species. No matter the cultivar, all tree peonies have woody aboveground stems, divided foliage, and giant blooms.
At first, tree peonies look less impactful than herbaceous peonies, but they’ll supersede their beauty after many years of slow growth. Tree peonies take longer to reach their mature size, but the long wait is well worth the stunning results. Select one with flowers of your favorite color—their blooms come in white, pink, red, purple, yellow, copper, and coral.
Tree Peonies Overview
|
|
|
|
What Is It?
The tree peonies we discuss here are three species of deciduous peonies. These three species have different flower colors, habits, and leaf shapes. Hybrids blend the best qualities of two of these tree peony species into one. You’ll be impressed with their cold hardiness and upright shape, no matter which type you select.
Native Area
Peonies originate from Europe, Asia, and western North America. Tree peonies are descendants of wild woody shrubs from China and Tibet. Growers select them for flower color, structure, and leaf shape. The types that end up in nurseries are the best selections, as they’re proven to grow well in gardens despite difficult conditions.
These flowering varieties receive consistent moisture, direct sunlight, and plenty of organic matter in their native range. Simulate these conditions in your landscape to grow your biggest, most beautiful peonies yet.
Characteristics
These are the three common tree peony species. Most hybrids are a mix of these types, sharing qualities between different species.
Paeonia x suffruticosa
This is the most common of all tree peonies, with many hybrids having single or double-petalled flowers in pinks, purples, whites, and reds. Flowers reach six to eight inches across, and their centers have many stamens and pistils for pollinators to explore. This type adapts well to garden conditions and is a good choice for beginner peony growers.
Paeonia delavayi
Another unique tree kind is Paeonia delavayi. These types grow between three to five feet tall, with a wider range of flower color than P. x suffruticosa. Peonies in the delavayi species sport yellow, red, white, orange, and purple flowers. They reach three inches across, with multiple petals and varied color combinations.
Paeonia ludlowii
The last common type is the Tibetan peony, Paeonia ludlowii. It also goes by the name Paeonia lutea var. ludlowii. I grow this one in my Pacific Northwest garden in a raised bed. It loves the winter rain and summer sunshine here. Its flowers are smaller than most peonies, although they bloom yellow blossoms in abundance on shrubs that reach nine feet tall! This tree peony is the tallest of these three common species.
Planting
Tree peonies thrive in the ground and raised beds or containers. Containers must be at least two feet deep—tree peonies survive winter by growing long roots. Mature specimens may need transplanting into larger containers; do so during autumn. They reach deep in pursuit of moisture, warmth, and nutrients. If growing them in raised beds, ensure the beds don’t have a barrier between the ground and their bottom.
All three tree species and their hybrids appreciate fertile, free-draining soil. Add compost or organic mulch to your site before planting, and amend soils each year thereafter. They need high levels of phosphorus to set gigantic, unfurling blooms. Some extra low nitrogen fertilizer before and after flowering also ensures plants stay in tip-top shape.
Growing from Seed
Species tree peonies grow true to seed, and some vary in flower color depending on the seed source. Growing their seeds is a fun experiment for the patient gardener. Seed-grown plants may not flower for many years, although they tend to live longer than grafted ones. You’re out of luck if you want to grow hybrid varieties from seeds, as they won’t grow true to seed. They’ll need cutting propagation or root division if you want extra plants.
Sow tree peony seeds in autumn when they’re fresh. Dry seeds may take up to 18 months to germinate, while fresh ones germinate quickly. Plant fresh seeds in multiple pots with soilless potting soil—something with a mixture of coconut coir, perlite, sand, or similar materials works well. Water the seeds well, then keep them inside where they aren’t exposed to the elements. If you live somewhere with temperate weather, you can keep them in a sheltered area.
They’ll germinate in about six weeks, growing roots in their pots. You won’t see much visible leafy growth on top of the soil, so trust that they’ve germinated. In spring, they’ll grow small leafy shoots. They’re slow to establish, so keep them in their pots for two years before transplanting. Put them in a cold frame, protected porch, or greenhouse during intense winter storms, as they are sensitive to extreme weather in their thin containers.
Sow dry seeds in the same soil mixture as fresh ones and treat them the same. Plant seeds during autumn, and keep the soil moist, not soggy. Instead of germinating during fall, they’ll sit in their pots for up to 18 months. Wait until they sprout, then wait another two years before transplanting them into your garden.
Transplanting
Like tree peony seeds, mature transplants establish well with an autumn planting. The cool, wet weather helps their roots establish before winter freeze arrives. Before transferring plants from their containers to their new homes, you’ll want to prepare the site. Start a month before transplanting, and dig a hole slightly deeper than your plant’s root ball, and as wide. Mix in lots of compost and high-phosphorus fertilizer, then fill the hole.
After a month, the compost blends itself with existing soils, injecting beneficial microbes, insects, and fungi. Dig the hole back up, then take your tree peony out of its container. Rough up the roots, so that when they start growing anew, they anchor onto new soil. Finish by placing the root ball in the hole and then filling it with the soil-compost mix.
Water well, and pat yourself on the back for a planting done well. Tree peonies in the coldest zones may benefit from some mulch during the winter and early transplanting. Set them out six weeks before your first average frost date. Let snow or freeze occur, then place piles of organic mulch around the stems. This insulates them in cold zones three through five, so they sprout anew with leafy growth in spring.
How to Grow
Tree peonies are hardy once they establish themselves. They may need a little care and maintenance in their early lives, but the rewards are fruitful. Tree peonies last in gardens for decades! Give them fertile soil, some fertilizer, and regular water, and they’ll stay strong throughout the growing season.
Light
Light is a tricky condition to get right. Full sun sometimes burns plants, while partial shade sometimes results in powdery mildew. Tree peonies are adaptable, meaning they thrive from full sun to partial shade exposures.
These shrubs won’t experience issues in full sun or partial shade, except during hot summers in zone eight. Give them afternoon shade in this zone, as the afternoon direct sun is too intense for tender tree peony leaves.
Direct sun causes increased blooms, while partial shade leads to fewer. Partial shade plants grow taller and leggier than full-sun ones as they reach further for light. Both conditions work well, depending on the ornamental style you’re trying to achieve in your garden. Tree peonies need at least three to four hours of direct sunlight a day, although they appreciate up to eight hours.
Water
These peony species need regular water during the growing season. This keeps their roots cool despite summer heatwaves and direct sunlight. Regular water means watering once the soil dries on top. Avoid watering if soils are already wet, as this leads to soggy, boggy conditions.
During fall and winter, tree peonies need less water as they enter dormancy. They still need some moisture, though, and will starve in bone-dry dirt. Test the site throughout the winter using a finger or stick test. Stick either into the soil, then pull it up to see if it’s wet. If wet, wait to water, but if it’s dry you’ll want to irrigate.
Soil
All species of peony appreciate fertile, well-draining soil. Compact clay and sandy dirt present challenges for their roots as they struggle to penetrate clay or dry out in sand. Amend soils with organic mulch like compost a month before planting. Continuously add thick layers to the soil surface throughout the tree peonies’ lifetimes. It’ll add drainage, nutrients, and beneficial root bacteria.
Container specimens and raised beds need organic potting soils for peonies. Find a mix with plenty of phosphorus, and your shrubs will bloom aplenty. They also need good drainage in containers. When wet for too long, their roots may rot as they drown under the boggy soil. Perlite, vermiculite, or similar components in your dirt ensure your shrubs never experience this issue.
Fertilizing
These special plants have special fertilizer requirements; don’t worry, we’ll cover them here!
Follow these simple steps for tree peony fertilizing success:
- Apply a regular dose of phosphorus fertilizer a month before planting.
- Feed with low nitrogen organic fertilizer like 5-10-10 as leaves uncurl in spring.
- Feed with low nitrogen fertilizer again after the flowers fade.
- As leaves drop, feed your shrubs with bone meal and phosphorus fertilizer.
Follow this regimen annually, and your tree peonies set blooms, leaves, and stems without issues. If your plants look sickly, with yellowing, chlorosis, or spotting, they may need nutrients.
Maintenance
These peonies need little maintenance; you’ll enjoy dozens of blooms with little work! Simply prune off dead or damaged wood during autumn after the leaves drop. You may also choose to reduce your shrub’s height.
To prune for height, select the tallest branches that grew blooms this season and prune them by half. Prune them above another side branch so they’ll sprout next year with new flowers. Tree peonies bloom on old wood, so you’ll need to leave some wood to ensure flowers next spring.
Propagation
Tree peonies often grow off grafts. Grafts are junctions where the roots of one variety join the top stems of another. With tree peonies, the grafting helps growers produce lots of shrubs in little time. For the home gardener, a graft presents a challenge. You’ll want your shrub to develop its roots over time rather than use ones from a different variety.
Achieve this by burying your peonies at least four inches deep, below the graft union. With time, roots will form off the top stems, and the other type will die back. This also means that the rootstock may send up shoots of its own. Prune any growth that doesn’t match the variety you have, as it’s how peony rootstocks take over.
Now that grafting is out of the way, we can get to propagating! In the same way that growers use cuttings, we can multiply our plant stock. We’ll also discover how to dig up roots and make new plants.
Cuttings
Cuttings are an easy way to create new woody specimens. Start by taking six-inch greenwood cuttings in spring after new leafy growth appears. Strip them of their lower leaves and let a few remain on stem tops. Remove any flowers or buds, then place your cuttings in 5” cube pots with a soilless mix. You can use perlite, coconut coir, vermiculite, or a mixture of these materials.
Water cuttings well, then place them under a humidity dome or a greenhouse. Consistent moisture and humidity help rootless stems stay moist and full of water. They’ll root from between a month to three months later. Leave them in their pots through summer, fall, and winter. They should be safe for transplanting a year after you cut them off their parent plant.
Division
Dividing existing plants is more dependable than propagating cuttings. As their tops go dormant in autumn, their roots begin to grow exponentially. Dig your shrub up after the leaves fall, and divide the plant into multiple ones. Select branches with roots, then slice them apart from other branches. Sometimes slicing isn’t necessary, as some only need gentle untangling.
Once you have multiple stems with roots on each one, transplant them where you’d like. Bury them deep, then water the site well. They’ll pop up in spring with new growth. They’ll likely flower their second year unless they come from especially large specimens. Big stems may bloom their first year.
Popular Varieties
Are you looking for a peony of a specific color? Look no further! These are a few of our favorite tree peonies with gorgeous blooms.
‘Alice Harding’
With full double blooms in bright yellow or white shades, ‘Alice Harding’ is a show-stopping peony. Garden onlookers routinely pause during their tours to gaze into its lovely blossoms. This variety is a descendant of the Paeonia ludlowii species, and it gets its unique yellow flower hue from this type.
‘Alice Harding,’ unlike P. ludlowii, only reaches 30 inches tall. It does spread out wide, so be sure to give it enough free space around its base.
‘Showanohokori’
With pink single-petal blossoms, ‘Showanohokori’ lends grace and elegance to landscapes. The flowers open to reveal red blush spots on the petals’ insides—they draw your eye toward the blossoms’ yellow centers.
This variety opens its flowers fully, which means they have accessible nectar and pollen for local pollinating insects. Plant this variety if you’d like to feed the bees and enjoy its ornamental beauty.
‘Ice Age’
‘Ice Age’ sports double white petalled flowers on dense, compact plants. This variety is small and shrubby, reaching from three to four feet tall in maturity. It works well below taller roses, peonies, or lilacs. Contrast its bright white petals with the light yellow of ‘Alice Harding’ for a wonderful peony design combination.
‘Black Panther’
‘Black Panther’ is a favorite of many peony collectors. This variety sprouts semi-double-petalled red-maroon flowers. They look black under intense sunlight and velvety like a panther’s fur coat. ‘Black Panther’ is a perfect name for this kind, as it hints at its texture and flower hue.
This type reaches four feet tall with lush foliage and plenty of blooms. Give it some space to grow, as it’ll reach up and out as it matures. Plant it with other black flower plants like ‘Onyx Odyssey’ hellebores or similar species to create a goth-style planting.
Common Problems
After they establish themselves, tree peonies experience few issues. They sometimes find botrytis infections outside their native range, although they rebound quickly after a winter dormancy. Two main pests can attack these shrubs: aphids and scales. Banish both these pests and pesky diseases with these tips. However, tree peonies rarely struggle with pests.
Pests
Both scales and aphids are relatively easy to battle, as they die during winter in zones 4 through 8. Scales may overwinter in the soil, although they struggle to survive on leafless tree peonies. Aphids have soft, liquid-filled bodies and freeze at first frost. Keep aphids off your shrubs by spraying populations with strong streams of water. After a week or two of daily spraying, they should disappear from your plants.
Scales are more challenging, and once they establish themselves, they’re difficult to remove. I’ve found they go away if you squish them on the plant and then wash them off. This process is more involved than spraying water, but it works! Remove infested foliage from the garden to avoid scales overwintering near your shrubs.
Diseases
Fungi are fun unless they infect plants! Botrytis is a common fungal condition in peonies that leads to bud black blackening, stem wilting, and black leaf spots. It most often occurs during cool, humid seasons. Watch for gray or black powdery plant parts that turn blacker and rot with age.
Prevent botrytis and fungal issues like canker, leaf blight, stem wilt, and root rot by practicing clean cultural methods. Remove infected foliage from the soil and move it away from your garden. Another good practice is giving your plants proper spacing and irrigation so they experience consistent airflow. If botrytis appears annually, apply an organic copper fungicide this year to reduce its spread.
Frequently Asked Questions
Tree peonies are deciduous shrubs. They lose their leaves during fall but retain woody stems that persist through winter. Out of the stem tops grow new leafy growth in spring.
Plants set too low in the soil, and nutrient-starving plants both struggle to bloom. Dig your plants out and set them higher if they’re too low. Fertilize hungry plants with phosphorus-rich amendments, and they’ll be blooming before you know it.
You should sow them! Look above, under the growing from seed section, to learn more about germinating tree peony seeds.
