Peonies are among the most beautiful and long-lasting flowers you can include in your garden – they produce brilliant flowers to last a lifetime and can bloom for over 100 years. If you’re creating a rock garden, you may be wondering if you can incorporate these beautiful, long-lasting flowers into the landscape – and you can!
Some peonies can grow in a rock garden. Species native to rocky woodlands and mountain steppes are ideal for rock gardens, while others require more space and moister soil to grow.
So, how can you tell if a peony will be happy in your rock garden, and what species are best suited for rocky terrain? In this article, I’ll give you all the answers you need and teach you how to determine if a peony can grow in a rock garden. I’ll also give you some information about the peony species best suited for stony beds and offer you some tips for cultivating these brilliant blooms in rock gardens.
How to Determine if a Peony Can Grow in a Rock Garden
When determining if a plant will grow well in a rock garden, there are a few questions you should ask yourself.
- How strong are the plant’s stems?
- Does the plant grow in rocky soils in the wild?
- Does the plant grow deep, with wide roots, or will it do well in a contained space?
- Is this plant drought-resistant, and will it grow well with the additional drainage that rocks provide?
If you find that the cultivar or species you want to plant has hardy stems and grows in mountainous climates with rocky soils, ample drainage, and confined spaces, your plant will likely thrive in a rock garden.
Luckily, some peonies fit this description to a T – however, as mentioned above, not all peonies do. So, you will first need to evaluate each peony’s ideal growing conditions before settling on a specific variety.
6 Best Peony Species for Rock Gardens
If you are looking for the perfect peony for your rock garden, look no further. I’ve scoured the details regarding every variety of peony and found those that will thrive in rocky plots. So, let’s take a look at them!
Here’s a list of the best peonies for rock gardens:
- Paeonia tenuifolia
- Paeonia rockii
- Paeonia lactiflora
- Paeonia emodi
- Paeonia anomala
- Paeonia obovata
Let’s discuss each one so you can find the perfect peony for you!
Note: This list will include peony species, not the cultivars of each species. However, the cultivars and sub-species within each group are suitable for rock gardens.
- Other names: Fern Leaf Peony
- USDA Hardiness Zones: 4-8
- Native to: Caucasus mountains in Russia, Ukraine, Bulgaria, Romania, and Serbia
Paeonia Tenuifolia is a herbaceous peony that has unique, fluffy foliage that looks much like the tops of carrots. The flower colors vary, with specific cultivars having red, white, or pink blossoms.
It grows in low clusters, not exceeding 2 feet (0.9 m) tall. These smaller peonies need full sun to partial shade, so they are ideal for bare spots in rocky outcrops where they will get around 6 hours of sunlight daily.
These peonies prefer well-drained soils, so they are an ideal fit for your rock garden. However, their delicate, slender shoots cannot push through surface stones, so they need plenty of clear soil space to come back every spring.
They need compost-based fertilizers (you should never use manure on peonies) and prefer to grow in heavy clay-based soils with sandier or small-gravel topsoil.
- Other names: Rock’s Peony
- USDA Hardiness Zones: 4-9
- Native to: The Gansu Province of China and the surrounding areas
The Paeonia rockii is a tree peony with a sublime fragrance and open red, pink, mauve, fuschia, or red flowers. It can reach a size of 6 feet (1.82 m), and so it is not for small rock gardens.
Native to mountain climates with high elevation and rocky limestone soils, it is a hardy plant that will come back every year, bigger and better than ever.
These peonies grow best in partial shade, so they are perfect for rock gardens placed at the side of your home that only get morning or evening light. They also need humus-rich soil with a pH of 7 to 8.5, which you can quickly improve by adding limestone around the shrub.
The rockii is deciduous, so you must prune it every winter.
- Other names: Chinese Peony, Common Garden Peony
- USDA Hardiness Zones: 3-8
- Native to: Eastern Asia in China, Tibet, and Syria
The Paeonia lactiflora (which means “milk-flower”) is a herbaceous peony with white, pink, or red flowers. In China, it’s known as the king of flowers since it is so beautiful. This peony is also called the “common garden peony,” It is the one we all know by its globe-like round appearance and brilliant blooms.
Because it is herbaceous, it will not grow woody stems, so it can be delicate and is much smaller than the tree peonies. This plant will reach 2 to 3 feet (0.6 to 0.9 m) tall at full maturity.
This peony prefers sandy or loamy soils, so it’s best suited for rocked-in garden beds with loose, well-aerated media and plenty of stone. They need full sun to thrive.
Since this peony is herbaceous, you’ll need to ensure that surface stones do not block the shoots when they come up in early spring. These peonies do not react well when adding manure-based fertilizers to their soil. Only offer these peonies compost, worm castings, or other similar fertilizers.
- Other names: Himalayan Peony
- USDA Hardiness Zones: 7-10
- Native to: Afghan, Tibetan, and Nepalese mountain ranges
The Paeonia emodi is one of the easiest-to-grow peonies. It can grow in practically any soil type, from clay to sandy, and thrives in partial to full shade. Thus, it needs at least 6 hours of sun every day.
This peony is herbaceous, and it’s relatively small, often only reaching heights of 3 feet (1 m) tall. However, some cultivars, such as the very common and popular White Innocence peony, may grow larger.
The emodi is sensitive to overwatering, so it does very well when contained in rock gardens. They are also surface rooters, so you need to plant them very close to the topsoil, making them an excellent choice for shallower rock gardens. These flowers burst back into life every spring as they form their buds underneath the ground in winter.
They are tough to kill, so they are ideal for even the least-practiced gardener.
- Other names: Anomalous Peony, Common Peony
- USDA Hardiness Zones: 4-8
- Native to: Russia, Mongolia, and Northern China
The Paeonia anomala has similar characteristics to the Paeonia tenuifolia. However, this peony has a taproot that extends up to 3.3 feet (1 m) deep into the soil, which means it is not ideal for shallower rock gardens. It does best in rocky outcrops and rock gardens with no barrier underneath the bed.
The peony itself is herbaceous and can reach heights of ½ ft (15.2 cm) tall. The flowers have a fragrant, sweet smell, and the petals are usually pink or red, with some rare varieties having white flowers.
Like most other peonies, this species can grow in almost any soil with ample drainage. It also thrives in full to partial shade.
- Other names: Woodland Peony
- USDA Hardiness Zones: 5-8
- Native to: China, Manchuria, Korea, Japan, and Russia
The Paeonia obovata natively grows in woodland areas in rocky clearings. Most of the time, these peonies have white, red, or light purple flowers with a fragrant sweet scent.
The obovata is an herbaceous perennial that grows best in partial shade. It’s a small variety, often only reaching 2 feet (0.6 m). These peonies are resilient in any well-draining soil, so they do very well in rock gardens of any size.
Tips for Planting Peonies in a Rock Garden
Before you plant your peonies, there are several things you should know about how to best care for these flowers in rock gardens.
Here are some tips you should follow to ensure that your flowers bloom every year:
Keep Surface Rocks Away From Stalks
Don’t let surface rocks get too close to the stalks and sprouts. Most peonies aren’t strong enough to push through dense surface stones when they come back in the spring. So, create a bare circle around the peony plant and edge it with plastic or a stone barrier to ensure that the peonies can grow.
Never Use Manure-Based Fertilizers
Peonies are prone to developing Botrytis Blight (a fungal disease) when fertilized with manure. So, use only organic non-manure fertilizers and compost to fertilize your peonies, and apply it sparingly in the spring as the shoots rise from the ground.
Investigate Your Chosen Cultivar
Although cultivars primarily have similar characteristics as their overall species, many are hybrids, which may have unique care requirements. So, once you find a peony that appeals to you, read up on the care instructions for that plant before you incorporate it into your rock garden.
Plant Your Peonies Near the Surface
Peonies are not very strong when they shoot up in the springtime, and they will only return every year if you plant them very close to the ground’s surface. Plant your peonies no deeper than 2 inches (5.08 cm) from the soil’s surface for the best results.
Some peonies can grow in a rock garden. These peony varieties are native to rocky woodlands or mountainous areas and require partial to full sunlight with well-draining soil.
However, most peonies have very delicate shoots, so it’s critical to ensure that you do not cover the plant with stones or gravel. It would be best if you also planted your peonies close to the soil’s surface since the shoots will not be able to push through much dirt.
In addition, ensure that you never use manure-based fertilizers on peonies since it may introduce infections such as Botrytis blight.