Best Companion Plants for Peonies

Many gardeners place peonies wherever there happens to be room in a border, then wonder why the flowers are lovely rather than truly spectacular. The secret is often not the peony itself, but its immediate companions: when suitable perennials, shrubs and fragrant plants are planted alongside them, the border can suddenly resemble a professionally designed show garden.

What peonies need before choosing companion plants

To combine peonies successfully, it is essential to understand their requirements first. These perennials appear tough, yet they have definite preferences.

• Position: full sun to light partial shade
• Soil: deep, humus-rich and free-draining
• In winter: no standing water; the ground must not become waterlogged
• Spacing: air around each plant, with no overcrowding

Peonies dislike competition around their roots. Vigorous neighbouring plants that take water and nutrients from them will restrict their growth. If the plants are positioned too closely, moisture remains on the foliage for too long. Fungal diseases such as grey mould can then take hold easily, causing flowers to stick together or rot.

“Peonies flower most beautifully when they have sun, space and leaves that dry after rain.”

To achieve this, follow three straightforward rules when planting the border:

• Select only plants with similar light and soil requirements.
• Avoid placing noticeably taller perennials directly in front of the peony.
• Leave a small “air ring” around every plant instead of packing the area densely with other plants.

Perennials that make peonies stand out

Alchemilla: a delicate veil for large flowers

Lady’s mantle (Alchemilla) is a classic companion for peonies. It forms low, dense cushions of rounded foliage, topped from early summer with clouds of pale green flowers. This very contrast makes the large peony blooms appear brighter.

Pastel varieties, such as pink or cream peonies, look considerably more vivid against lady’s mantle’s slightly neon-green flowers. The plants barely compete with one another: lady’s mantle remains relatively low, so it does not deprive peonies of either light or space.

Bellflowers for airy touches of colour

Many bellflower varieties stay compact, making them well suited to the front of a border. Their bell-shaped blooms extend the flowering season and introduce blue or violet shades, which work exceptionally well with pink and white peonies.

Some bellflower species are more likely to attract aphids and other pests. That need not rule them out, provided they are combined with fragrant “guards” – more on those later.

Hydrangeas as a calm backdrop

Hydrangeas planted at the back of the border add structure. Their large, rounded flowerheads echo the shape of peony blooms and heighten the impression of a lush sea of flowers. The key is to position hydrangeas behind the peonies with adequate distance between them, rather than directly alongside them.

When placed correctly, they provide slight, localised shade during hot summers without depriving the perennials of light altogether. This creates a layered picture: rounded peony blooms at the front, hydrangea flowerheads behind them, and loose filler perennials in between.

Flowering succession: keeping the border in bloom from spring to late summer

A peony border has the greatest impact when there is always something happening around it, both before and after the main flowering period. A well-planned succession of blooms ensures there are no empty gaps.

Bulbs and perennials before and after peony flowering

• Bearded iris: Usually flowers shortly before peonies, opening the season.
• Ornamental alliums (Allium): Produce spherical blooms, often at the same time as peonies or immediately afterwards.
• Daylilies (Hemerocallis): Take over in high summer and provide the second major burst of colour.

By mixing these plants thoughtfully, you create a kind of “wave of flowers”: iris first, followed by peonies, then alliums and finally daylilies. The border therefore remains attractive from April to August without the need to keep adding new plants.

“The aim: no bare spell in the border – every plant takes the leading role in its own time.”

Lavender and other protective plants for natural defence

Appearance is not the only consideration: protecting peonies also matters. Certain plants act as a natural barrier against pests and damage caused by wild animals.

Lavender as a fragrant protective wall

Lavender is ideal along the sunny edge of a peony border. It thrives in free-draining soil, requires little maintenance and prefers relatively dry conditions. Most notably, its essential-oil fragrance keeps many unwelcome visitors away.

These include:

• Mosquitoes
• Flies
• Fleas and moths
• Some sap-sucking insects
• Wild animals such as deer, which often avoid the scent

Planted in a row along the border’s edge, lavender forms a fragrant barrier around the peonies. Its blue-violet colouring also harmonises beautifully with pink, white and red flowers.

Ornamental alliums: decorative and useful

Ornamental alliums do more than bring graphic spherical flowers to the border: they also release a mild onion-like scent. Many insects and some rodents dislike this smell. This gives Allium a dual purpose, as both an ornamental plant and a guard.

Together with lavender, it creates an unusually effective protective belt – especially where more sensitive plants such as bellflowers are included in the border and may attract pests.

Common mistakes when selecting plants around peonies

Planting simply “anything pretty” beside peonies often leads to unexpected problems. Some plants are poorly matched to them by nature.

Overpowering grasses and thirsty plants

Very vigorous ornamental grasses can simply smother peonies over the years. They develop dense root systems, occupy valuable space and draw heavily on water. As a result, the peony may struggle, flower less well or collapse more easily after rain.

Perennials that need permanently wet soil are equally unsuitable. They encourage a damp microclimate in which fungal diseases spread more readily. Peonies then effectively have “wet feet” almost all the time, which they strongly dislike.

A crowded border without air circulation

A densely planted border may look magnificent in its first year, but it causes problems later. When leaves cannot dry after rainfall, fungal issues occur much more frequently. Peonies in particular, with their large flowerheads, need enough room for air to move through them.

Good companions	Difficult companions
Lady’s mantle	Vigorous giant grasses
Bellflowers (compact varieties)	Perennials for permanently wet soil
Hydrangeas set back at a distance	Shallow-rooted plants that crowd everything out
Ornamental alliums, bearded iris, daylilies	Densely planted, tall perennials directly in front
Lavender as edge planting	Thirsty summer flowers with no tolerance for dry spells

Practical example: what an ideal peony border could look like

A simple layout for a border beside a sunny house wall or at the edge of a terrace:

• At the very back: a loose row of hydrangeas to form a calm backdrop.
• In front: two or three groups of peonies in a slightly staggered line.
• Between them: islands of lady’s mantle and bellflowers for fullness and colour transitions.
• In front of and among the perennials: several ornamental allium bulbs and bearded iris for the early season.
• Right at the front edge: an unbroken row of lavender to create a fragrant, protective border.

This arrangement produces a border that remains lively from spring through to late summer, attracts fewer pests and naturally directs the eye towards the peonies.

Why companion planting with peonies works so well

Peonies naturally bring size, form and presence. They are the “leading actors” in the border, while many other perennials serve more as supporting players or background figures. Using this division of roles deliberately creates a harmonious garden composition.

The major advantage is that peonies are long-lived, improve with age and require very little care once they are in the right location. Anyone who gives proper thought to their companion plants at planting time can enjoy a border that almost looks after itself for many years.

Those new to the subject can begin on a small scale: a group of peonies, lavender around the edge, lady’s mantle in front and a few allium bulbs. Even this simple combination demonstrates how greatly the right companions can enhance the floral splendour of peonies.