From a botanical perspective, the primary goal when selecting companions for Paeonia lactiflora is to create a harmonious relationship through contrasting foliage textures and plant forms. The herbaceous peony itself possesses a distinct growth habit. It emerges in spring with deep red, sturdy shoots that unfurl into large, often glossy, deep green compound leaves. The plant forms a substantial, rounded mound. To complement this form, consider plants with strikingly different foliage. Ornamental grasses, such as Stipa tenuissima (Mexican Feather Grass) or Panicum virgatum (Switchgrass), provide an excellent textural counterpoint. Their fine, arching, and airy foliage creates a soft, moving backdrop that highlights the peony's solid, structural presence without competing for visual attention. Similarly, the vertical, sword-like leaves of an Iris or the broad, heart-shaped leaves of a Hosta offer strong architectural contrasts that make the peony's form appear even more lush and substantial.
The spectacular but fleeting bloom period of P. lactiflora is a key consideration. To maintain visual interest in the border before and after the peonies have flowered, it is essential to incorporate plants with staggered bloom times. Spring-flowering bulbs are ideal precursors. Planting a carpet of small bulbs like Muscari (Grape Hyacinth) or Scilla siberica (Siberian Squill) around the peony's base provides early color. As the peony's foliage develops, it will help conceal the dying foliage of the bulbs. For a post-peony display, later-season perennials take the stage. Plants like Nepeta (Catmint), which blooms for an extended period, or Salvia nemorosa (Wood Sage) can be planted nearby. Their spiky blue or purple flower forms create a beautiful contrast to the peony's large, often double or bomb-shaped blooms, and they will continue to flower long after the peony's petals have dropped, ensuring the border remains vibrant.
A successful plant partnership must be rooted in compatible environmental needs. Paeonia lactiflora thrives in full sun to very light shade, in well-drained, fertile, and moisture-retentive soil. It dislikes having its roots waterlogged and appreciates good air circulation to prevent fungal diseases like botrytis. Therefore, companion plants should share these preferences. Drought-tolerant perennials like Perovskia atriplicifolia (Russian Sage) or Eryngium (Sea Holly) are excellent choices for sunny, well-drained sites. Their silvery foliage and tough constitutions mean they will not require excessive watering that could harm the peony's roots. Similarly, many ornamental grasses are adapted to similar conditions. It is important to avoid aggressive, spreading plants that might outcompete the peony for nutrients and water, as peonies are heavy feeders and can be slow to establish. Plants that require consistently wet soil should also be avoided.
The final layer of selection involves aesthetic harmony, particularly color. P. lactiflora offers a wide palette, from pure white and soft pink to deep crimson and vibrant coral. Choosing companions that either complement or subtly contrast these colors enhances the overall display. For white or light pink peonies, pairing with blue-flowering plants like Geranium 'Rozanne' or Campanula persicifolia (Peach-leaved Bellflower) creates a cool, serene, and classic combination. For the richer red and magenta peonies, touches of silver foliage from plants like Artemisia or Stachys byzantina (Lamb's Ear) can make the flower color appear even more intense and jewel-like. The soft, yellow flowers of Alchemilla mollis (Lady's Mantle) provide a gentle contrast to almost any peony color, and its scalloped leaves catch water droplets, adding another textural element to the planting scheme.
