Delphiniums, with their majestic spires of blue, purple, white, and pink, are cherished staples of the cottage garden border. However, their tall, sometimes leggy form and specific growing needs make selecting the right companion plants essential for a healthy, visually appealing, and structurally sound garden design.
Delphiniums provide strong vertical lines. To create a balanced composition, pair them with plants offering contrasting forms. Rounded, mound-forming plants like Catmint (Nepeta) or Lady's Mantle (Alchemilla mollis) are perfect for softening the base of the delphinium's tall spikes and hiding any bare lower stems. Their soft, billowing textures provide a beautiful contrast to the delphinium's rigid flower spires. For a classic cottage garden look, interplant with Old Garden Roses or Peonies, whose lush, full blooms create a stunning mid-border layer that complements the delphiniums' height without competing with their form.
Companion planting extends beyond aesthetics to improving plant health. Delphiniums are heavy feeders and benefit from companions that do not aggressively compete for nutrients. Low-growing, shallow-rooted plants are ideal. Geraniums (Cranesbill) form a dense, weed-suppressing mat that helps retain soil moisture, a key factor for delphiniums which prefer consistently moist (but well-drained) soil. Furthermore, aromatic herbs like Lavender and Salvia can help deter common pests with their strong scents. Their preference for similar sunny conditions and well-draining soil makes them compatible growing partners.
The iconic blues of delphiniums yearn for complementary and contrasting colors. Yellow Yarrow (Achillea) or Coreopsis provide a vibrant color contrast that makes both flowers pop. For a harmonious, cool-toned scheme, pair with Salvia nemorosa (such as 'Caradonna' or 'May Night') or Veronica spires. To extend the border's interest after delphiniums fade, plant later-blooming perennials like Phlox paniculata or Astilbe (for part-shade locations) nearby. These plants will fill the visual gap left once delphinium blooms are spent.
The hollow stems of delphiniums are notoriously susceptible to wind and rain damage. While staking is often necessary, strategic planting can provide natural support. Dense, sturdy perennials like Russian Sage (Perovskia atriplicifolia) or clump-forming ornamental grasses such as Feather Reed Grass (Calamagrostis x acutiflora 'Karl Foerster') can be planted upwind to act as a living screen, breaking the force of strong gusts before they reach the more fragile delphiniums.
