Black-eyed Susans (Rudbeckia spp.) are beloved for their cheerful, golden-yellow blooms and rugged resilience. From a botanical perspective, selecting companion plants involves more than just aesthetic pairing; it requires considering factors like soil conditions, light requirements, root structures, and ecological interactions to create a mutually supportive and visually harmonious border.
Black-eyed Susans possess an upright, clumping growth habit with daisy-like composite flowers held atop sturdy stems. To create a stunning border, we seek plants that offer contrasting forms. Ornamental grasses are exceptional partners. The vertical, fountain-like foliage of Feather Reed Grass (Calamagrostis x acutiflora 'Karl Foerster') provides a sleek, architectural backdrop that allows the bold flowers of the Rudbeckia to pop. Similarly, the airy, cloud-like seed heads of Fountain Grass (Pennisetum alopecuroides) soften the boldness of the blooms and add textural interest that persists into winter. This contrast between the solid, round flower heads of the Susans and the wispy, linear forms of grasses creates a dynamic and layered effect.
A key goal is to extend the visual interest of the border beyond the primary blooming period of the Black-eyed Susans (typically midsummer to early fall). Plants that bloom sequentially ensure a long season of color. For earlier blooms, consider pairing with Catmint (Nepeta), which produces masses of lavender-blue flowers in late spring to early summer. Its sprawling habit also helps cover the base of the taller Susans. To overlap and extend the season, Russian Sage (Perovskia atriplicifolia) is ideal. Its hazy purple spires bloom concurrently with Rudbeckia, creating a stunning color combination of gold and violet that is highly attractive to pollinators. As summer wanes, Sedum 'Autumn Joy' (Hylotelephium 'Herbstfreude') takes the stage, with its broccoli-like flower heads that start pink and mature to a rusty copper, providing fall interest.
Companion planting from an ecological viewpoint focuses on creating a balanced mini-ecosystem. Many companion plants can help deter pests or improve growing conditions. Alliums, such as ornamental onion, are excellent companions. Their spherical purple flowers provide a striking structural contrast, and their pungent scent can help repel aphids and other sap-sucking insects that might otherwise bother the Rudbeckia. Furthermore, incorporating nitrogen-fixing plants like Baptisia (False Indigo) can subtly improve soil fertility for neighboring plants. The deep taproot of Baptisia also helps break up compacted soil, improving drainage and aeration for the fibrous root system of the Black-eyed Susans.
A stunning border relies on foliage as much as flowers. The basal leaves of Black-eyed Susans can become somewhat ragged; thus, low-growing plants with attractive foliage are perfect for covering the ground and providing a "skirt." Lady's Mantle (Alchemilla mollis) is a superb choice, with its scalloped, water-beading leaves that form a soft, lush carpet. The chartreuse flowers of Lady's Mantle also complement the yellow blooms. Similarly, the silvery, felty foliage of Lamb's Ear (Stachys byzantina) offers a cool-toned contrast to the warm gold petals and helps suppress weeds. This emphasis on diverse leaf shapes, textures, and colors ensures the border remains attractive even when few plants are in bloom.
