Lupines (Lupinus spp.) are a striking addition to any garden, known for their tall, colorful flower spikes and palmate foliage. Beyond their beauty, they play a crucial ecological role. From a botanical perspective, successful companion planting with lupines involves understanding their specific growth habits, nutritional needs, and the biochemical interactions they have with neighboring plants. Here are key considerations and ideal plant partners.
Lupines are leguminous plants that form a symbiotic relationship with Rhizobia bacteria in their root nodules. This process allows them to convert atmospheric nitrogen into a form usable by plants, enriching the soil. This makes them excellent companions for plants that are heavy nitrogen feeders. Ideal companions in this category include members of the Brassica family, such as cabbage, broccoli, and kale, which benefit from the readily available nutrient boost for their leafy growth. Similarly, leafy greens like spinach and lettuce will thrive when planted near nitrogen-fixing lupines.
With their tall, spiky flower racemes, lupines create a strong vertical element in the garden. This structure can be used to provide light shade for plants that prefer protection from the intense afternoon sun. Low-growing, partial-shade tolerant plants make excellent underplantings. Consider planting shade-tolerant herbs like cilantro or parsley, or ornamentals like hostas, around the base of lupines. This maximizes garden space and creates a layered, textured garden bed while protecting more sensitive plants from scorching.
Companion planting can enhance pest management through biochemical means. Lupines can attract a variety of beneficial insects, including pollinators like bees and butterflies, as well as predatory insects that feed on common pests. Interplanting lupines with other plants that also attract beneficials creates a powerful ecological guild. Excellent choices include inviting aromatic herbs like rosemary, oregano, and sage, which can help deter aphids and other pests. Flowers such as nasturtiums act as a trap crop for aphids, luring them away from lupines, while also attracting pollinators. The strong scent of alliums (onions, garlic, chives) can help mask the scent of lupines from browsing animals like rabbits and deer.
From a design perspective, lupines offer a bold form and a wide color range (blues, purples, pinks, whites, yellows). Choosing companions that complement their form and extend the season of interest creates a visually cohesive garden. The vertical spikes of lupines pair beautifully with the large, rounded flower heads of alliums or the flat, open umbels of yarrow. To create a stunning display after lupines have finished blooming, pair them with late-summer perennials like Shasta daisies, coneflowers, or rudbeckia, which will fill the space and maintain visual appeal.
It is equally important to note which plants are not good companions. Avoid planting lupines with other heavy feeders that do not fix their own nitrogen, as they may compete for resources before the lupines have fully enriched the soil. Furthermore, while generally beneficial, it is wise to give members of the Ranunculaceae family (like delphiniums) a bit of space to ensure good air circulation and prevent potential foliar diseases in humid climates.
