To successfully choose companion plants for Grevillea, one must first understand its origins. Most cultivated Grevilleas hail from Australia, thriving in well-drained, often sandy or gravelly, acidic to neutral soils. They are typically sun-loving plants that are highly drought-tolerant once established. A key consideration is their sensitivity to phosphorus; many Australian natives, including Grevillea, have evolved to be highly efficient at absorbing this nutrient and can suffer from toxicity when exposed to high-phosphate fertilizers commonly used for other plants. Therefore, the primary rule for companionship is selecting plants that share these cultural requirements: full sun, excellent drainage, and a low-phosphorus diet.
The most logical companions are plants from a similar ecological niche. Other Australian natives create a cohesive, low-maintenance landscape that thrives under the same conditions. Excellent choices include:
Low-Growing Shrubs & Groundcovers: Prostrate forms of Leptospermum (Tea Tree) or Baeckea provide excellent weed-suppressing groundcover that won't compete aggressively with the Grevillea's roots. Westringia (Coastal Rosemary) offers fine, grey-green foliage that contrasts beautifully with the often needle-like leaves of Grevillea.
Architectural Accents: Grasses like Lomandra species provide stunning textural contrast with their strappy, flowing foliage. The bold structural forms of Dianella (Flax Lily) also work well, offering both foliage interest and small, delicate flowers.
Given the similar climate profiles of Australia and regions like California, many plants from Mediterranean climates are superb companions. These plants are adapted to summer drought, full sun, and poor, well-drained soils.
Drought-Tolerant Perennials: Lavender (Lavandula), Rosemary (Rosmarinus officinalis), and Sage (Salvia) are outstanding choices. Their grey, green, and silver foliage complements Grevillea's leaves, and their flowering periods often overlap, providing a long season of nectar for pollinators. California natives like Ceanothus (California Lilac) or Arctostaphylos (Manzanita) make excellent larger shrub companions.
For a truly modern and water-wise garden bed, incorporating succulents can be highly effective. Their bold forms and unique textures create a striking visual partnership with Grevillea.
Color and Form: The silvery-blue rosettes of Agave parryi or the vertical lines of Aloe species provide dramatic architectural interest. Low-growing sedums or sprawling Senecio serpens (Blue Chalksticks) can serve as a living mulch, covering the soil surface with cool-colored foliage that reduces water loss and echoes the blue-grey tones found in some Grevillea varieties.
It is crucial to avoid plants with conflicting needs. Do not companion plant with heavy feeders or plants that require rich, moist soil, such as traditional garden annuals, most vegetables, or plants like Roses and Hydrangeas. These will require frequent watering and fertilization, which will inevitably lead to root rot and phosphorus toxicity for the Grevillea. Similarly, avoid large trees or aggressive shrubs with dense, shallow root systems that will outcompete the Grevillea for water and nutrients.
