Lavender Grevillea (Grevillea lavandulacea) is an evergreen shrub native to southeastern Australia. It is valued for its silvery, lavender-like foliage, which provides fine texture and soft color contrast. Its most distinctive feature is the abundance of bright red or pink “spider-like” flowers that appear profusely throughout late winter and spring. These blossoms attract nectar-feeding birds, making it a popular choice for wildlife gardens. Once established, its natural drought tolerance makes it a resilient, low-maintenance plant.
Selecting the Site and Preparing the Soil
Choosing the right location is key for success. The plant requires full sun, ideally six to eight hours of direct sunlight daily, though it can tolerate some afternoon shade. Adequate drainage is non-negotiable, as waterlogged conditions quickly lead to fatal root rot. Grevilleas thrive in poor, gritty, or sandy soils that mimic their natural habitat.
The soil pH should be slightly acidic to neutral. If your garden has heavy clay soil, avoid planting directly into it or significantly improve the area first. For clay, incorporate coarse material like gypsum or coarse sand, or create a raised garden bed to ensure rapid drainage. The plant’s survival depends on preventing its roots from sitting in saturated soil.
The Planting Process and Initial Care
Before planting, thoroughly saturate the root ball. Dig a planting hole that is twice as wide as the root ball but only as deep as the container. This encourages the roots to spread outward into the surrounding soil.
Position the plant so the top of the root ball is level with, or slightly above, the surrounding soil grade to prevent water accumulation. Backfill the hole with the excavated soil, gently firming it around the roots to remove air pockets. Immediately water the area deeply to settle the soil. Apply a layer of low-lying organic mulch, such as pine bark or gravel, around the plant, keeping it several inches away from the main stem to prevent stem rot.
Essential Routine Maintenance
For the first six to eight weeks, water the Grevillea deeply two to three times per week, allowing the topsoil to dry out between applications. After this establishment phase, the plant is drought-tolerant and requires only occasional deep watering during extended dry periods. Overwatering established plants must be avoided.
Grevilleas are extremely sensitive to phosphorus, a common component in standard fertilizers. Their specialized root structure is easily damaged by high phosphorus levels. Therefore, only use a fertilizer specifically formulated for Australian native plants (with a phosphorus content of less than 3%), or ideally, apply no fertilizer at all.
Pruning should be performed lightly and regularly to maintain a dense, bushy shape and encourage continuous flowering. The best time to prune is immediately after the main flush of blooms has finished. Use sharp shears to lightly tip-prune the outer growth, removing spent flowers. Never cut back into old, woody stems that lack foliage, as Grevilleas often fail to regrow from this old wood.
Addressing Common Pests and Health Issues
The most frequent health problem is root rot, caused by poorly draining soil or excessive watering. The first sign is often leaves turning brown and the plant appearing wilted, even if the soil is wet. Prevention through proper site selection and watering practices is the only reliable cure, as the condition is difficult to reverse.
Grevilleas are resilient to insect problems, but they can occasionally be affected by pests like scale insects or mealybugs. Sooty mold, a black substance on the leaves, often indicates a scale infestation. Spraying the affected areas with a horticultural oil or insecticidal soap can manage these soft-bodied pests.
Nutrient problems manifest as yellowing foliage. If new growth turns yellow, it may indicate phosphorus toxicity from using the wrong fertilizer. If older leaves begin to yellow, a deficiency may be present, which should be corrected using only low-phosphorus, slow-release native plant food.