How to grow spider flower
Overview
Spider flower (Grevillea spp.) is a hardy, evergreen shrub grown for its intricate, spider-like blooms and fine foliage. It provides year-round structure and colour, and is excellent for linking feature plants in the garden. Requires excellent drainage and will not tolerate wet feet.
Varieties
- Robyn Gordon — A compact, ever-blooming red-flowered hybrid (4m if not pruned) ideal for smaller gardens in temperate to subtropical zones.
- Superb — A vigorous large shrub with showy pink-red flower clusters; excellent screening plant for warm climates.
- Poorinda Royal Mantle — A low-growing groundcover with soft grey-green foliage and red toothbrush flowers, suitable for banks and slopes.
- Misty Pink — A medium-sized shrub with masses of soft pink spider flowers over a long period; very heat and drought tolerant.
- Moonlight — A tall shrub (3–5m) with creamy-white flowers; popular in subtropical and tropical gardens for its elegance.
Soil Preparation
Prefers slightly acidic to neutral pH (5.5–7.0). Sandy loam or gravelly soil with perfect drainage is essential. If soil is clay, plant in a raised bed or mound amended with coarse sand and decomposed granite. Avoid adding organic matter that retains water.
Growing Guide
Plant spider flower in full sun in a free-draining sandy or gravelly soil. Space shrubs 1–3 m apart depending on habit. Dig the hole twice as wide as the root ball but no deeper; backfill with native mix. Water in well, then let the soil dry before watering again. In cooler zones, wait until after the last frost before planting. Mulch with gravel or small pebbles, not organic matter that holds moisture.
Sowing
Spider flower is not commonly grown from seed in home gardens because germination is slow and unreliable. Most gardeners buy established plants or take semi-hardwood cuttings in summer. If sowing, nick the seed coat and soak for 24 hours, sow 5 mm deep, and keep at 20–25°C; germination takes 3–6 weeks.
Care
Feed with a low-phosphorus native fertiliser in early spring only. Prune lightly after flowering to maintain shape and encourage dense growth – cut just above a leaf node. Remove spent flower heads to prolong blooming. Do not use high-phosphorus fertilisers or mushroom compost.
Companion Planting
Spider flower pairs beautifully with other dry-loving native shrubs like Westringia fruticosa, Eremophila nivea, and Correa alba. Avoid planting near moisture-loving plants such as ferns or clivia, which demand regular watering that would harm Grevillea.
Common Pests & Risks
Root rot (Phytophthora) is the most serious issue, caused by poorly drained soil – avoid overwatering and improve drainage. Scale insects and spider mites may attack stressed plants; control with horticultural oil. Grevillea can also host leaf-spotting fungi in humid conditions; prune for airflow.
Harvesting
For cut flowers, pick stems when the first flowers open in the cluster – they will continue to open in the vase. Harvest from mid-spring through summer. Use sharp secateurs and place immediately into water; Grevillea flowers last up to two weeks.
Troubleshooting
Yellowing leaves with dark veins: often iron chlorosis due to high soil pH or phosphorus toxicity; apply chelated iron and stop using high-P fertiliser. Brown leaf tips: caused by dry air or salt build-up; flush soil with rainwater and increase humidity. Sudden wilting despite moist soil: likely root rot from overwatering; reduce watering and improve drainage – if severe, replace plant. Sparse growth and few flowers: usually lack of sun or too much nitrogen; move to full sun and switch to low-N native fertiliser. Sticky leaves with sooty mould: scale insect infestation; treat with neem oil and improve airflow.