How to grow caper
Overview
Caper is a sprawling, deciduous shrub grown for its unopened flower buds, which are pickled and used as a culinary condiment. It thrives in hot, dry, sharply drained sites and is highly drought-tolerant once established, but resents cold, wet soil.
Soil Preparation
Caper requires a free-draining, alkaline to neutral soil with a pH of 7.0–8.5. Amend heavy clay with coarse sand, grit, or crushed limestone to improve drainage. Avoid rich, moisture-retentive soils — caper performs best in lean, rocky, or sandy substrates. If planting in a pot, use a cactus or succulent mix with added perlite.
Growing Guide
Plant caper in full sun in a position with excellent drainage, ideally on a slope or in a raised bed with gravel or crushed rock mulch. Space plants 1–1.5 m apart. Dig a generous hole and backfill with a mix of native soil and coarse sand or grit; avoid any rich organic matter. Water in well after planting, then reduce to once every 2–3 weeks until established. Do not overwater — caper roots rot easily in damp soil.
Sowing
Caper is most commonly grown from seed, but germination is slow and erratic. Sow fresh seed 1 cm deep in a well-draining seed mix, keep at 20–25°C, and expect germination over 4–8 weeks. Scarify or soak seeds in warm water for 24 hours before sowing to improve success. Direct sowing is possible in warm climates but transplanting is more reliable.
Care
Feed caper sparingly with a low-nitrogen fertiliser (e.g., 0–10–10) in early spring and again after the main harvest. Prune lightly after fruiting to shape the plant and remove old, unproductive wood; caper responds well to a hard renewal prune every 3–4 years. Keep the soil surface free of weeds and mulch with gravel or pebbles to reflect heat and suppress competition.
Companion Planting
Caper grows well with other Mediterranean herbs such as rosemary, thyme, lavender, and sage, which share its need for sharp drainage and low water. Avoid planting near moisture-loving vegetables like lettuce or brassicas, which will keep the soil too wet. Also avoid heavy feeders like tomatoes that encourage lush growth and reduce bud set.
Common Pests & Risks
Caper is generally pest-free in Australian gardens but may occasionally attract scale insects on stems and leaves, which can be controlled with horticultural oil. Caterpillars of the caper white butterfly (Belenois java) may defoliate plants; hand-pick or use Bacillus thuringiensis (Bt) if severe. Avoid broad-spectrum sprays that harm beneficial insects.
Harvesting
Harvest caper buds when they are still tight and small, about the size of a pea, before they begin to open. Pick in the early morning after dew has dried, and process within a few hours. Buds can be harvested continuously from late spring through autumn as the plant produces flushes of new growth.
In the Kitchen
Caper buds are pickled in brine or vinegar after a brief salt cure to develop their characteristic tangy, salty flavour. Use them whole in pasta, salads, sauces, and on pizzas. Larger buds can be stuffed with herbs or cheese; the leaves are also edible and can be pickled or used fresh in salads.
Troubleshooting
Yellow leaves: overwatering or poor drainage — reduce water and improve soil aeration. No buds: too much nitrogen or shade — move to full sun and stop feeding. Stunted growth: cold damage or frost — protect with fleece in winter. Leaf drop: waterlogged roots — check drainage and repot if necessary. White caterpillars: caper white butterfly — hand-pick or use Bt spray.