Arabian num-num Care (Carissa spinarum)

This sun-tolerant shrub thrives in bright, warm positions with some protection from extreme heat.

• Provide 6–8 hours of direct sun daily; morning sun with light afternoon shade reduces leaf scorch in hot climates.
• Arabian num-num tolerates partial shade, but flowering and fruiting decline if it receives less than about 4 hours of direct light.
• In very hot summers, use filtered light or dappled shade during the harshest midday sun, especially for young or newly transplanted plants.

This drought-tolerant shrub prefers deep, infrequent watering once established.

• Outdoors in well-drained soil, water only when the top 4–6 cm feels dry, applying a slow, deep soak rather than light splashes.
• Reduce watering in cool seasons, but never allow the root zone to stay waterlogged; sandy or gritty soil helps prevent standing water.
• Signs of overwatering include yellowing leaves and soft stems, while dull, curling leaves and rapid leaf drop suggest the plant is too dry.

This species prefers warm, frost-free conditions but tolerates a fairly wide temperature range once established.

• Ideal growth occurs around 68–86°F (20–30°C), with best flowering and fruiting in consistently warm climates.
• Plants can survive brief drops to about 28–30°F (-2 to -1°C), but foliage damage is likely and young plants are more vulnerable.
• Protect from hard frost and cold winds in winter and from extreme heat above 100°F (38°C) by using mulch and light afternoon shade where possible.

Carissa spinarum handles a wide humidity range and rarely needs special humidity management indoors.

• Target 30–60% humidity, similar to most heated or air‑conditioned homes, when caring for Arabian num-num.
• Expect little stress from dry air; leaf edge browning usually points to inconsistent watering or root issues rather than humidity.
• If air is extremely dry (<25%), place the pot on a pebble tray with water below the pot base to limit tip scorch.

Carissa spinarum prefers sharply drained, sandy to loamy soil that dries moderately between waterings.

• Use a mix of roughly 50–60% cactus potting mix, 20–30% coarse sand, and 10–20% fine bark or perlite for strong aeration.
• Aim for slightly acidic to neutral pH, around 6.0–7.2, avoiding strongly alkaline substrates that may lock up micronutrients.
• Ensure water runs through freely within seconds; add more sand or perlite if water lingers on the surface or the pot feels heavy for long.
• Avoid dense clay, peat-heavy mixes that stay wet, or compacted ground, which raise the risk of root rot and weak growth.

This species is well suited to container growing for patios, balconies, and small gardens.

• Choose a deep, heavy pot that resists tipping, as woody branches and fruit can make the shrub top-heavy in wind.
• Select a mineral-rich, fast-draining container mix so roots anchor firmly and the plant tolerates brief dry spells without collapse.
• Leave 3–5 cm between root ball and pot wall to reduce waterlogging pockets and support even root exploration through the substrate.

Carissa spinarum grows in poor soils but benefits from light feeding in containers or lean garden sites.

• Apply a balanced slow-release fertilizer (such as 10-10-10) at half strength once in early spring and again midsummer.
• For Arabian num-num in pots, supplement with diluted liquid feed (1/4–1/2 strength) every 4–6 weeks during active growth.
• Use a thin layer of compost around the root zone instead of heavy chemical feeding in the ground.
• Stop fertilizing in late summer so new growth hardens before winter, and avoid feeding during winter dormancy.

Pruning Carissa spinarum helps control size, encourage dense branching, and remove unsafe thorny growth.

• Carry out main pruning in late winter or very early spring before vigorous new growth begins.
• Cut out dead, diseased, crossing, or inward-growing branches with clean, sharp bypass pruners or loppers.
• Shorten overly long shoots to maintain a compact, rounded form and improve light penetration into the canopy.
• Avoid cutting back into very old, bare wood; focus on younger stems to sustain flowering and foliage.

This species is more often grown in the ground, but container plants and young hedges sometimes need moving.

• Transplant or shift to a larger pot in late winter or early spring, just before active growth starts.
• Look for roots circling the pot, water running straight through, or slowed growth as signs it has outgrown its container.
• Disturb roots minimally; tease outer roots gently, set at the same depth, and water thoroughly to settle soil and limit stress.
• For established shrubs, move only when necessary, trimming the canopy lightly and keeping the root ball as intact as possible.

Carissa spinarum is commonly propagated from semi-hardwood cuttings or seeds under warm conditions.

• Take semi-hardwood cuttings in late summer, 8–12 cm long, from healthy, non-flowering shoots.
• Remove lower leaves, dip the base in rooting hormone, and place cuttings in a well-drained mix kept at 70–75°F with high humidity.
• For seeds, sow fresh, cleaned seed in a sandy mix, barely covered, and maintain steady warmth for slow, uneven germination.
• Provide bright, indirect light and avoid waterlogging until roots are well formed and new growth appears.

Mature plants are fairly drought-tolerant but can be damaged by hard freezes, especially in exposed sites.

• In regions below about 25°F, grow Carissa spinarum in containers so they can be moved to a bright, frost-free space.
• Mulch the root zone with 5–8 cm of organic material in late fall to moderate soil temperature.
• In marginal climates, use a breathable frost cloth on very cold nights, removing it once temperatures rise.