Rhopalostylis sapida aka Nikau Palm

Rhopalostylis sapida (nīkau) is endemic to New Zealand and is the only palm species native to mainland New Zealand. Its natural range includes coastal and lowland forest throughout the North Island, and on the South Island as far south as Ōkārito in the west and Banks Peninsula in the east. It also occurs on Chatham Island and Pitt Island, where at 44°18'S latitude it holds the record as the world's most southerly-growing palm.

Rhopalostylis sapida is a slow-growing palm that reaches 8-15 metres in height with a spread of 2.5-4 metres when mature. It takes 20-50 years to reach ultimate height, and flowering typically doesn't begin until the tree is around 30 years old. The trunk is stout and green with grey-green leaf scars, topped by a distinctive smooth, bulging crownshaft up to 1 metre long. The crown consists of feathery fronds 1.2-3 metres long forming an upright shuttlecock shape.

Rhopalostylis sapida prefers fertile, well-drained soil that remains moist. It thrives in loamy or sandy soil types and is adaptable to a wide pH range, tolerating acid, neutral, or alkaline conditions. Clay or sandy soils are also tolerated with moderate watering. For container growing, use a rich, humus-based potting mix that drains well while retaining moisture. Adding organic matter helps replicate its natural forest floor environment.

Rhopalostylis sapida thrives in humid, mild environments and originates from New Zealand's coastal and lowland forests where humidity is naturally high. When grown indoors or in a greenhouse, maintain moderate to high humidity levels. In dry indoor conditions, regular misting or placing the pot on a pebble tray with water can help. The species particularly benefits from sheltered positions that retain humidity and protect from drying winds.

Rhopalostylis sapida prefers a minimum temperature of 10-15°C and is rated H2 (tender) by the RHS, meaning it requires cool or frost-free greenhouse conditions in the UK. However, mature trees can tolerate brief periods down to -4°C (25°F). In USDA zones 9a-11b, it can be grown outdoors year-round with winter protection. Young plants are more frost-sensitive than established specimens, so gradual hardening off is recommended in borderline climates.

Feed Rhopalostylis sapida with a balanced slow-release palm fertilizer during the growing season (spring through autumn). Apply fertilizer sparingly as the species is a slow grower and doesn't require heavy feeding. In containers, monthly applications of a diluted liquid fertilizer can supplement slow-release granules. Avoid over-fertilizing, which can damage roots. Ensure the soil is moist before applying fertilizer to prevent root burn.

Rhopalostylis sapida is propagated exclusively by seed, as it produces a single trunk with no suckers. Collect ripe red fruits and soak them in water for a few days, then lightly scrub to remove the flesh. Place cleaned seeds in sealed plastic bags in half-shade until germination begins. Plant germinating seeds in deep, narrow pots to accommodate the developing taproot. Germination typically occurs within 2-3 months with fresh seed. Handle seedlings carefully—avoid disturbing the roots as much as possible, as the species dislikes being transplanted once established.

Rhopalostylis sapida produces multibranched inflorescences 20-40cm long with tightly packed lilac to pink flowers from November to April (Southern Hemisphere summer). Flowering typically doesn't begin until the tree is around 30 years old. Each flower branch contains small unisexual flowers arranged in groups of three: a central female flower flanked by two male flowers. The resulting elliptic red fruits take nearly a full year to ripen, from February to November, and are an important food source for native birds like kererū.

Rhopalostylis sapida is pollinated by insects attracted to the nectar and pollen produced by its lilac-pink flowers. After pollination, the resulting bright red fruits are dispersed by native New Zealand birds, particularly the kererū (native wood pigeon) and kākā. This ecological relationship links coastal forest remnants and contributes to forest regeneration. The fruits are a favored food source for these birds, who spread the seeds through the forest.

Rhopalostylis sapida can be grown outdoors in USDA zones 9a-11b and mild, humid, frost-free gardens. In the UK it requires a cool or frost-free greenhouse except in the mildest coastal areas. Choose a sheltered location with protection from strong winds and direct sun. The species grows faster and stronger when surrounded by other evergreen plants that provide shelter. Mature trees tolerate brief cold snaps to -4°C, but young plants need frost protection. In marginal climates, container growing allows moving plants to shelter in winter.

Rhopalostylis sapida requires no regular pruning. Dead fronds naturally fall away from the trunk, leaving distinctive grey-green leaf scars. Only remove completely brown, dead fronds if desired for aesthetic reasons—never cut green or partially green fronds as this depletes the palm's energy reserves. The crownshaft is self-cleaning and should never be trimmed. Avoid any cutting near the single growing point at the top of the trunk, as damage here will kill the entire tree.

Rhopalostylis sapida dislikes being moved or having its roots disturbed, particularly when mature. Repot only when absolutely necessary, ideally when the plant is young and actively growing. Use deep, narrow pots to accommodate the developing taproot. When repotting, handle the root system gently and avoid breaking the taproot. Increase pot size gradually rather than moving to an oversized container. The species is reportedly easier to transplant when young, so establish it in its final position as early as possible if growing outdoors.

Rhopalostylis sapida is generally disease-free but can be affected by common palm pests including scale insects, mealy bugs, and glasshouse red spider mite, particularly when grown under glass. Inspect regularly for these pests, especially on the undersides of fronds and around the crownshaft. Treat infestations promptly with appropriate horticultural oils or insecticidal soap. Good air circulation and avoiding overwatering help prevent most problems. In outdoor settings in suitable climates, pest issues are less common.

Plants from different regions of New Zealand show notable variations. Specimens from the South Island and offshore islands of the North Island have larger, more gracefully arching fronds and are popular in cultivation. The Chatham Islands form is particularly distinctive, with a unique juvenile form, larger fruits, and a thicker covering of fine hairs (indumentum) on the fronds. The closely related Rhopalostylis baueri (Norfolk Island nikau) differs mainly in having globose to oval fruits and broader leaflets in most populations.

In winter, reduce watering as growth slows, allowing the soil to dry slightly more between waterings while never letting it become completely dry. Protect from frost—move container plants to a cool greenhouse or sheltered position before temperatures drop below 10°C. Mature outdoor specimens in mild areas may tolerate brief cold snaps to -4°C but benefit from fleece wrapping during severe cold. Avoid feeding during winter dormancy. Ensure good air circulation to prevent fungal issues in enclosed spaces.

Several parts of Rhopalostylis sapida are edible and were traditionally used as food by Māori. The bases of inner leaves and young flower clusters can be eaten raw or cooked—the immature flower is sometimes compared to cauliflower. Immature green berries are also edible. The heart of developing leaves, called rito, is a traditional delicacy with a subtle, savoury flavour (the species name 'sapida' means 'savoury'). However, harvesting rito kills the entire tree, so it was only rarely consumed and is now discouraged for conservation.

In traditional Māori rongoā (medicine), the heart of the nikau palm (rito) was used as a laxative, considered especially important for use before childbirth. The pith was believed to help relax pelvic ligaments in pregnant women, potentially easing delivery. These uses are documented in traditional knowledge but are not practiced widely today, partly because harvesting the heart kills the tree. Modern use for these purposes is not recommended.

Rhopalostylis sapida was highly valued by Māori for practical purposes. The fibrous leaves were woven into kete (baskets), floor mats, hats, and waterproof thatch for buildings without any need for processing. Leaves were also wrapped around food for cooking and woven into leggings for protection in dense undergrowth. The outer portion of the trunk was fashioned into storage containers and pots, while tough leaf bases became scoops and vessels. The hard berries were traditionally strung into necklaces. The species is considered a taonga (treasure) with cultural and spiritual significance.