Passiflora laurifolia aka Water Lemon

Passiflora laurifolia is a challenging plant to grow successfully, primarily due to its strict tropical requirements. It cannot tolerate any frost and requires consistently warm temperatures between 22-30°C (70-86°F). The plant needs cross-pollination by carpenter bees to produce fruit—without these pollinators, hand pollination is necessary. It thrives best in humid tropical climates with 2,000-3,000mm annual rainfall and struggles in drier or cooler conditions.

Passiflora laurifolia is a vigorous, fast-growing evergreen vine that can reach impressive lengths of 15-18 meters (49-59 feet). The woody stems climb using coiling tendrils that wrap around supporting structures like trees, trellises, or pergolas. When grown with adequate support, space, and tropical conditions, it can quickly cover large areas. The vine spreads significantly and requires sturdy support structures to accommodate its vigorous growth habit.

Passiflora laurifolia requires consistent tropical warmth and cannot tolerate frost. The optimal temperature range is 22-30°C (72-86°F), though it can tolerate extremes from 12-36°C (53-97°F) for short periods. Any exposure to frost will damage or kill the plant. In subtropical regions, it should only be grown in frost-free microclimates or protected with winter shelter.

As a rainforest species, Passiflora laurifolia thrives in high humidity environments. It naturally grows in wet tropical biomes with annual rainfall of 2,000-3,000mm, though it can tolerate 1,000-4,000mm. In drier climates, regular misting and consistent soil moisture help compensate for lower atmospheric humidity. The plant performs best in humid tropical or subtropical conditions with year-round warmth and moisture.

Passiflora laurifolia benefits from regular feeding during the growing season. Apply a balanced fertilizer every 2-4 weeks from spring through autumn, or use a slow-release fertilizer at the start of the growing season. The plant prefers humus-rich soil, so incorporating organic matter like compost or well-rotted manure helps provide nutrients and improve soil structure. Avoid over-fertilizing with nitrogen, which may promote leaf growth at the expense of flowering and fruiting.

Passiflora laurifolia can be propagated by seeds, cuttings, or layering. Germination can be slow, taking up to 12 months. Stem cuttings taken from young shoots root more readily than mature wood—use neutral to slightly acidic compost or sharp sand as the rooting medium. Layering is described as 'very easy' and air layering is also effective for this species.

Passiflora laurifolia produces stunning fragrant flowers that are blue to purplish-blue, measuring up to 75mm (3 inches) wide. The intricate corona filaments display beautiful banding in reddish-purple, blue, violet, and white. A distinctive characteristic is that flowers open only in the afternoon, typically from May through August in seasonal climates. In consistently tropical conditions, flowering may occur year-round. The flowers require cross-pollination by carpenter bees (Xylocopa species) or hand pollination to set fruit.

Passiflora laurifolia requires cross-pollination to produce fruit and relies primarily on large carpenter bees (Xylocopa species) as pollinators. The flowers open only in the afternoon, and a warm, dry atmosphere is essential for proper stigma maturation. If carpenter bees are not present, hand pollination is necessary—transfer pollen from the anthers of one flower to the stigma of another using a small brush. Self-pollination is either not possible or produces very poor results.

Passiflora laurifolia tolerates heavy pruning and can even be cut back to ground level for complete rejuvenation if needed. Regular pruning helps control the vine's vigorous growth and maintain desired size and shape. Prune after fruiting or during the dormant season in cooler climates. Remove dead, damaged, or overcrowded growth to improve air circulation. The genus Passiflora is notably resistant to honey fungus, so disease following pruning cuts is uncommon.

Passiflora laurifolia can only be grown outdoors in tropical and frost-free subtropical regions corresponding to USDA zones 10-12. It thrives in its native range throughout the Caribbean and tropical South America, as well as in introduced tropical locations worldwide. The species is strictly frost-intolerant—any cold exposure will damage or kill it. In temperate climates, it cannot survive outdoors year-round and would require a heated greenhouse or conservatory.

Passiflora laurifolia shows fair resistance to root-knot nematodes, which affect many other passion fruit species. The genus Passiflora is notably resistant to honey fungus. Common passion vine pests include aphids, spider mites, and caterpillars of Heliconius butterflies (whose larvae specifically feed on Passiflora leaves). Fungal diseases can occur in overly wet conditions with poor air circulation. This species is actually valued as rootstock for commercial P. edulis because of its resistance to soil-borne diseases.

The ripe fruit of Passiflora laurifolia is highly edible and considered excellent, earning a 4 out of 5 edibility rating. The aromatic pulp is fragrant, juicy, and 'agreeably subacid'—milder and more perfumed than common passion fruit, without the tartness. It's rich in vitamin C and can be eaten raw by making a hole in the fruit and sucking out the pulp and seeds, or processed into refreshing drinks, ice cream, and sweets. However, the leaves are poisonous and green unripe fruit contains cyanogenic compounds that disappear upon ripening.

Passiflora laurifolia has traditional medicinal uses, rated 2 out of 5 for medicinal value. The leaves and roots contain compounds with tranquilizing properties, including the glycoside passiflorin which has weak narcotic effects. Traditionally, powdered leaves have been used as a vermifuge (to expel intestinal parasites) and root decoctions as anthelmintic treatments. Leaf poultices have been applied to skin conditions. Despite these uses, the leaves are poisonous and should not be consumed without proper preparation and guidance.

Beyond its edible fruit, Passiflora laurifolia has several practical applications. It's commonly used as rootstock for grafting commercial passion fruit (Passiflora edulis) because of its superior resistance to soil-borne diseases. Extracts from the flowers and fruit are used in cosmetics as skin conditioners. The vine is suitable for food forest systems and provides excellent coverage for pergolas, arbors, and fences in tropical gardens. Its nectar-rich flowers also support native pollinator populations.

In its native tropical habitat, Passiflora laurifolia grows continuously year-round without a true dormancy period. In subtropical regions at the edge of its hardiness range (zone 10), growth may slow during cooler winter months, and the plant may need protection from any cold snaps. Watering can be reduced slightly during cooler periods but soil should never dry out completely. In consistently tropical climates, flowering and fruiting occur throughout the year with peak production following seasonal rainfall patterns.

Water Lemon’s native range is S. America - eastern Brazil, Peru, Venezuela, Guyanas to the Caribbean.

Water Lemon should be watered regularly, allowing the soil to dry out between waterings.

Water Lemon loves a well-draining soil. Perlite and vermiculite help with drainage, while coco coir adds organic matter, so a good potting soil mix will have all three. You can improve store-bought soil by adding some perlite to it.

To ensure optimal growth, the Water Lemon prefers bright diffused light for 6-8 hours each day. Insufficient light can result in slow growth and leaf drop, so it's important to find a well-lit location for this plant. Place it near a window, within a distance of 1 meter (3 feet), to enhance its potential for thriving.

Ploi lacks confirmed information on the toxicity of this plant. If you, a relative, or your pet accidentally consume plant material with unknown toxicity, it's best to consult a medical expert.