Justicia gendarussa aka Willow Leaved Justicia

Justicia gendarussa prefers consistently moist soil and should be watered regularly to maintain even moisture levels. Water the plant when the top inch of soil begins to dry out, typically 2-3 times per week during the growing season. Avoid allowing the soil to dry completely between waterings, but ensure proper drainage to prevent waterlogging and root rot. Reduce watering frequency during winter dormancy, keeping the soil just barely moist.

Justicia gendarussa is adaptable to various soil types including light sandy, medium loamy, and heavy clay soils. For best results, use well-draining soil rich in organic matter with a slightly acidic to neutral pH (6.0-7.0). A quality potting mix amended with compost or aged manure works well for container cultivation. Good drainage is essential despite the plant's preference for consistent moisture, as waterlogged soil can lead to root rot.

Justicia gendarussa thrives in warm temperatures between 65-85°F (18-29°C) and is not frost-tolerant. This tropical plant requires year-round warmth and will suffer damage if exposed to temperatures below 40°F (4°C). For propagation, maintain temperatures around 70-75°F (21-24°C). In cooler climates (outside USDA zones 10-11), grow the plant in a warm greenhouse or bring containers indoors during winter months.

Justicia gendarussa appreciates moderate to high humidity levels typical of its native tropical forest habitat. While the plant can tolerate average household humidity, it performs best with humidity levels above 50-60%. In dry indoor environments, increase humidity by misting the foliage regularly, placing the pot on a pebble tray with water, or using a humidifier nearby. Outdoor plants in suitable climates generally receive adequate humidity naturally.

Feed Justicia gendarussa with a balanced, water-soluble fertilizer (10-10-10 N-P-K ratio) every 4-6 weeks during the active growing season (spring through fall). Apply fertilizer at half the recommended strength to avoid burning the roots. Alternatively, top-dress monthly with organic compost such as vermicompost to provide steady nutrients and enhance soil quality. Reduce or suspend fertilization during winter dormancy when the plant's growth naturally slows.

Justicia gendarussa propagates readily from stem cuttings or seeds. For cuttings, take 6-8 inch segments from healthy stems in spring or early summer, remove lower leaves leaving 2-3 at the top, and optionally dip in rooting hormone. Insert cuttings 1 inch deep in moist potting mix, maintain 70-75°F temperatures, and keep in indirect light until roots establish in 3-4 weeks. Seeds can be sown in containers, but viability is short-lived, so use fresh seed and maintain warm, moist conditions for germination.

Justicia gendarussa produces attractive tubular flowers from late spring through early fall, with potential for year-round blooming in consistently warm tropical climates. The flowers appear in terminal or axillary spikes (racemes) 4-12 cm long, with individual blooms measuring 1.6-2 cm. Flowers are typically white to pale pink or violet, adorned with distinctive purple streaks and spots inside. The blooms attract pollinators including bees and butterflies, adding ornamental value to the already graceful willow-like foliage.

The primary cultivated variety of Justicia gendarussa is 'Variegata' (Variegated Willow-leaved Justicia), which features attractive cream or white variegation on the foliage. This cultivar grows slightly more compact than the species, typically reaching 0.5-0.6 meters in height. The variegated form is popular as an ornamental for its striking foliage contrast while maintaining the same care requirements and flowering characteristics as the standard green-leaved species.

Justicia gendarussa can be grown outdoors year-round only in USDA hardiness zones 10-11, where temperatures remain above 30-40°F (minimum). This tropical shrub thrives outdoors in warm, frost-free climates similar to its native range across tropical Asia. In cooler regions, the plant is not hardy and will suffer damage from frost. Gardeners in zones 9 and below should grow it as a container plant that can be moved indoors during winter, or cultivate it in a warm greenhouse year-round.

Prune Justicia gendarussa in early spring before new growth begins to maintain shape, encourage bushier growth, and remove any dead or damaged stems. Cut back leggy stems by one-third to one-half their length using clean, sharp pruning shears. Pinch back growing tips during the growing season to promote branching and a fuller appearance. Remove spent flower spikes to encourage continued blooming and maintain a tidy appearance throughout the flowering season.

Repot Justicia gendarussa every 2-3 years in spring when the plant becomes root-bound or when roots begin growing through drainage holes. Choose a container 2-4 inches larger in diameter than the current pot with adequate drainage holes. Use fresh, well-draining potting mix enriched with organic matter. After repotting, water thoroughly and place in a shaded location for 1-2 weeks to reduce transplant shock before gradually returning to normal light conditions.

Justicia gendarussa typically reaches 1-1.5 meters (3-5 feet) in height at maturity, though some specimens may grow up to 2 meters in ideal conditions. The plant exhibits a moderate growth rate, developing into a highly branched, upright shrub with a bushy, rounded form. The variegated cultivar 'Variegata' tends to be more compact at 0.5-0.6 meters tall. Growth is most vigorous during warm months with adequate moisture and nutrients, slowing or stopping during cooler winter periods in seasonal climates.

Justicia gendarussa is generally resistant to serious pests and diseases when grown in appropriate conditions. However, it may occasionally be affected by common garden pests such as aphids, whiteflies, or spider mites, particularly when grown indoors or in stressed conditions. Overwatering or poor drainage can lead to root rot and fungal issues. Maintain good air circulation, avoid overhead watering, and ensure proper drainage to prevent disease. Treat pest infestations promptly with insecticidal soap or neem oil applications.

Justicia gendarussa has extensive traditional medicinal applications across its native range in Ayurveda and Southeast Asian folk medicine. The leaves and young shoots possess antispasmodic, antiperiodic, cardiotonic, and febrifuge properties, used to treat headaches, paralysis, lumbago, fevers, coughs, asthma, and eczema. The root demonstrates anodyne, diaphoretic, and diuretic effects for treating rheumatism and fevers. Modern research has confirmed antimicrobial, anti-inflammatory, antioxidant, and hepatoprotective activities. However, medicinal use should only be undertaken under qualified supervision.

Beyond its medicinal applications, Justicia gendarussa has several practical uses. The dried leaves serve as a natural insect repellent for protecting stored clothing from moths and other pests. It's also employed in agroforestry systems as living fences to delineate property boundaries. The flowers attract beneficial pollinators including bees and butterflies, making it useful in pollinator gardens.

Caring for Willow Leaved Justicia is a breeze, as it is highly adaptable and forgiving to minor neglect.

Willow Leaved Justicia’s native range is E. Asia - India to Burma.

To ensure optimal growth, the Willow Leaved Justicia prefers bright indirect 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.

There is no verified data on the toxicity of this plant in the records of Ploi. If any person, including yourself, a family member, or a pet, consume plant material with an uncertain toxicity level, it is advisable to seek the advice of a healthcare expert.

During the cold period, it is common for Willow Leaved Justicia to go dormant, resulting in a slowdown of growth. To accommodate this, waterings should be spaced out more.