Alternanthera brasiliana aka Ruby Leaf

Alternanthera brasiliana thrives in warm temperatures between 20-38°C (68-100°F), with optimal growth occurring in the range of 18-30°C (64-86°F). This tropical plant does not tolerate frost or freezing temperatures and will be damaged or killed by cold exposure. In regions with harsh winters, it should be grown as an annual or brought indoors when temperatures drop below 15°C (59°F).

This tropical plant prefers humid conditions and thrives in environments with moderate to high humidity. Native to moist tropical and subtropical forests, it performs best when humidity is maintained consistently. In dry indoor environments, occasional misting or use of a pebble tray can help increase humidity around the plant, though it adapts reasonably well to average household humidity levels.

Alternanthera brasiliana propagates easily through stem cuttings or seeds. For cuttings, take 4-6 inch stem sections in spring or summer, keep them moist with indirect sunlight until roots develop (typically 2-3 weeks). Seeds germinate readily and can remain dormant in soil for extended periods before sprouting. The plant also self-seeds prolifically in suitable conditions, and even discarded stem pieces can root and establish new plants when in contact with moist soil.

In cultivation, Alternanthera brasiliana typically grows 40-100 cm (1.3-3.3 feet) tall with a spreading, somewhat sprawling growth habit. Most cultivated specimens remain under 1 meter tall, making them ideal for borders and containers. Under optimal wild conditions, plants can reach up to 3 meters, though this is rare in garden settings. The growth rate is fast—cultivars like 'Little Ruby' can grow 40-60 cm in a single year under good conditions.

Alternanthera brasiliana is native to tropical and subtropical regions of Central and South America, with its range extending from northeastern Mexico through Central America to northeastern Argentina. It is particularly prevalent in Brazil (hence the species name), and also native to Peru, Ecuador, Colombia, Venezuela, the Guyanas, Nicaragua, Belize, Guatemala, Trinidad and Tobago, and various Caribbean islands. The plant naturally grows in moist forests, along stream banks, and on ravine slopes at elevations from 200-600 meters.

Several cultivars are widely grown for their distinctive foliage colors. 'Purple Knight' features deep maroon-purple leaves that become more purple in bright light and greener in shade. 'Little Ruby' is prized for deep burgundy foliage and low spreading habit, very popular in Australian gardens. 'Purple Prince' offers similar deep purple coloration, while 'Snow Queen' provides contrasting variegated foliage. Other cultivars include 'Red Marble', 'Gail's Choice', 'Rubiginosa', and 'Royal Tapestry', each selected for unique foliage characteristics.

Prune lightly in early to late spring to maintain compact shape and remove any dead or damaged stems. Regular light pruning encourages bushier, more compact growth and improves air circulation, which helps prevent fungal diseases. Always sterilize pruning tools before use to prevent disease transmission. The plant responds well to pruning and will quickly produce new growth from cut stems.

Common pests include spider mites, whiteflies, mealybugs, and aphids, particularly when plants are stressed or grown indoors. Disease issues include leaf spot, powdery mildew (especially in humid conditions with poor air circulation), stem rot, and leaf wilting. Overwatering is a primary cause of root rot and fungal infections, so ensure good drainage and avoid waterlogged soil. Regular inspection and maintaining good air circulation help prevent most problems.

Yes, Alternanthera brasiliana produces small white flowers arranged in dense, rounded clusters (inflorescences). The flowers are relatively inconspicuous compared to the showy foliage and bloom year-round in suitable tropical and subtropical climates. While flowering, the plant is primarily grown for its vibrant purple, red, or variegated leaves rather than its blooms.

Alternanthera brasiliana thrives outdoors in USDA hardiness zones 9-11, where it can be grown as a perennial. In colder zones, it's best treated as a seasonal annual or brought indoors before the first frost. The plant performs excellently as bedding plant, border edging, or ground cover in frost-free regions. It grows best in full sun to partial shade with consistent moisture and is popular in tropical and subtropical landscaping for its vibrant foliage.

During active growing season (spring through summer), fertilize every 4-6 weeks with high-nitrogen fertilizer and maintain consistent watering. In winter, reduce fertilization frequency to bi-monthly applications and slightly decrease watering as growth slows. In frost-prone areas, bring container plants indoors before temperatures drop below 15°C (59°F) or treat as an annual. Spring is the best time for pruning and propagation activities.

Yes, the leaves of Alternanthera brasiliana are edible when cooked. In various regions, particularly in West Africa and parts of South America, the leaves are harvested from the wild and prepared as a cooked vegetable similar to spinach or other leafy greens. The plant is sometimes cultivated specifically for this purpose in subsistence agriculture. However, it's primarily known as an ornamental plant rather than a food crop in most regions.

Alternanthera brasiliana has extensive traditional medicinal use, particularly in Brazil where it's known as 'penicilina' and 'terramicina.' Traditional preparations treat inflammation, pain, infections, fever, coughs, colds, headaches, and diarrhea. Scientific research has validated several properties including analgesic, anti-inflammatory, antianxiety, anticonvulsant, and antidiabetic effects. The plant contains bioactive flavonoids, phenolic compounds, and sterols. Leaf infusions and root decoctions are the primary preparation methods. However, medical supervision is recommended before using for therapeutic purposes.

The primary use beyond medicinal and minor culinary applications is ornamental. Alternanthera brasiliana is widely cultivated worldwide as a decorative plant valued for its vibrant purple, red, or variegated foliage. It's popular as a bedding plant, border edging, container plant, and ground cover in tropical and subtropical landscapes. Numerous cultivars have been developed specifically for ornamental horticulture, and it's a staple in warm-climate landscaping across Australia, the Americas, and other tropical regions.

Ruby Leaf is a low-maintenance plant that requires minimal attention, making it an excellent choice for beginners.

Ruby Leaf should be watered regularly, allowing the soil to dry out between waterings.

Ruby Leaf 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.

Ruby Leaf requires abundant, bright and direct light. Placing it less than one foot from a window is the best way to make sure the plant receives enough light to survive and thrive. Depending on your region, however, the current weather can affect the placement of the plant in your home. For example, in some areas the sun may be too direct and intense, so it's best to place it farther away from the window. You may also need to adjust your placement according to the season as the sunlight can change intensity over the course of the year. If you live in a region with significant temperature fluctuations, such as a desert, you may need to place the plant a bit farther away from the window to avoid extreme heat or cold. With some care and attention, your Ruby Leaf will be sure to bring you many years of beauty and enjoyment.

The Ruby Leaf should be repotted either when it doubles in size or annually, whichever comes first. Providing new potting soil with all the vital nutrients annually is enough to support the growth of the plant, and thus, there is no need for fertilizer. Remember that plants derive their energy from the sun, not fertilizer.

Ploi's records do not contain confirmed information on the toxicity of this particular plant. In the event of accidental ingestion of plant material with questionable toxicity by you, a family member, or a pet, it is always a good idea to consult a healthcare professional.