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Alternanthera Red Knight
Alternanthera dentata 'Red Knight'
shrubAlternanthera Red Knight is a vibrant ornamental foliage plant prized for its deep burgundy-red leaves with purple undersides. This tender perennial shrub is grown as an annual in most climates and adds dramatic color to garden beds, borders, and containers. It maintains a compact, bushy form and is popular in both landscape design and aquascaping.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 10-11; grown as annual in zones 4-9
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Growth Stages
Seedling
2-3 weeksTiny seedlings emerge with small oval leaves showing early red tinges. Very delicate and vulnerable to damping off.
Keep under grow lights, maintain 70-75°F, ensure high humidity, water gently from below, provide air circulation
Vegetative Growth
3-5 weeksPlant develops bushy shape with increasing leaf production; red coloration becomes more pronounced with improved light and maturity.
Pinch growing tips every 2-3 weeks to encourage bushiness, feed with balanced fertilizer every 2 weeks, ensure full sun exposure
Established Growth
Ongoing through growing seasonFull bushy form achieved with dense foliage; deep burgundy-red leaves are vibrant and glossy, purple undersides visible on mature leaves.
Deadhead any small inconspicuous flowers to encourage foliage production, fertilize weekly with diluted liquid fertilizer, maintain consistent moisture
Peak Color
Mid-summer through fallPlant reaches maximum color intensity and ornamental appeal with rich deep red foliage throughout.
Maintain full sun, continue regular feeding, pinch as needed to maintain shape, monitor for pests in warm weather
Senescence/Winter Dormancy
Fall through winterIn cool climates, plant declines as temperatures drop below 50°F; leaves may lose color or plant may die back completely.
Bring containers indoors in zones 4-9, reduce watering, stop fertilizing, maintain 55-65°F indoors, or take cuttings for propagation
Common Pests
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Increase humidity, mist regularly, spray with neem oil or insecticidal soap, improve air circulation
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Remove with alcohol-soaked cotton swab, spray with insecticidal soap or neem oil, isolate infested plants
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Hand-pick or scrape off, spray with horticultural oil, treat with neem oil, prune heavily infested stems
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Yellow sticky traps, spray with insecticidal soap, increase air circulation, neem oil applications
Uses
Garden and Landscape Design
HouseholdAlternanthera Red Knight serves as a striking foliage accent in flower beds, borders, container gardens, and mixed plantings. Its intense red coloration provides excellent contrast to green or silver-foliaged plants and brightens shaded areas of the garden. [source]
Container and Patio Gardening
HouseholdIts compact growth habit makes it ideal for pots, hanging baskets, window boxes, and mixed containers. Red Knight works beautifully as a thriller, filler, or spiller in container design schemes. [source]
Aquascaping and Water Gardens
HouseholdAlternanthera varieties are popular aquatic stem plants used as background and mid-ground plants in freshwater aquariums. The red coloration requires high light and nutrients, making it prized by aquascapers. [source]
Indoor Decorative Houseplant
HouseholdIn colder climates, Red Knight can be grown indoors on bright windowsills or under grow lights. Its compact form and colorful foliage make it an attractive indoor accent plant. [source]
Pollinator Plantings
WildlifeWhile grown primarily for foliage, small flowers attract beneficial insects including bees and small butterflies. It provides shelter and food sources for garden insects. [source]
Harvest Tips
This is an ornamental foliage plant, not harvested for food. Pinch or prune stems regularly (every 2-3 weeks) to maintain compact bushy shape and encourage fuller color development. Take 3-4 inch stem cuttings anytime during growing season for propagation; cuttings root easily in water or moist soil within 1-2 weeks.
Fun Facts
- 🌱 Alternanthera Red Knight is sometimes called 'Joseph's Coat' due to its rich multicolored foliage that resembles the biblical coat of many colors; the purple-red coloration is more intense when grown in cooler temperatures and bright light.
- 🌱 This plant is easier to propagate from cuttings than from seed and will root in water within 1-2 weeks, making it simple to create new plants or overwinter specimens indoors.
- 🌱 In aquariums, Alternanthera plants can grow emersed (above water) or submersed (underwater), and the Red Knight variety is particularly prized because its vibrant red color intensifies under high-intensity aquarium lighting.
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