How to Grow Purple Stem Okinawan Amaranth

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Purple Stem Okinawan Amaranth

Amaranthus gangeticus

vegetable

A tropical leafy green vegetable with distinctive purple-red stems and dark green leaves, prized in Asian cuisines for its nutritious foliage and edible stems. The plant grows upright and bushy, reaching 2-3 feet tall with tender leaves that can be harvested continuously. Rich in vitamins, minerals, and antioxidants, it thrives in warm conditions and produces prolifically throughout the growing season.

Looking for a specific variety?

Okinawan Amaranth Chinese Amaranth Green Amaranth Red Amaranth Tampala Amaranth Love-Lies-Bleeding Amaranth

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Example Purple Stem Okinawan Amaranth timeline · Pittsburgh, PA (Zone 6b)

Plant Purple Stem Okinawan Amaranth
Around Apr 17

Near Pittsburgh's average last spring frost.
Tend & protect
Late spring–summer

Watering, feeding, and pest-watch reminders.
Harvest Purple Stem Okinawan Amaranth
Around May 17

≈ 30 days after planting

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Growing Conditions

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Sun: Full sun, 6-8 hours daily minimum; prefers warm, bright locations

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Water: Keep soil consistently moist but not waterlogged; water deeply 2-3 times per week depending on temperature and rainfall. Amaranth prefers warm soil; avoid cold water and ensure good drainage to prevent root rot.

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Spacing: 12-18 inches

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Days to maturity: 30-50 days to first harvest (continuous harvesting thereafter)

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Planting depth: Surface sow or ¼ inch deep; seeds need light to germinate

Soil

Type: Well-draining, fertile loamy soil

pH: 6.0-7.0

Amendments:

Compost or well-rotted manure Balanced organic fertilizer Perlite or sand for drainage improvement

Growing Zones

Find your zone →

Thrives in zones 10-11; can be grown as an annual in zones 8-9 with season extension or in containers

10a 10b 11a 11b

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Growth Stages

Germination & Seedling

2-3 weeks

Tiny seedlings emerge with cotyledons in 7-14 days. Initial growth is slow; leaves are pale green and delicate.

Keep soil warm (70-80°F) and consistently moist. Provide bright light to prevent leggy growth. Thin seedlings to appropriate spacing once first true leaves appear.

Vegetative Growth

2-3 weeks

Plant develops several sets of true leaves with increasingly visible purple-red stems. Bushy growth pattern emerges; plant reaches 6-12 inches tall.

Maintain consistent moisture and warmth. Apply balanced fertilizer every 2-3 weeks. Pinch off terminal buds to encourage branching and bushier habit.

Leaf Development & Early Harvesting

3-4 weeks

Plant becomes fully bushy with abundant dark green leaves on purple stems. Ready for first harvest at 8-12 inches height.

Begin harvesting outer leaves and stem tips; this encourages continued branching. Water deeply and fertilize bi-weekly. Monitor for pests in warm weather.

Peak Production

4-8 weeks or until first frost/season end

Mature plant stands 2-3 feet tall with prolific leaf and stem production. Full purple coloration of stems is most vibrant. Plant may begin to flower if not harvested regularly.

Harvest regularly (every 5-7 days) to prevent flowering and keep plant productive. Continue regular watering and feeding. Pinch off flower buds if they appear.

Decline & Season End

Variable; until frost or end of growing season

Plant begins to flower and seed if not continuously harvested. Growth slows in cooler temperatures or with reduced daylight.

Allow some plants to flower if saving seeds; otherwise continue harvesting or remove plants. In tropical zones, can be replanted for successive harvests.

Companion Planting

Plan your garden →

Plant with:

Basil Eggplant Cucumber Dill Tomato Squash Marigold Bean

Avoid planting near:

Spinach Beet Chard Fennel Walnut trees

Common Pests

Hand-pick larvae; use netting to exclude moths; apply Bacillus thuringiensis (Bt) spray for heavy infestations; encourage beneficial wasps
Use floating row covers on young plants; apply neem oil or kaolin clay spray; increase humidity to deter beetles
Strong water spray to dislodge; use yellow sticky traps; apply insecticidal soap or neem oil; introduce parasitic wasps
Increase humidity through regular misting; spray with water forcefully; use miticide or neem oil if severe
Spray with water or insecticidal soap; use neem oil; attract ladybugs with alyssum or yarrow

Uses

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Leafy Green Vegetable

Culinary

Tender leaves and purple stems are eaten fresh in salads or cooked as a nutritious side vegetable with a mild flavor similar to spinach. Popular in Asian stir-fries, soups, and curries; both leaves and young stems are entirely edible. [source]

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Nutritional Superfood

Medicinal

Extremely high in vitamins A, C, and K, as well as minerals like iron, calcium, and magnesium. Amaranth greens are traditionally used in Okinawan and Asian folk medicine for promoting overall health and vitality. [source]

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Natural Dye

Household

The purple-red pigmentation in stems and leaves can be extracted for natural dye production, creating beautiful pink to purple hues in textiles and crafts. [source]

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Seeds & Grain

Culinary

If allowed to mature, Amaranth produces tiny nutritious seeds that can be harvested, dried, and ground into flour or popped like popcorn for added nutrition. [source]

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Bird & Pollinator Food

Wildlife

Flowering plants attract hummingbirds, butterflies, and beneficial insects; mature seed heads provide food for birds during late season. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

Begin harvesting when plant reaches 8-12 inches tall by pinching off tender leaf tips and upper stem sections. Harvest regularly (every 5-7 days) to encourage continued branching and prevent flowering. Young leaves and stems are most tender and flavorful. Cut 3-4 inches from the top of stems, leaving lower leaves intact for regrowth. Morning harvest after dew dries yields crispest leaves. In tropical climates, can be harvested year-round; in cooler zones, harvest before first frost.

Fun Facts

🌱 Okinawan Amaranth is a staple vegetable in Okinawa, Japan, where it has been cultivated for centuries and is considered a longevity food due to the region's population of centenarians.
🌱 Amaranth seeds were a sacred crop of the Aztecs and can be popped like tiny popcorn kernels—just ¼ teaspoon of seeds yields about 1 cup of popped amaranth.
🌱 The plant is extremely prolific and heat-loving, making it one of the most productive leafy greens per square foot, especially in tropical and subtropical climates.

Gardening Terms

New to gardening? Learn about terms used in this guide:

Full Sun True Leaves

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