Brassica juncea 'Osaka Purple', Osaka Purple Mustard Greens
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Vegetables

Brassica juncea 'Osaka Purple'

Osaka Purple Mustard Greens

BrassicaceaeAsia

At a Glance

Typevegetable
Habitupright rosette
Foliagedeciduous
Height8-12 inches
Width8-10 inches

Growing Zones

USDA Hardiness Zones

2a - 9b
Zone 2a
Zone 2b
Zone 3a
Zone 3b
Zone 4a
Zone 4b
Zone 5a
Zone 5b
Zone 6a
Zone 6b
Zone 7a
Zone 7b
Zone 8a
Zone 8b
Zone 9a
Zone 9b
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Overview

Brassica juncea 'Osaka Purple' is a striking cool-season leafy vegetable cultivar distinguished by its vibrant purple-red foliage with contrasting green undersides. This mustard green variety forms attractive rosettes of deeply lobed, serrated leaves that can reach 8-12 inches in length. The leaves have a tender texture when young and develop a more pronounced spicy, peppery flavor as they mature. The plant produces sturdy stems and maintains its colorful appearance throughout the growing season, making it both ornamental and edible. When allowed to bolt, Brassica juncea 'Osaka Purple' produces small yellow flowers typical of the Brassicaceae family, though it is primarily grown for its flavorful leaves rather than flowers or seeds.

Native Range

Brassica juncea is native to the foothills of the Himalayas and has been cultivated throughout Asia for thousands of years. Brassica juncea 'Osaka Purple' is a modern cultivar developed from these ancient Asian mustard varieties.

Suggested Uses

salad greens, stir-fries, braising, ornamental edible gardens, container growing, microgreens, baby leaf production

How to Identify

Brassica juncea 'Osaka Purple' can be identified by its distinctive purple-red leaves with green undersides and deeply serrated, lobed margins. The leaves are broader than many other mustard varieties and have prominent white or pale veining. Young plants form compact rosettes, while mature plants develop upright growth habits. The stems are sturdy and often show purple coloration, and the plant has a characteristic spicy, pungent aroma when leaves are crushed.

Appearance

Bloom Information

late spring to early summer if allowed to bolt

Detailed Descriptions

Flower Description

yellow

Foliage Description

purple-red with green undersides and white veining

Growing Conditions

Sun Requirements

full sun to partial shade

Soil pH

6.0-7.5

Water & Climate

Water Needs

moderate, consistent moisture

Frost Tolerance

hardy

Time to Maturity

40-50 days

Care & Maintenance

Care Guide

Brassica juncea 'Osaka Purple' requires consistent moisture and cool weather conditions for optimal growth. Water regularly to maintain even soil moisture, but avoid waterlogged conditions which can lead to root rot. Apply a balanced fertilizer at planting and side-dress with nitrogen-rich fertilizer every 3-4 weeks during active growth. Mulch around plants to retain moisture and suppress weeds. In hot weather, provide afternoon shade to prevent bolting and maintain leaf quality. Cool temperatures enhance the purple coloration of the leaves.

Pruning

Brassica juncea 'Osaka Purple' benefits from regular harvesting rather than traditional pruning. Begin harvesting outer leaves when they reach 4-6 inches long, allowing the center to continue producing new growth. Remove any damaged or yellowing leaves promptly to maintain plant health. If flowers begin to form and seed production is not desired, pinch off flower stalks to encourage continued leaf production and prevent the leaves from becoming too bitter.

⚠️ Toxicity Warning

Brassica juncea 'Osaka Purple' is generally safe for human consumption when properly prepared. Raw leaves contain compounds that may cause digestive irritation in sensitive individuals if consumed in large quantities. Cooking reduces these compounds significantly. As with all brassicas, the plant contains glucosinolates which are beneficial in moderate amounts but may interfere with thyroid function if consumed excessively raw.

Planting Guide

Planting Methods & Timing

Planting Method

direct sow

Indoor Start

4 weeks before last frost

Direct Sow Timing

early spring, 2-4 weeks before last frost, and again in late summer for fall harvest

Days to Maturity

40–50 days

Plant Spacing

6 inches

Companion Planting

Good Companions

lettuce
spinach
radishes
carrots
onions
garlic
dill

Avoid Planting With

tomatoes
peppers
strawberries
other brassicas