Tat soi (Brassica rapa var. rosularis)

Overview

Tat soi, scientifically known as Brassica rapa var. rosularis, is a highly versatile member of the cabbage family valued for its attractive, rosette-forming foliage. This cool-weather crop presents thick, lustrous, black-green leaves that can range from smooth to puckered texture, offering visual interest alongside culinary utility. Gardeners appreciate Brassica rapa var. Rosularis for its relatively fast maturation, often ready for harvest in seven to eight weeks when cared for properly.

Whether grown for its young leaves in salads or its mature rosettes in stir-fries, Tat soi provides flavor similar to the popular pak choi. This plant is adaptable, featuring both prostrate and upright varieties, making it suitable for ground cover while simultaneously serving as a delicious, nutrient-dense vegetable addition to the garden rotation.

Fast Facts

• Plant Family: Brassicaceae
• Plant Type: Annual
• Hardiness Zones: USDA Zones 2-11
• Size at Maturity:
  • Height: 0.5-1 ft
  • Spread: 1-1.5 ft
• Bloom Time: Flowers not showy
• Sun Exposure: Full sun to part shade
• Water Needs: Medium
• Maintenance Level: Medium

How to Grow

Brassica rapa var. rosularis thrives when planted in fertile, moisture-retentive soil. As a cool weather crop, timing is crucial for success; sow seeds in late spring for a summer harvest or again in late summer for a robust fall planting. Be cautious planting in summer, as excess heat can quickly encourage Brassica rapa var. rosularis to bolt, ending leaf production.

Provide consistent, medium watering, especially during dry spells, to prevent bolting. Thin seedlings carefully once they establish: aim for 6 to 8 inches between plants with 12 to 18 inches between rows. If you are aiming for very large rosettes of Tat soi, thin them further to 12 to 16 inches apart.

Protection from pests like flea beetles is important, particularly when plants are young. Prostrate varieties of Tat soi demonstrate excellent cold hardiness, surviving temperatures down to -5 to -10°F, while upright forms can handle a light frost. Harvest individual leaves as needed, or take the entire head about an inch above the base to stimulate regrowth from the central rosette.

Landscape Uses

Beyond its primary role as a vegetable, Tat soi acts as an attractive edible border for flower beds due to its defined rosette structure and lustrous dark foliage. The differing leaf textures—flat versus crepe-like—add subtle variation when interplanted with other low-growing annuals.

When incorporating Brassica rapa var. rosularis into the landscape design, consider neighboring plants with similar water needs. Its compact growth, spreading up to 1.5 feet, makes it suitable for use in large containers or window boxes where its form can be fully appreciated before harvesting.

Standout Features

Noteworthy Characteristics

*Brassica rapa<.Em> var. Rosularis, known as tat soi, rosette pak choi or flat cabbage, has very thick lustrous black green leaves arranged in a rosette of regular, concentric circles, with prostrate and upright varieties. The leaves vary from flat and smooth to puckered and crepe-like. This is an attractive plant with potential as a border for flower beds and ground cover as well as a vegetable.

Recommended Uses

Similar in flavor to pak choi, tat soi can be used at all stages: seedling leaves, small rosettes, large plants, and young flowering shoots. Young leaves and small rosettes are used raw in salads and stir fry. Tat soi may also be cooked in soups, sautéed, or added to pasta.

Tolerances

• Slugs
• Snails
• Cutworms
• Flea beetles

Potential Problems

Pests commonly target Tat soi foliage, making vigilant scouting necessary. Slugs and snails are attracted to the lush, tender leaves and can cause significant cosmetic damage, especially in damp conditions. Cutworms may sever young seedlings near the soil line shortly after they emerge.

Flea beetles are a primary concern, creating small, shot-hole damage on the leaves. To manage these issues effectively, maintain good garden hygiene and consider using row covers early in the season for flea beetle protection. For slugs and snails, handpicking or deploying organic baits around the base of the Brassica rapa var. rosularis plants is often effective.

Frequently Asked Questions

What hardiness zones is Tat soi suitable for?

Tat soi, or Brassica rapa var. rosularis, is exceptionally hardy, thriving across USDA Zones 2 through 11.

How large does Tat soi grow?

This vegetable typically reaches a height between 0.5 and 1 foot tall with a spread ranging from 1 to 1.5 feet at maturity.

What sun exposure does Tat soi need?

Brassica rapa var. Rosularis prefers locations receiving full sun to partial shade for optimal growth and highest yields.

When does Tat soi bloom?

Tat soi produces flowers that are generally not showy, often indicating the heads are beginning to bolt when flowering begins.

Companion Planting

When planning your vegetable patch, consider planting Tat soi near strong-smelling companions that naturally deter common brassica pests. Because Brassica rapa var. rosularis requires consistent moisture, pairing it with heavy feeders that don’t compete too aggressively for root space is beneficial. Root vegetables like carrots or radishes can often share space effectively, provided the soil preparation is uniform.

Avoid planting Tat soi immediately adjacent to other members of the Brassica family unless absolutely necessary, as this can increase the localized risk of disease or pest outbreaks affecting the entire group. Succession planting small batches of Brassica rapa var. rosularis every few weeks will ensure a continuous supply of young, tender leaves throughout the cool growing seasons.

Seasonal Care Calendar

For spring crops of Tat soi, focus on establishing protection if temperatures are still erratic, utilizing row covers to buffer against unpredictable cold snaps or early intense summer heat. Once summer ends, late-summer plantings require consistent watering as they mature during cooler autumn days, maximizing leaf size before the first hard freeze.

During the primary growing phase, monitor soil moisture carefully; dryness encourages premature flowering (bolting) in this variety of Brassica rapa. Harvesting individual leaves helps delay the final bolting process, allowing the plant to maintain productivity longer into the season under ideal temperatures.

Conclusion

Brassica rapa var. rosularis provides gardeners with a resilient, attractive, and highly functional cool-season vegetable perfect for fresh eating. The unique rosette form of Tat soi makes it an excellent addition to edible landscapes. Ensure you plan your planting schedule around the moderate temperatures it prefers, and you will be rewarded with succulent leaves throughout the cooler parts of the year.