What hardiness zones is Brassica rapa 'Hakurei' suitable for?

Brassica rapa 'Hakurei' is a compact, fast-maturing annual root vegetable in the mustard family (Brassicaceae) reaching 8–14 inches (20–35 cm) tall with a 6–10 inch (15–25 cm) spread. This Japanese hybrid cultivar (F1) produces a smooth, white, globe-shaped root 2–3 inches (5–8 cm) in diameter with thin skin, crisp texture, and a mild, sweet, fruity flavor — unlike the pungent, fibrous roots of traditional European turnips. Flesh is white, fine-grained, juicy. Leaves are medium green, oblong to spatulate, lightly hairy, 6–10 inches (15–25 cm) long, edible as cooking greens. Root formation is rapid: harvest-ready in 38–45 days from direct sowing. The thin skin does not require peeling. Performs in cool weather; bolts rapidly when day length exceeds 14 hours or temperatures exceed 80°F (27°C). In the Pacific Northwest, spring and fall sowings produce the highest-quality roots. Roots become pithy if left in the ground past 3 inches (8 cm) diameter.

Native Range

The species Brassica rapa is native to central Asia and the Mediterranean region. 'Hakurei' is a Japanese F1 hybrid developed for salad-quality fresh eating. Introduced to North American markets in the 1990s and has become the standard Japanese salad turnip cultivar in market gardens.

Suggested Uses

Planted in vegetable gardens, salad gardens, containers (3+ gallon), and market gardens. Eaten raw in salads, sliced with sea salt, or with dips — the sweet, apple-like crunch is the primary culinary feature. Roots are also roasted, glazed, or added to stir-fries. Greens are sautéed or braised. The rapid maturity (38–45 days) makes 'Hakurei' a standard succession-sowing crop and a soil-building rotation component between cover crop plantings.

How to Identify

Distinguished from traditional European turnips ('Purple Top White Globe') by the entirely white, smooth skin (versus purple-topped), the mild sweet flavor (versus pungent), and the smaller size at harvest (2–3 inches versus 3–5 inches). Distinguished from radish (Raphanus sativus) by the white, globe-shaped root with green-topped foliage (versus red, elongated, or daikon-type roots), and the milder brassica (versus sharp radish) flavor. The thin, smooth white skin and sweet, apple-like crunch are diagnostic.

Appearance

Size & Dimensions

Height8" - 1'2"

Width/Spread6" - 10"

Colors

Flower Colors

yellow

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~2 weeks

Spring

Bolts rapidly in response to long days (14+ hours) or heat above 80°F (27°C). Flowers are yellow, four-petaled (typical Brassicaceae cruciform). Primarily grown as a spring and fall crop to avoid bolting. If bolting occurs, remove the flowering stalk — the root becomes woody and inedible once the plant bolts.

Detailed Descriptions

Flower Description

Yellow (if allowed to bolt)

Foliage Description

Medium green, oblong to spatulate, lightly hairy, with toothed margins

Growing Conditions

Sun Requirements

Full Sun Partial Shade

Requires 4-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

loam silt sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Care & Maintenance

Care Guide

Direct sow seeds 0.25 inch (6 mm) deep in early spring (4–6 weeks before the last frost) or in late summer (August–September) for fall harvest. Space 4 inches (10 cm) apart in rows 12 inches (30 cm) apart. Thin seedlings when 2 inches (5 cm) tall — thinnings are edible. Consistent moisture produces crisp, non-pithy roots. Harvest at 2–3 inches (5–8 cm) diameter, 38–45 days after sowing. Do not delay harvest; roots become pithy and hollow within days of reaching mature size. In the Pacific Northwest, fall sowings (August–September) produce the sweetest roots as cooling temperatures increase sugar content. Flea beetles may damage seedling-stage leaves; floating row cover prevents damage.

Pruning

No pruning applicable. Harvest entire plants by pulling. Greens are edible and can be harvested as a cut-and-come-again crop if roots are not the primary objective.