Introduction & History

Purple Top White Globe Turnip (Brassica rapa var. rapa 'Purple Top White Globe') is a biennial root vegetables vegetable in the Brassicaceae family, growing to 30 cm tall with a 15 cm spread. It develops purple-white roots ready for harvest in approximately 50 days from sowing. Hardy in USDA zones 3-10, it thrives in full sun with moderate watering and prefers soil pH 6.0-7.5.

History & Origin

Root vegetables were among the earliest foraged foods, with wild carrots, parsnips, and beets gathered across Eurasia for millennia before domestication. Many were selected from bitter, fibrous wild ancestors into the sweet, tender crops we grow today. Purple Top White Globe Turnip has been cultivated as a valued garden variety, selected for its purple-white roots and reliable performance across a range of growing conditions.

Botanical Description

Brassica rapa var. rapa 'Purple Top White Globe' is a biennial member of Brassicaceae, forming a bushy/compact plant reaching 30 cm tall. The edible root is purple-white, round in shape. Above-ground foliage is green. The root system is deep and taproot-based.

Varieties & Selection

Within the Brassica genus, numerous varieties have been developed for different climates, uses, and growing conditions. Select varieties suited to your growing conditions, space, and culinary preferences. Disease-resistant varieties reduce the need for chemical intervention.

Selection Criteria

Root shape is critical for your soil type: long varieties (Nantes, Imperator carrots) need deep, stone-free soil; short/round types (Paris Market, Chantenay) tolerate heavier soils and containers. For storage, choose maincrop varieties bred for keeping quality. Bolt-resistant varieties are important for spring-sown beetroot and parsnips in areas with unpredictable spring weather.

Planting & Sowing

Grow in full sun (6-8+ hours direct) in well-drained, fertile soil with pH 6.0-7.5. Direct sow when soil temperature reaches 8°C. Seeds germinate in 10 days at optimal temperature (10-20°C). Space plants 15 cm apart in rows 30 cm apart.

Soil Preparation

Root crops demand deeply worked, stone-free soil for straight, uniform development. Heavy clay soils cause forking, splitting, and misshapen roots. Sandy loams and silty loams are ideal. Never apply fresh manure — it promotes excessive branching and hairy root development. Incorporate well-composted organic matter 6+ months before planting. For heavy soils, build raised beds 20–30 cm deep filled with a 3:1 mix of garden soil and sharp sand. Soil pH requirements vary: carrots (6.0–6.8), beetroot (6.5–7.5), parsnips (6.0–7.0).

Climate & Hardiness

Purple Top White Globe Turnip grows in USDA zones 3-10 and tolerates temperatures down to -5°C. Protect from hard frosts with fleece or cloches. In mild climates, autumn sowings can overwinter for early spring harvests.

Growing & Training

Purple Top White Globe Turnip grows as a self-supporting bush and requires no special training or staking.

Group-Specific Growing Guide

Root vegetables store energy as sugars and starches in their enlarged taproots or hypocotyl regions. Soil preparation is critical — heavy, compacted, or rocky soils cause forking, splitting, and misshapen roots. Work beds to 30+ cm depth and remove stones. Fresh manure causes branching and hairy roots; use only well-rotted compost. Many root crops (carrots, parsnips, beetroot) improve in sweetness after exposure to light frost, as the plant converts starch to sugars as a natural antifreeze mechanism. Thinning at the seedling stage is essential — overcrowded roots compete for space and produce undersized, deformed crops.

Watering & Feeding

Watering

Water deeply once or twice per week, allowing the top 2-3 cm of soil to dry between waterings. Increase frequency during heatwaves and fruiting. Consistent moisture prevents cracking and blossom end rot.

Feeding

Moderate feeder. Avoid high-nitrogen fertilizer which promotes leaf growth at the expense of roots. Apply balanced or high-potash feed. Do not use fresh manure — it causes forking in root crops.

Propagation & Seed Saving

Seed saving difficulty: moderate. Brassicas cross-pollinate by insects — cage or isolate by 1km+ for pure seed. Most are biennial, flowering in year 2 after vernalization.

Seed Saving — Detailed Guide

Most root vegetables are biennial — they produce foliage in year one and flower/seed in year two. For seed saving, select the best roots at harvest, overwinter them in damp sand at 1–4°C, and replant in spring. Carrots, parsnips, and beetroot will bolt and produce umbel or spike flower heads. Carrots are insect-pollinated and will cross with wild carrot (Queen Anne's lace) — isolate by 500+ metres or use caging with introduced pollinators. Beetroot is wind-pollinated and crosses readily with chard and sugar beet. Radishes bolt quickly in long days, making summer seed production straightforward for spring varieties.

Diseases & Pests

Common Diseases

Group Disease Reference (Root Vegetable)

• Carrot cavity spot (Pythium violae) — oval depressions on roots; improve drainage; avoid compacted soil
• Sclerotinia rot — white fluffy mould; remove affected plants; crop rotation
• Violet root rot (Helicobasidium purpureum) — purple mycelium on roots; long crop rotation; improve soil drainage
• Powdery mildew — on parsnip foliage; usually cosmetic in late season; resistant varieties

Group Pest Reference

• Carrot root fly (Psila rosae) — larvae tunnel into roots creating rusty brown galleries; fine mesh barriers 60 cm high; delayed sowing (after late May); intercrop with onions (scent masking)
• Wireworm (Agriotes spp.) — tunnel into roots; common in newly broken grassland; trap with potato baits
• Aphids — root aphids can infest underground; foliar aphids spread virus diseases; encourage natural predators

Companion Planting & Crop Rotation

Crop Rotation

Purple Top White Globe Turnip belongs to no specific rotation group. It can be fitted into most rotation schemes flexibly. Avoid planting in the same spot annually to prevent soil-borne disease buildup.

Container Growing

Purple Top White Globe Turnip can be grown in containers. Use a pot at least 20 cm diameter and 20 cm deep. Ensure excellent drainage and feed every 2 weeks with liquid fertilizer once fruiting/growing begins.

Group Container Guide — Root Vegetable

Short-rooted varieties are essential for container growing — 'Paris Market' (round) carrots, 'Boltardy' beetroot, and 'Cherry Belle' radishes are reliable choices. Use deep containers (30+ cm for carrots) filled with stone-free, sandy compost mix. Round and Chantenay carrot varieties outperform long types in containers. Thin seedlings ruthlessly — overcrowded roots will be stunted. Keep compost consistently moist but not waterlogged. Radishes are the fastest container crop (25–30 days seed to harvest) and make excellent catch crops between slower-growing plants.

Harvesting & Storage

Harvest Purple Top White Globe Turnip when roots reach full size but before over-maturity. Roots are typically ready 50 days after sowing. Test-dig one root to check size before harvesting the row. Use a fork rather than a spade to avoid damage.

Group Harvest Guide — Root Vegetable

Root vegetables should be harvested based on size rather than calendar days — check by gently loosening soil around the shoulder. Carrots are sweetest at finger-thickness (2–3 cm diameter); overmature roots become woody. Parsnips benefit from frost exposure — the conversion of starch to sugar improves sweetness. Beetroot is best harvested at golf-ball to tennis-ball size; larger roots become fibrous. For long-term storage, twist off foliage (do not cut — cutting causes bleeding in beetroot) and store in boxes of damp sand in a cool (1–4°C), frost-free location. Parsnips and Jerusalem artichokes can remain in the ground through winter and be lifted as needed.

Storage

Store Purple Top White Globe Turnip in cool dry conditions. Expected storage life: 4 weeks under optimal conditions. Cure in warm, humid conditions for 1-2 weeks before long-term cool storage (2-4°C, 90-95% humidity). Don't wash before storing.

Preservation Methods

Root cellar: Store unwashed in sand/sawdust at 2-4°C, 90-95% humidity. Freezing: Blanch cubed/sliced pieces 3 minutes, cool rapidly, freeze. Canning: Pressure can only (low-acid). Dehydrating: Slice thin, dehydrate at 52°C for 6-10 hours.

Culinary Uses & Nutrition

Roasting at high heat (200°C+) caramelizes natural sugars through the Maillard reaction. Many roots (carrots, parsnips, beetroot) sweeten dramatically after frost as starch converts to sugar as a natural antifreeze. Purple Top White Globe Turnip is a versatile ingredient used across multiple cuisines.

Preserving, Succession & Planning

Root cellar: Store unwashed in sand/sawdust at 2-4°C, 90-95% humidity. Freezing: Blanch cubed/sliced pieces 3 minutes, cool rapidly, freeze. Canning: Pressure can only (low-acid). Dehydrating: Slice thin, dehydrate at 52°C for 6-10 hours.

Year-Round Growing Calendar

Maximise your productivity with Brassica rapa var. rapa 'Purple Top White Globe' by planning across the full year:

• Late winter (Feb–Mar): Order seeds, clean and repair equipment, plan crop rotations, start indoor sowings for warm-season crops
• Spring (Apr–May): Direct sow hardy crops, transplant indoor-started seedlings after hardening off, apply compost and mulch
• Summer (Jun–Aug): Main growing and harvesting season; succession sow for autumn; water consistently; monitor for pests
• Autumn (Sep–Nov): Harvest storage crops, sow overwintering varieties, clear spent plants, incorporate green manures
• Winter (Dec–Jan): Process and store harvests, plan next season, maintain tools, order seed catalogues

Frequently Asked Questions

Seasonal Care Calendar