Torpedo Onion
An Italian heirloom also called Rossa di Tropea, with an elongated torpedo shape and gorgeous magenta-pink skin.
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Meet Torpedo Onion
An Italian heirloom also called Rossa di Tropea, with an elongated torpedo shape and gorgeous magenta-pink skin. The flesh is incredibly sweet and mild, making this one of the best onions for eating raw in salads and sandwiches. The elongated shape produces uniform slices ideal for grilling and caramelizing. Plants need a long growing season and long day length to size up properly in northern latitudes.
When to plant Torpedo Onion
Start torpedo onion seeds indoors ten to twelve weeks before the last frost date. Sow seeds in deep cell trays or soil blocks, planting two to three seeds per cell about 0.5 cm deep. Maintain temperatures of 18-21 degrees Celsius for germination. Provide fourteen to sixteen hours of bright light daily. Thin to one seedling per cell when they have two true leaves. Trim tops to 10 cm height when they begin to flop to encourage thicker stems. Begin hardening off two weeks before transplanting by gradually exposing to outdoor conditions. Transplant when seedlings are pencil-thick and soil temperature is at least 10 degrees Celsius.
Your Torpedo Onion Year
Composed for Zone 7 · typical seasons · frost passes Apr 2, returns Nov 1
Sow Torpedo Onion Mar – May, pick Jul – Sep. Set your climate below and every date on this plate re-times itself.
How to grow Torpedo Onion
Torpedo onions require a long growing season of 110 days or more, so start seeds indoors ten to twelve weeks before the last frost. Sow seeds thinly in trays with fine seed-starting mix, barely covering them, and maintain a temperature of 18-21 degrees Celsius. Germination takes seven to fourteen days. Trim seedling tops to 10 cm when they flop over to encourage stocky growth. Harden off and transplant outdoors when soil temperatures reach 10 degrees Celsius.
Space transplants 12-15 cm apart in rows 30 cm apart in fertile, well-drained soil. Torpedo onions are intermediate to long-day varieties, requiring 14 or more hours of daylight to initiate bulbing. Consistent moisture is essential during the bulb formation phase, but reduce watering as tops begin to yellow and fall over. A balanced fertilizer every three weeks during active growth supports bulb expansion.
These onions are ready when about half the tops have fallen over naturally. Stop watering at this point and allow the bulbs to cure in the ground for a few days before lifting. The elongated shape makes them prone to sunburn during curing, so provide shade or cure indoors. Handle gently as the soft, sweet flesh bruises easily.
128 plants fit a 4 × 8 ft bed
Each Torpedo Onion wants 15 cm of elbow room. The planner keeps that spacing for you — every plant, every bed.
Torpedo Onion's best neighbours
Torpedo onions pair well with carrots, as the onion scent helps mask carrots from carrot fly. Plant alongside lettuce and beets, which benefit from the pest-deterrent qualities of alliums. Tomatoes and peppers are good neighbors, though avoid shading the onions as they need full sun. Chamomile planted nearby may improve onion flavor and vigor. Avoid planting near peas, beans, and other legumes, as alliums inhibit their nitrogen-fixing ability. Keep away from asparagus, which can be stunted by nearby allium plantings.
Carrot belongs beside it. Peas doesn't.
Old growers' knowledge, checked against Torpedo Onion's real companion table below — test any plant you're growing.
Related growing guides
Feed it well
Torpedo onions require deeply worked, loose soil to accommodate their elongated shape without restriction. Sandy loam with a pH of 6.0 to 6.8 is ideal. Incorporate well-rotted compost to a depth of 25 cm and add bone meal for phosphorus, which supports bulb development. Avoid heavy clay soils that can distort the torpedo shape. Apply a balanced organic fertilizer at transplanting and side-dress with nitrogen-rich amendments like blood meal every three weeks during the vegetative growth phase. Stop nitrogen application once bulbing begins to promote proper curing and storage quality.
Ideal Temperature
Hardiness Zone Compatibility
From seed to harvest, stage by stage
Seed Starting
Torpedo onion seeds are tiny and slow to germinate, taking 7-14 days at optimal temperatures. The first visible growth is a single thin, grass-like leaf (the flag leaf) that emerges in a loop before straightening upright. Seeds must be started indoors 10-12 weeks before the last frost because these long-season onions need every available growing day to produce full-sized bulbs.
Seedling Development
Seedlings develop additional tubular leaves and begin building the root system that will support bulb growth later. Growth is slow and steady during this phase. The thin, upright leaves may begin to flop when they reach 12-15 cm, which is the signal to trim them back to encourage thicker, sturdier stems and redirect energy into root development.
Vegetative Growth
After transplanting, plants establish in the garden and produce a fan of 6-10 upright tubular leaves. The root system expands rapidly into the surrounding soil. This phase is focused entirely on building the leaf canopy that will later fuel bulb growth — each leaf corresponds to one ring in the finished bulb, so more leaves means a larger onion.
Bulb Initiation and Expansion
As day length reaches the critical 14+ hour threshold, the plant shifts energy from leaf production into bulb formation. The base of each leaf swells and thickens, forming the concentric layers of the developing bulb. The distinctive elongated torpedo shape becomes visible as the bulb pushes partially above the soil line. This is the most water-critical phase of the entire growing cycle.
Maturation and Curing
Outer leaves begin to yellow from the tips downward as the plant redirects all remaining energy into the bulb. When about half the tops have fallen over naturally, the onion is signaling that it has finished sizing up. The neck softens and the outer skin begins to dry and tighten around the bulb, developing the characteristic papery magenta-pink wrapper.
Sow seeds 0.5 cm deep in deep cell trays or soil blocks filled with fine seed-starting mix. Maintain soil temperature at 18-21°C (65-70°F). Provide 14-16 hours of strong light daily from sowing — even before emergence — to produce stocky seedlings rather than weak, floppy ones.
Caring for Torpedo Onion month by month
What to do each month for your Torpedo Onion
July
You are hereBulbing begins as day length exceeds 14 hours. Stop nitrogen fertilization once bulb swelling is visible. Maintain even watering — this is the most water-sensitive phase. Do not hill soil around exposed bulbs. Watch for signs of downy mildew in humid weather and improve air circulation if needed.
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One email at the start of each month: what to sow, plant, and tackle right now — for your Torpedo Onion and everything growing around it. Plus a short starter course that helps you dodge the classic mistakes.
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Harvesting Torpedo Onion
Torpedo onions are ready to harvest when about half the green tops have fallen over naturally, typically in late July through August. Bend remaining upright tops gently to speed the curing process. After a few days, loosen soil with a fork and lift bulbs carefully. The elongated shape is prone to damage, so handle with care. Cure in a single layer in a warm, dry, well-ventilated area out of direct sunlight for two to three weeks until the neck is completely dry and the outer skin is papery. Trim roots and cut tops to 2 cm for storage.
assuming you sow when the window opens — set your real date
Pick Torpedo Onion promptly and the plant keeps producing.
Storage & Preservation
Torpedo onions have a shorter storage life than round onions due to their high sugar content, typically lasting two to three months in cool, dry conditions at 5-10 degrees Celsius. Braid them by their tops for attractive storage. Slice and freeze on trays for convenient cooking use year-round. Pickle thin torpedo onion rings in red wine vinegar for a tangy condiment. Caramelize large batches slowly and freeze in portions for quick use in soups and sauces. The sweet flesh also dehydrates well into crispy onion chips for snacking.
What goes wrong — and the fix
Onion Thrips
PestSilvery white streaks on leaves, leaf curling, and stunted growth. Severe infestations cause leaves to brown and collapse, reducing bulb size.
Downy Mildew
DiseaseGrayish-purple fuzzy growth on leaf surfaces, especially during cool, humid weather. Infected leaves turn yellow and collapse from the tip downward.
Onion Fly
PestYellowing and wilting of young plants, with small white maggots visible in the root zone and base of the bulb.
Botrytis Neck Rot
DiseaseSoft, gray decay at the neck of the bulb during storage, spreading downward through the flesh. Gray fuzzy mold develops on affected tissue.
Troubleshooting Common Problems
The most common issue is bolt-resistant torpedo onions running to seed prematurely due to cold stress during early growth. Avoid transplanting too early and protect from late cold snaps. Short, stubby bulbs instead of the characteristic torpedo shape often result from compacted or heavy clay soil. Double bulbs are caused by temperature fluctuations during the bulbing period. Sunscald during curing produces green, bitter patches on exposed bulbs. Poor storage life is usually due to insufficient curing or harvesting before the neck has fully dried. Splitting occurs from irregular watering during bulb expansion.
Growing Tips
- Start seeds early and do not rush transplanting. Torpedo onions need a full 110+ day growing season, so starting indoors 10-12 weeks before last frost is non-negotiable. Late-started plants run out of growing time before bulbs can fully size up.
- Trim seedling tops to 10 cm whenever they begin to flop — this may seem counterintuitive, but trimming redirects energy from floppy leaf length into root development and stem thickness. Pencil-thick stems at transplant time are the single best predictor of large bulbs at harvest.
- Soil preparation is critical for good shape. Torpedo onions need deeply worked, loose, stone-free soil to develop their characteristic elongated form. Compacted or rocky soil produces stubby, misshapen bulbs. Double-dig beds or grow in raised beds filled with sandy loam for the best results.
- Keep beds obsessively weed-free. Onions have shallow, sparse root systems and narrow upright leaves that cannot compete with weeds for light, water, or nutrients. Even modest weed pressure can reduce bulb size by 50% or more. Mulch lightly with straw after transplanting.
- Water is everything during bulb expansion. Torpedo onions need consistent, even moisture from transplanting through the start of top fall-over. Irregular watering during the bulbing phase causes splitting, double bulbs, and thick necks that resist curing. A soaker hose on a timer is ideal.
- Stop nitrogen fertilizer when bulbing begins. Late nitrogen promotes soft, lush growth that is susceptible to neck rot in storage and delays the natural curing process. Switch to a potassium-focused feed (like wood ash tea) to promote bulb firmness and storage quality.
- Handle harvested bulbs like eggs. The elongated torpedo shape and high water content make these onions much more prone to bruising and mechanical damage than round onions. Use a fork to loosen soil before lifting, and never pull bulbs by their tops — the neck can tear, inviting storage rot.
- Cure thoroughly before storage. Torpedo onions need 2-3 weeks of curing in a warm (24-30°C / 75-85°F), dry, shaded, well-ventilated location until the neck is completely dry and paper-thin when squeezed. Under-cured onions develop neck rot within weeks of storage.
Pick your Torpedo Onion
Rossa di Tropea
The classic Italian torpedo onion from Calabria with deep magenta skin, sweet white flesh, and outstanding raw eating quality.
Red Long of Florence
An Italian heirloom with deep red skin and pink-white flesh, extremely sweet and mild when eaten raw in salads.
Cipolla di Certaldo
A Tuscan variety with purple-red skin and flat torpedo shape, prized for its balanced sweet-sharp flavor in regional dishes.
Simiane
A French torpedo type with pale copper skin and very sweet white flesh, excellent for caramelizing and gratins.
Torpedo onions are a premium specialty product, commanding $4-8 per pound at farmers markets and gourmet grocers — and authentic IGP Cipolla di Tropea imported from Italy can sell for $10-15 per pound at specialty shops. A single $3-4 seed packet contains 200+ seeds, enough to grow far more onions than any household needs. Growing 40-50 bulbs from a single packet can produce 5-10 kg of torpedo onions worth $50-150 at retail prices. The savings are even more dramatic considering that torpedo onions are often only available seasonally at specialty markets, while home growers can harvest and store them for months.
Quick recipes
Grilled Torpedo Onion Rings with Balsamic Glaze
20 minThick cross-cut rings of torpedo onion brushed with olive oil and grilled over high heat until deeply charred and sweet. A balsamic reduction drizzled on top creates a perfect balance of smoky, sweet, and tangy. The torpedo shape produces uniform rings that hold together beautifully on the grill.
6 ingredientsClassic Italian Torpedo Onion and Tomato Salad
10 minThe simplest and most iconic way to enjoy torpedo onions — thinly sliced raw and tossed with ripe summer tomatoes, fresh basil, and the best olive oil you have. The extraordinary sweetness of Rossa di Tropea means no soaking in water is needed to tame harshness.
7 ingredientsSlow-Caramelized Torpedo Onion Jam (Cipollata)
50 minA traditional Calabrian condiment that concentrates the natural sugars of torpedo onions into a thick, glossy, deeply flavored jam. Slow cooking in red wine and a touch of vinegar produces a sweet-savory spread that is extraordinary on crostini, alongside cheese, or stirred into pan sauces.
9 ingredientsCulinary Uses
Torpedo onions are treasured for raw eating in Italian cuisine, where their sweet, mild flavor shines in summer salads and panini. Slice into thick rings and grill until charred and sweet. Roast whole in the oven until meltingly soft inside. Caramelize slowly for French onion soup with exceptional depth of flavor. The uniform torpedo shape produces perfect rings for frying. Pickle in balsamic vinegar for an elegant antipasto. Simmer in a traditional Italian onion jam called cipollata.
What's inside
Health Benefits
- Red and pink onion varieties like torpedo onions contain significantly higher levels of quercetin than white or yellow types — quercetin is one of the most studied dietary flavonoids, with research suggesting anti-inflammatory, antihistamine, and cardiovascular protective properties.
- Rich in organosulfur compounds that are released when the onion is cut, crushed, or chewed. These compounds, including allicin and diallyl sulfides, have demonstrated antimicrobial activity and may support cardiovascular health by inhibiting platelet aggregation.
- Contains prebiotic fibers (fructooligosaccharides and inulin) that selectively nourish beneficial gut bacteria, particularly Bifidobacteria. Regular consumption supports a healthy gut microbiome, which is increasingly recognized as central to immune function and metabolic health.
- The anthocyanin pigments responsible for the magenta-pink color provide antioxidant protection against oxidative stress. These pigments are most concentrated in the outer layers, so peeling minimally preserves the greatest nutritional benefit.
- Provides meaningful amounts of chromium, a trace mineral involved in insulin receptor function and glucose metabolism. Regular allium consumption has been associated with improved insulin sensitivity in observational studies.
- The mild, sweet flavor of torpedo onions encourages raw consumption, which preserves heat-sensitive nutrients like vitamin C and the enzyme alliinase that generates beneficial sulfur compounds. Cooking reduces these compounds by 30-60%, so raw torpedo onion in salads delivers the maximum health benefit.
Where Torpedo Onion comes from
The torpedo onion (Allium cepa) traces its roots to the ancient Mediterranean world, where elongated onion varieties were cultivated by the Greeks, Romans, and Phoenicians. The specific lineage of the Italian torpedo onion is believed to have arrived on the Calabrian coast of southern Italy through Phoenician traders who established colonies along the Tyrrhenian Sea more than 2,500 years ago. The sandy, well-drained coastal soils and mild maritime climate of Calabria proved ideal for developing the sweet, mild onion that would eventually become famous worldwide.
The town of Tropea, perched on dramatic cliffs above the sea in the province of Vibo Valentia, became the epicenter of torpedo onion cultivation. Over centuries, Calabrian farmers selected for the most elongated bulb shapes, the deepest magenta color, and above all, the mildest, sweetest flavor. The resulting variety — Cipolla Rossa di Tropea — became so renowned that it earned IGP (Protected Geographical Indication) status from the European Union in 2008, legally protecting its name and geographic origin. Only onions grown in the designated coastal strip of Calabria, from Amantea in the north to Nicotera in the south, can carry the Tropea name.
Beyond Italy, torpedo onion varieties spread throughout the Mediterranean and eventually worldwide. The Red Long of Florence (Rossa Lunga di Firenze) is a Tuscan relative, while the French Simiane and various Spanish torpedo types share the same elongated genetics adapted to local conditions. In the 20th century, Italian immigrants brought torpedo onion seeds to the Americas, where the variety gained devoted followings among home gardeners and specialty growers. Today, torpedo onions are cultivated commercially in Italy, France, Spain, and increasingly in California and other warm-climate regions of the United States. They remain a premium specialty product, commanding higher prices than standard onions in gourmet markets worldwide.
Torpedo Onion: did you know?
Fascinating facts about Torpedo Onion
The most famous torpedo onion in the world is the Cipolla Rossa di Tropea, which carries IGP (Indicazione Geografica Protetta) status from the European Union — a legal certification that only onions grown in the specific coastal zone of Calabria between Amantea and Nicotera can bear the Tropea name.
Torpedo Onion questions, answered
When should I plant Torpedo Onion?
What are good companion plants for Torpedo Onion?
What hardiness zones can Torpedo Onion grow in?
How much sun does Torpedo Onion need?
How far apart should I space Torpedo Onion?
What pests and diseases affect Torpedo Onion?
How do I store Torpedo Onion after harvest?
What are the best Torpedo Onion varieties to grow?
What soil does Torpedo Onion need?
Why are my torpedo onions forming short, round bulbs instead of the elongated torpedo shape?
Can I grow torpedo onions from sets or do I need to start from seed?
Why did my torpedo onions bolt (send up flower stalks) instead of forming bulbs?
How long can I store torpedo onions, and why do they not keep as long as regular onions?
What is the difference between Rossa di Tropea and Red Long of Florence?
Do torpedo onions need long days to form bulbs, or can I grow them in southern latitudes?
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From the “Growing guide” sectionCompanion conflicts, caught early
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Every harvest you log teaches it your garden. Next year's plan starts from what actually worked in your soil, not a textbook's.
From the “Overview” sectionPlant these alongside Torpedo Onion
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Keep Torpedo Onion away from these
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