Red onion 'Red Baron'

Sun

Full sun, ideally at least 6-8 hours of direct sunlight daily.

Water

Keep evenly moist during leaf growth and bulb swelling, without waterlogging. Reduce watering as the tops yellow and fall over.

Soil

Fertile, well-drained loam with a pH around 6.0-7.0; avoid compacted soil and freshly applied manure.

Height

1-2 ft (0.3-0.6 m)

Spread

0.3-0.5 ft (0.1-0.15 m)

Flowers

If allowed to flower, rounded heads of small white flowers appear in summer, usually in the second year; flowering reduces bulb quality.

Foliage

Upright, hollow, tubular blue-green leaves that yellow and collapse as the bulb matures.

Growth

Moderate; produces a harvestable bulb in one growing season.

Care needed

Medium

• Low allergen
• Edible

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   0.5 ft (0.15 m)

2. After 1 year

   1.5 ft (0.45 m)

   full size

Full size in one season.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Growth rate

Moderate

• Plant seedlings or sets 4-6 in (10-15 cm) apart; leave the tips of sets just visible above the soil.
• Water during dry spells so the shallow root zone stays evenly moist.
• Apply a balanced vegetable fertiliser before planting; avoid heavy nitrogen feeding once bulbs begin swelling.
• Weed frequently by hand or hoe shallowly to avoid damaging roots and bulbs.
• Use a light mulch to conserve moisture, keeping it clear of bulb necks.

Pruning. Do not trim healthy leaves or bend the tops over to force ripening. Remove flower stalks promptly and use those bulbs first; trim dried foliage only after curing.

Lift individual plants early for use as spring onions, or harvest mature bulbs in summer to early autumn when most tops have yellowed and fallen naturally and the necks are soft. Loosen the soil with a fork, lift gently, and cure the bulbs in a dry, airy, sheltered place until the skins and necks are fully dry.

Late winter

Sow seed under cover in modules where a long growing season is needed; use your local Southern or Northern Hemisphere season.

Early spring

Prepare a sunny bed with mature compost and a balanced fertiliser once the soil is workable.

Spring

Plant sets or hardened-off seedlings when the soil is no longer waterlogged; protect newly planted sets from birds.

Late spring

Thin seedlings to their final spacing, weed carefully and water during dry weather.

Summer

Maintain moisture while bulbs swell, remove any flower stalks, and stop feeding.

Late summer to early autumn

Harvest when the tops fall naturally, cure thoroughly and move sound bulbs into ventilated storage.

Autumn

Clear crop debris and plan a different bed for next year's onions to reduce soil-borne disease.

• Plant in straight rows in a potager for a neat, productive pattern.
• Use as a low seasonal crop in raised beds, with taller vegetables positioned where they will not shade it.
• Alternate rows with lettuce or beetroot for contrasting leaf shapes and colours, leaving enough room for bulb development.
• Grow in deep containers on a sunny patio where bed space is limited.

Garden styles it suits: Potager (kitchen garden), Edible landscape, Homestead, Cottage garden, Formal and Small-space.

Plant it with: Lettuce, Carrot, Beetroot, Swiss chard, Parsley and Calendula.

Wildlife: Flowers attract bees and other pollinating insects if plants are left to bloom, but a bulb crop is normally harvested before flowering.

• Onion fly or onion maggot: larvae damage roots and bulbs; use insect-proof mesh from planting, rotate crops and remove infested plants.
• Thrips: silvery streaks and distorted leaves are worse in hot, dry weather; maintain even moisture, remove nearby weeds and use locally approved controls if damage is severe.
• Onion white rot: yellowing plants develop white fungal growth and black resting bodies at the bulb base; remove affected plants and surrounding soil, and avoid growing alliums in that ground for many years.
• Bolting or poor bulb formation: cold stress can trigger flowering, while unsuitable day length prevents good bulbing; plant at the locally recommended time and use a short-day variety instead in low-latitude regions.

All parts, including bulbs, leaves and flowers, are toxic to cats, dogs and horses, whether raw, cooked or dried, and can cause serious red blood cell damage. Onions are not normally toxic to people when eaten as food, though they can cause digestive upset or allergic reactions in susceptible individuals.

• Red shallot (Allium cepa Aggregatum Group)

  Shallots usually form clusters of smaller, often elongated bulbs; 'Red Baron' normally forms one rounded bulb per plant.

• Red spring onion (Allium cepa)

  Young red bulb onions can look identical to red spring onions. Check the variety label: 'Red Baron' develops a substantial storage bulb under suitable long-day conditions.

The botanical name combines Allium, the Latin name for garlic, with cepa, Latin for onion.

Propagation. Grow from purchased seed or sets sold as 'Red Baron'. Sow seed shallowly in modules or a prepared seedbed; saved seed may cross with other flowering onions and may not reproduce the cultivar reliably.

Accepted botanical name

Allium cepa

In the US and Canada

Introduced in the lower 48 states and Pacific Basin.

Native range

Turkmenistan.

Measured

Average height 56 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.