Red Amposta

Onion

Zone 10a Save Garden

🌱 95d to harvest Bulbing

Rich, wine-red skins glow with a satin sheen, opening to a sweet, mellow interior that’s tender rather than sharp—ideal for garde…

Crop Dates

Milestone	Date
Start Indoors	Nov 7th
Last Frost	Jan 16th
Transplant / Sow Outdoors	Jan 16th
Harvest Begins	Apr 21st
Harvest Ends	Dec 19th

Crop Details

Trait	Value
Days to Maturity	95
Sun Requirements	Full Sun
Growth Habit	Bulbing
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	70
Min Soil Temp (°F)	45
Min Night Temp (°F)	35
Harden Off (days)	7

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Frequently Asked Questions

What pest or disease problem commonly affects Allium cepa (red onions like Red Amposta), and how can I control it?

Onions (Allium cepa) commonly suffer from purple blotch (Alternaria porri) and other leaf blights that show as purple-brown spots on foliage. Improve airflow by spacing plants properly, water at the base (not on leaves), and remove badly spotted leaves; if outbreaks persist, apply a labeled fungicide intended for onions/leaf blights following the product’s schedule. Avoid replanting onions in the same bed in consecutive seasons to reduce carryover of fungal spores.

How often should I water Allium cepa during the main growing phase, and what soil moisture level is ideal?

During active bulb growth, keep the soil consistently moist but not soggy—aim for roughly 1 inch (2.5 cm) of water per week, adjusted for rainfall and your soil’s drainage. Water deeply when the top 1–2 inches (2.5–5 cm) of soil dry out, because onions need steady moisture to form well-sized bulbs. Once bulbs start swelling and the plants are about mid-season, reduce watering gradually to help the necks dry and prevent bulb rot.

How can I tell when Red Amposta onions are ready to harvest?

Harvest when about 50–70% of the tops have fallen over and the necks feel dry and constricted, typically around 95 days for Red Amposta. Stop watering about 1–2 weeks before harvest to encourage curing-ready tops. Lift gently (don’t yank) and cure the bulbs in a dry, airy place with good ventilation until the outer skins are papery and the necks are tightly sealed.

Rich, wine-red skins glow with a satin sheen, opening to a sweet, mellow interior that’s tender rather than sharp—ideal for gardeners who want bold color with gentle flavor. Red Amposta forms well-filled bulbs with a classic globe shape and crisp, layered texture that holds up beautifully for roasting, caramelizing, and slow-simmered sauces. Grow it for standout fresh slices and vibrant pickling results, when its color turns especially jewel-like.

Sowing Tips

Transplant Conditions

Wait until soil reaches 45°F and nights stay above 35°F before moving outdoors. Harden off for 7 days first.

Expert Note

For the sweetest “red storage-type” bulbs, grow with consistent moisture and avoid nitrogen-heavy feeding once bulbs begin to swell.