Red Marble

Onion

90d to harvest

Aromas of sweet earth and gentle bite rise from each jewel-like bulb—Red Marble delivers compact, perfectly round cipollini onions with a glossy, garnet-red skin that peels back to reveal crisp, pale rose interiors. The texture is satisfyingly firm yet tender, with a balanced flavor that sweetens beautifully when roasted and shines in fresh preparations, as well as in sauces and quick pickles. For gardeners who love precision, this 90-day variety rewards careful spacing with uniform “marbles” that look as good as they taste.

Crop Dates

Growing note: In frost-free Zone 10a, grow this cool-season crop during the cooler dry season (October–February).

Milestone	Date
Start Indoors	—
Climate	Frost-Free Climate
Transplant / Sow Outdoors	Oct 1st
Harvest Begins	Dec 30th
Harvest Ends	Feb 28th

Crop Details

Trait	Value
Days to Maturity	90
Sun Requirements	Full Sun
Growth Habit	Bulbing
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	65
Min Soil Temp (°F)	45
Min Night Temp (°F)	35
Harden Off (days)	7

Frequently Asked Questions

What pest or disease issue commonly affects Allium cepa (red cipollini-type onions), and how can I manage it?

Onions (Allium cepa) commonly suffer from onion thrips, which cause silvery streaks and distorted, dried leaf tips. Spray plants with insecticidal soap and repeat every 5–7 days until new growth is normal, and remove heavily damaged leaves to reduce thrips habitat. Also watch for purple blotch/leaf blight (dark lesions that spread on leaves); keep foliage dry by watering at the soil line and improve airflow between plants.

How often should I water Allium cepa during the main growing phase to form good bulbs?

During bulb formation (roughly mid-season until leaves start yellowing), keep the top 2–3 in (5–8 cm) of soil evenly moist but not waterlogged. Water about 1–2 times per week with deep soakings, adjusting so you don’t see standing water and the soil still crumbles when squeezed. Once bulbing is underway, avoid letting the soil completely dry out for long stretches, since irregular moisture can lead to smaller bulbs and uneven maturity.

How do I know when Allium cepa (Red Marble-type onions) is ready to harvest?

Harvest when about 50–70% of the tops have fallen over and the remaining leaves are yellowing, typically around 90 days from planting. Gently lift one bulb to check size—bulbs should feel fully formed and the neck should be tight rather than soft. Stop watering a week before harvest so skins cure better, then cure in a dry, airy spot out of direct sun until outer skins are papery.