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A freshly pulled White Grano onion showing its sweet white top-shaped bulb and roots

How to Grow White Grano Onions From Seed

By Maxim Kaufman — Founder & CEO, Organo Republic

Updated July 2026

White Grano PRR is an early, very sweet white onion with a top-shaped bulb and mild, juicy flesh, and it carries pink root rot resistance for healthier plants. It is a short-day type that matures quickly, making it a favorite for Southern gardens. Here is what makes this variety special and how to get the best from it.

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This is the quick guide to White Grano PRR. For the full step-by-step on starting seeds, sowing, feeding, and troubleshooting onions, see our complete guide to growing onions from seed.

Quick start

Start seeds indoors about 8 to 10 weeks before your last frost, or sow in fall where winters are mild. Transplant seedlings 4 to 6 inches apart in full sun and rich soil, keeping them evenly watered and weed-free. Harvest in about 100 days once the tops fall and yellow.

Best tip

White Grano is a short-day onion, so it bulbs best in the South or when fall-sown in mild-winter regions; its pink-root-rot resistance helps in beds where onions have grown before. It is a sweet, fresh onion rather than a keeper, so plan to eat the crop soon after harvest.

At a glance

Botanical nameAllium cepa

Plant typeShort-day sweet onion

USDA zones3 to 9 (grown as an annual)

SunFull sun (6 or more hours)

Days to maturity100 days

Height12 to 18 inches

Spacing4 to 6 inches apart

WaterSteady and even; about 1 inch a week

Uses

White Grano is prized for its sweet, mild, juicy flesh, wonderful raw in salads and salsas or on sandwiches and burgers. It is a parent of many classic sweet onions, so expect the same gentle flavor. Use it fresh, as it does not store for long.

Frequently asked questions

How long does White Grano onion take to grow?

About 100 days from transplant, plus roughly 8 to 10 weeks of indoor growing first, making it an early sweet onion.

What does PRR mean on White Grano?

PRR stands for pink root resistance, a valuable trait that helps the plants stay healthy in soils where the pink root fungus is present.

Is White Grano a sweet onion?

Yes, it is very sweet and mild with juicy white flesh, closely related to other famous sweet onions. It is best eaten fresh rather than stored.

Where does White Grano grow best?

As a short-day onion it grows best in the South or in mild-winter regions where it can be fall-sown for early summer bulbs.

Ready to grow your own? Our 8 Onion Variety Pack lets you grow White Grano PRR alongside seven other onions from a single order. For the full step-by-step, see our complete onion growing guide linked at the top of this page.

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By Maxim Kaufman — Founder & CEO, Organo Republic

Maxim founded Organo Republic in 2017 and personally selects, tests, and grows the heirloom, non-GMO varieties the company offers. Under his leadership, Organo Republic was named Agri Business Review’s Top Non-GMO Seed Variety Solution 2026.