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Gardening in Washington State

Why Are My Onion Bulbs So Small?

Onions form bulbs in response to day length or the number of hours of daylight. There are two main types of onions: those grown in northern latitudes that bulb in response to long days, and those grown in southern latitudes that bulb in response to short days. The long-day onions grown in Washington will start to bulb when there are 14 hours of daylight. If they are not planted early enough in the spring, bulbing will begin before the plant grows enough to produce a large bulb. When purchasing onion seed, Washington gardeners should be sure to select only long-day onion cultivars.

Onions
Photo credit: Licensed under GNU Free Documentation License 1.2 via Wikimedia Commons

For more information, download a free PDF of Growing Onions in Home Gardens.

Submitted by: Marianne Ophardt, August 25, 2014

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