AgEBB-MU CAFNR Extension

David Burton
Civic Communications Specialist
2400 S. Scenic Ave.
Springfield, MO 65807

May 25, 2018

Onions Bolting Early Can Cause Storage Problems

CARTHAGE, Mo. — Onion growers have noticed something unusual in their crop this year. Some of their onions are bolting early according to Robert Balek, horticulture specialist with University of Missouri Extension.

"Bolting is the process by which onions produce a flower stalk, resulting in seed production. Typically, onions do not bolt until their bulbs are fully developed, around late June for many varieties," said Balek.

According to Balek, the early bolting in May is due to the relatively cool spring weather in March and April.

"When the onion bolts early, the bulb stops growing and does not mature," said Balek.

There are two choices for growers when onions bolt early:

One, harvest the bulbs early.

"By harvesting bulbs as they bolt, growers can have a steady supply of fresh onions. However, onions that bolt early do not store well because they are not mature," said Balek. "These onions will keep for a week after harvest. These harvested bulbs can be stored longer if cut up and frozen for later use."

Two, delay harvesting until later by leaving them in the ground.

"Growers can cut off the flowers at the top of the stem, or cut the entire stem down near the bulb. Do not cut off the leaves. Removing the flowers will not restart bulb growth. Once the flowers are removed, early bolting onion bulbs will keep in the ground several weeks to be pulled and used later," said Balek.

For more information, contact one of MU Extension's horticulture specialists or educators in southwest Missouri: Patrick Byers in Webster County at (417) 859-2044, Kelly McGowan in Greene County at (417) 881-8909 or Robert Balek in Jasper County at (417) 358-2158. Or, call the gardening hotline operated by the Master Gardeners of Greene County at 417-874-2963.

Source: Robert Balek, 417-358-2158

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