{"id":4490,"date":"2026-07-20T12:34:09","date_gmt":"2026-07-20T12:34:09","guid":{"rendered":"https:\/\/www.opapod.it\/onions-harvesting-curing-and-storage\/"},"modified":"2026-07-22T13:21:26","modified_gmt":"2026-07-22T13:21:26","slug":"onions-harvesting-curing-and-storage","status":"publish","type":"post","link":"https:\/\/www.opapod.it\/en\/onions-harvesting-curing-and-storage\/","title":{"rendered":"Onions: Harvesting, Curing and Storage"},"content":{"rendered":"\t\t
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When to harvest onions: look at the plant, not the bulb <\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The onion is a biennial plant grown as an annual crop<\/strong>. It is sown between autumn and spring<\/strong> and harvested in summer<\/strong>, generally from June to August.<\/strong><\/p>

The right time<\/strong> to harvest<\/strong> is determined by observing the stem, which turns yellow and begins to bend towards the ground.<\/strong><\/p>

Early varieties can be harvested once the bulbs have reached an acceptable diameter <\/strong>and the outer skins have dried sufficiently.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Two harvesting methods: traditional and direct harvesting<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tOnions can be harvested using two different methods, each of which has a direct impact on product quality during the subsequent handling and storage stages.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Traditional harvesting<\/h3>

The bulbs are mechanically lifted, arranged in windrows and left to cure in the field. \n
Curing takes place in the sun for a period that varies according to weather conditions and the variety. <\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Direct harvesting<\/h3>

In a single operation, the machine cuts the leaves 3\u201310 cm above the bulb, lifts the onions and transfers them into pallet boxes or trailers for immediate transport to the storage facility.
This method reduces handling time, increases storage capacity and improves air circulation inside the containers. <\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Onion storage: temperature, humidity and ventilation<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Once curing is complete, onions can be stored either at ambient temperature <\/strong>or in a cold-storage facility.<\/strong><\/p>

The most suitable option depends on the required storage period,<\/strong> the variety<\/strong> and the intended market.<\/strong><\/p>

In both cases, the three key parameters are:– temperature<\/strong>;– relative humidity;<\/strong>– ventilation<\/strong><\/p>

Managing these factors together is the key to extending shelf life.<\/strong><\/p>

The temperature should be kept either above 25\u00b0C<\/strong> or close to 0\u00b0C<\/strong>. Intermediate temperatures encourage sprouting, fungal growth<\/strong> and shrivelling<\/strong>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Storage at ambient temperature<\/h3>

Ambient storage preferably requires facilities equipped with forced ventilation systems<\/strong>, allowing temperature<\/strong> and relative humidity<\/strong> to be regulated.
\nWhite onion varieties must be stored in dark conditions<\/strong> to prevent greening. <\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Technical parameters for indoor curing<\/h4>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Airflow<\/p>

300 m\u00b3\/t\/h<\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Air temperature<\/p>

25-35\u00b0C<\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Relative humidity<\/p>

Below 75%<\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Post-harvest chemical treatments<\/p>

Not authorised<\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Cold storage<\/h3>

Cold storage helps preserve onion quality over an extended period.
Once thoroughly cured, the bulbs can be stored in pallet boxes or in bulk piles.
Bulk storage makes it possible to use the same facility for the final curing stage and provides more uniform ventilation.<\/strong>
This method allows onions to be stored for up to 4\u20138 months.<\/strong> <\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Technical parameters for cold storage<\/h4>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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temperature<\/p>

0\u00b0C<\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Relative humidity<\/p>

70-75%<\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Maximum storage period<\/p>

4\u20138 months, depending on the cultivar<\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Maximum bulk-pile height<\/p>

3 metres<\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Taking onions out of cold storage: key precautions<\/h3>

At the end of the storage period, the temperature must be raised gradually to prevent moisture from condensing on the bulbs.<\/strong>\nCondensation creates favourable conditions for pathogen development and root growth.
A gradual return to ambient temperature helps protect product quality<\/strong> until the onions are marketed.<\/p><\/div><\/div>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Transport: the final link in the quality chain<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Transport vehicles must be well ventilated<\/strong> to prevent moisture condensation. The onions must also be stacked in a way that ensures proper air circulation and load stability.<\/strong> For long-distance journeys, mixed loads should be avoide<\/strong>d. Volatile compounds released by onion bulbs may transfer unusual odours to other products transported in the same vehicle.<\/p>

During winter, protection against temperatures below the freezing point<\/strong> of onions, approximately \u22121\u00b0C, may be necessary on certain routes.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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The importance of logistics<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Efficient logistics management is essential for preserving the quality of the harvested crop.<\/p>

APOD members <\/strong>can rely on a dedicated service covering product collection, storage, sorting and transport <\/strong>through to final delivery, ensuring traceability, punctuality and the highest level of care at every handling stage.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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\n\t\t\t\t\t\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\tAPOD logistics service<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Pre-processing and grading: adding value before sale<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Before sale, the cured product should undergo careful<\/strong> pre-processing.<\/strong><\/p>

Sorting the bulbs into groups<\/strong> according to size makes it easier to organise both storage and marketing.<\/p>

This allows each batch to be removed from cold storage<\/strong> at the most suitable time, taking into account its specific characteristics and expected market prices.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Want to improve onion growing and post-harvest management? <\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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APOD supports its members throughout every stage of the supply chain, from technical advice in the field and post-harvest quality management to logistics.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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\n\t\t\t\t\t\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\tDiscover all APOD services<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Frequently Asked Questions About Onions<\/p>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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When are onions harvested? <\/div><\/span>\n\t\t\t\t\t\t\t\n\t\t\t<\/line><\/svg><\/span>\n\t\t\t<\/line><\/line><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tOnions are generally harvested between June and August, when the stems have turned yellow and begin to bend towards the ground.Early varieties may be harvested once the bulbs have reached a suitable diameter and the outer skins are well developed. \t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t
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How are onions cured after harvesting? <\/div><\/span>\n\t\t\t\t\t\t\t\n\t\t\t<\/line><\/svg><\/span>\n\t\t\t<\/line><\/line><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tOnions can be cured directly in the field by leaving the bulbs in windrows after lifting, or indoors in a storage facility with controlled ventilation.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t
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What is the ideal temperature for storing onions? <\/div><\/span>\n\t\t\t\t\t\t\t\n\t\t\t<\/line><\/svg><\/span>\n\t\t\t<\/line><\/line><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tFor long-term storage, onions should be kept at temperatures close to 0\u00b0C or above 25\u00b0C.Intermediate temperatures encourage sprouting, fungal disease development and quality loss. \t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t
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How long can onions be stored? <\/div><\/span>\n\t\t\t\t\t\t\t\n\t\t\t<\/line><\/svg><\/span>\n\t\t\t<\/line><\/line><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tWhen properly cured and kept in cold storage under controlled temperature, humidity and ventilation conditions, onions can retain their quality for up to 4\u20138 months, depending on the variety and storage conditions. \t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t
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How can onions be prevented from sprouting during storage? <\/div><\/span>\n\t\t\t\t\t\t\t\n\t\t\t<\/line><\/svg><\/span>\n\t\t\t<\/line><\/line><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tTo limit sprouting, it is essential to maintain a stable temperature, ensure adequate ventilation and control relative humidity.A gradual return to ambient temperature after cold storage also helps preserve bulb quality. \t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t