How to determine the correct moment to harvest onions
The adequate moment to harvest onions is determined by the final destination of the onions. One of the main factors is the decision to store or not to store the onions. If the decision is to store, the onions have to mature completely in the field.
Table of Contents
1. Earlier Onion
- The Early Onion is harvested the moment the plants foilage starts toppling over.
- The onion bulb is inmature and the plants foilage has hardly toppled at all.
- This kind of early unripe onions are sold directly from the field (often called “Fresh Onions”) without any grading in simple mash bags for un-demanding low priced markets.
2. The Medium mature onions
- Medium mature onions are havested when 50 to 70% of the plant foilage has toppled over.
- The onion bulb is in the process of maturing and the harvesting is done with about 50 to 70% of the plants foliage toppled over. The bulb nearly has reached its physiological maturity.
- Sales are done after a superficial drying and curing and a possible grading to a market that appreciates (pays for) these treatments.
3. The mature Onions
- Mature and good quality onions.
- The onion bulb is physiological completely mature and the plants foliage has toppled over for at least 70%.
- Final destiny for these mature quality onions: 1. Sophisticated and demanding markets, 2. Export markets, 3. Storage for later sales.
The moment the onion stem topples over is very important.
From the moment the foliage starts toppling over the yield can still increase a 10 to 50%, this depends on the weather conditions. The temperature and light conditions should be moderate.
A late harvest signifies a higher yield and a better quality but also a greater risk for being susceptible at adverse climate conditions (like dew and rain). Remember the harvest time will be at the beginning of autumn or at the beginning of the rainy season. Rain and dew will produce black stains on the outer skin of the onion.
The reality, it is a form of art to determine when the onions are ready for harvesting, this requires a lot of experience and it also depends on the fact if the onions are going to be stored or not. Never forget that successful storage requires a very mature onion. The very important decision regarding to store or not to store will be discussed later on in this webpage.
With respect to determine the correct or adequate moment for harvesting we have to take into account the following considerations: During the last 3 to 4 weeks in the field the yield increases considerably, the possibilities to store the onions diminishes because of weather risks (humidity and rain). Taking all this into account the indicators that the onions are ready for harvesting are:
- Onions can be harvested when 50 to 80% of the foliage has toppled over and the plants have the neck of the stem soft and weak. Ideally would be when 90 to 100% had toppled over. This means that we have a window of opportunity of about 2 weeks to harvest the onions (between the phase with 50 to 80% toppled and 90 to 10% toppled). This is the time that the producer must be in the field watching his onions and the weather constantly.
- The ligaments of the onions start to change from light green to a darker color, brownish or purplish, which depends on the variety.
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