Allium cepa, commonly known as onion, is a controlled crop conventionally produced in Namibia during the cooler months of the year. 

At present, onions are produced across all seven production zones of Namibia at varying scales, with some farmers producing at a small scale for their own consumption and others producing at a commercial scale for markets. 

Onions are a common ingredient in many household dishes. 

Therefore, growing them ensures a market for the producer. 

This article aims to provide farmers with a basic understanding of how to cultivate this crop for optimal results.

The first and most important factor in onion production is the soil in which onions are grown. Onions can be produced in a variety of soils, but loamy soils typically yield the best results. 

The ideal soil for onion cultivation should be well-drained, well-aerated, and have a pH of 5.5 to 6.5. Additionally, temperature plays a crucial role.

 The ideal temperature range for onion production is 18-22 oC.

A critical factor that many farmers overlook is the ideal sowing time for onion seeds, as well as the methods used to sow them. 

The most common periods for sowing onion seeds are towards the end of March or early April. 

When it comes to seed sowing methods, onions can be sown either directly into production seed beds or in seedling trays for later transplantation into those beds. 

Onion seeds are small, so the recommended sowing depth is 1-2 cm in both seedling trays and seed beds.

Furthermore, onions should be grown according to spacing recommendations. 

The spacing between rows should be at least 15 cm, whilst the spacing within rows should be at least 7 cm. 

It is worth noting that these specifications can vary depending on the onion variety one intends to plant. 

In addition, the growing period can range from 90 to 200 days, depending on the variety. 

Varieties such as Texas Grano onion typically have a maturity period of 90 to 110 days from transplanting, though some sources cite 115 to 240 days, depending on the region and whether they are grown from seed or sets.

During the soil preparation stage, farmers should apply manure and incorporate it into the soil. 

To this end, it is vital for farmers to test their soil to determine the available nutrient reserves. 

Based on soil analysis results, a fertilisation programme can be developed and followed throughout the growing season. 

For example, NPK (2:3:2 or 2:3:4) is widely used in many onion production operations over the growing period. 

Another vital aspect to consider when growing onions is the crop’s water requirements during the growing period. 

On average, onions require between 400 and 600 mm of water over the entire growing period. Therefore, the irrigation system a farmer uses should be able to supply 400-600 mm of moisture to each onion plant over its growing period.

Lastly, when growing onions, it is important to consider the potential yield. 

In Namibia, the average yield for a 1 Ha operation typically ranges from 30 to 40 tonnes (30 000 to 40 000 kg) if spacing recommendations, irrigation practices, fertiliser application, and sowing depth are followed correctly. 

In well-managed operations, farmers can achieve yields of about 60 tonnes (60 000 kg) per hectare, making onion production a worthwhile venture.

*Hanks Saisai is Agribank’s technical advisor on crops and poultry.