African women attending to their onion crop
How to grow onions in Africa

The problem with growing onions in Africa, is that they tend to produce little green plants with no bulbs. This is absolutely down to a combination of a harsh climate and shorter day lengths compared to its native habitat of Iran and central Asia. Although it is perfectly reasonable to say that the onion has evolved to cope with warm, dry environments, the high levels of heat, and light experienced in central African countries are far greater than this crop can be expected to cope with. This is why onion crops struggle to produce decent bulbs here.

Be that as it may, if you can find suitable onion seed and are prepared to make the effort to make your local environment more comparable to onion production, then why shouldn't you be able grow onions in Africa

Onions being harvested in Africa
How to grow onions in Africa
I have come up with some solutions regarding, but be aware that the increased cost of producing onions using these solutions may end up being more that the actual value of the crop.

In Nigeria you have the problem with excessive rain. Of course, you can provide protection against the rain by planting your onions under cover. A simple frame protected by some a clear covering of plastic will do the trick, but you will need to provide adequate ventilation so that you don't end up 'boiling your crop.

Be aware that you will need a cover that won't break down under ultra-violet radiation. You can reduce the effect of this damage by re-enforcing any areas of the plastic that are resting on supports with a heavy duty tape.

Of course, once your crop is covered, your onions will still need to be watered especially during the growing season. Then, once your onions have stopped growing then they will need to be able to dry out for harvesting otherwise they will rot off.

If you can provide shade during the hottest part of the day, the risk of boiling your plants will be reduced.

Add automatic shade screens, additional lighting and better
ventilation and you could have the perfect
 conditions to growing onions in Africa!
Also, be aware that when onions get too hot their growth will become checked. Furthermore, if the onion plant is losing more water through transpiration than it can physically draw up through the roots then they can shut down and begin to dry out no matter how much you water you put on it.

Any hotter and you are at risk of losing the crop. You can try planting your onions through white plastic material  - called a plastic mulch - as this will help to reduce the amount that the soil will heat up by reflecting heat from the sun back into the air.

A simple solution to reducing the heat on the onion crop is to use lengths of shading material. This does mean physically putting it in place and then removing it later on a daily basis as your onion crop will actually benefit from the less intense morning and evening light levels and so may not be very practicable. Alternatively, plant in your crop where mid-day shade already exists or plant some suitable trees in the appropriate position.

Regarding the high levels of rainfall, protecting the crops from the rain isn't going to work if the the water table is so high that the ground becomes waterlogged no matter what you do. If this is the case then growing your onions in raised beds 6-12 inches high should do the trick. You can also consider growing your crop on a slope or digging out drainage gullies around the crop to help remove the run-off.

It goes without saying that your onion beds need to be kept weed free.

Bagging up onions in Africa
Bagging up onions for market
Onions are very sensitive to daylength. The kind of onion that is grown in the higher European latitudes
requires long day length to form bulbs.

When onions are grown during short days - as they are in equatorial Africa- it is important to plant what are called 'short day onions'. Most onions grown in the tropics are of the short-day type, but many different kinds of short day onions exist.

All onions are physiologically ‘long-day’ plants, but the mechanism that controls onion bulbing is really a phytochemical response to the length of the night. Therefore, in the so-called ‘short-day’ onions that are grown in the tropics, bulbing is in fact induced in response to night lengths, which are relatively long, at around 12 hours. Intermediate-day and long-day cultivars grown at higher latitudes are induced to form bulbs by nights that are relatively shorter - ie. nights of 11-8 hours, corresponding to days of 13-16 hours.

If you grow long day onions near the equator they grow into small green onions which may thicken a little at the base. This can be preferable because the short day varieties can form bulbs too soon.

So how do you overcome this? Providing additional lighting at the end of the day is clearly the key to getting around the short day issue. Light bulbs with a wave length as similar to natural day length are best, but if resources are limited then try using fluorescent tubes. My guess is that you will need an additional 2-3 hours of light extra each day, but this is something that you will need to find out through trial and error.

Growing onions from onion sets

Onion set ready for planting
Onion set ready for planting
Many growers in the tropics use onion set system to get onions going near the end of the rainy season in order to extend the onion harvest forward in time and therefore produce a larger bulb. Onion sets are commercially available in Zimbabwe.

However, the quality of onions grown from sets can be inferior, producing more double bulbs.

If you want to grow your own onion sets, try this method. Just as the hot season is starting, sow seeds at a very close spacing. Do not thin out the onions. Harvest at ½ inch (1.25 cm) diameter or else they will bolt. If they are sufficiently crowded and if it is well past the day length where the variety would normally bulb, they will die down naturally.

It may take a few seasons of trial to find out what works best for you.

For related article click onto the following links?
Growing Garlic in Pots and Containers
Growing onions in Africa

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