Onion is a cool-season crop that is heavily dependent on day length for bulb production. In South Africa, the dividing line for onions is an imaginary line running horizontally through Bloemfontein. Above this line is considered a short day-length planting area and below the line is an intermediate day-length planting area. In South Africa, we do not have a long day-length planting area.
Typically, onions are planted in late summer to early autumn. Ensure that you have fresh seed, as onion seed expires and will not germinate if older than 2 years. You can start them off as sets and transplant into the beds or you can sow directly. Onions harvested from transplanted sets generally do not store as well as straight-grown bulbs.
Harvest once the tops fall over. Pushing the tops over to get them to dry up does not create a good storage onion.