By Stellah Jepkosgei

Onion farming in Kenya is slowly gaining popularity simply because it is affordable to start and its returns are high. Onions can be grown in greenhouses and also in open gardens.

What you need to familiarize yourself with before embarking on onion farming would be the current prices, market availability and the variety to plant.

  1. Land preparation – land should be prepared at least one month before planting.
  2. Nursery – raised beds of 1.2m width and 3-4m long. Seedlings are ready to be transplanted 45-60 days after sowing.S
  3. Planting – you can grow onions using transplants, seeds or sets. Transplants are seedlings that are usually started in the nursery in the growing season. They usually form good bulbs within a short time of 60 days or less.

Sets are bulbs that are not yet mature from the previous season. They are easy to plant, harvest and are resistant to diseases.

Growing onions from seed offers one a wide variety of choice. They can be established directly from the main field or started in a nursery and later transplanted in the main field when seedlings are pencil thick at a spacing of 30cm by 10cm.

               Sets are planted at 2.5cm apart for green onions or 8-10cm apart for the bulbs.

               Fertilizer requirement of about 80kg/acre DSP transplanting. This is very important because onions are very sensitive to phosphorus deficiency. 121kg CAN applied when plants start growing after transplanting to encourage early vegetative growth applied in 2 splits.       

  • Watering/irrigation – very dry conditions causes bulbs to split so watering should be done weekly. You can use sprinklers, drip system or pipes to water your onions. A good time to do this is early in the morning or late in the evening. Avoid watering them from above especially in the evening as moisture settling on the leaves easily causes diseases. Watering should be stopped 2-3 weeks before harvesting to give the bulbs time to cure.
  • Weeding – this should be done regularly to remove weeds between and within rows. As bulbs form, avoid earthing up, otherwise moist conditions may encourage rotting of the bulbs.
  • Pest and disease control – the most common conditions that affect onions include blight, purple blotch, downy mildew, rust and fusarium rots. They are caused by a fungus and are more common during periods of high moisture. Blight appears as small white spots surrounded by a greenish halo. Purple blotch causes a purplish discoloration of leaves. Proper plant spacing helps increase air flow and reduces both blight and purple blotch.

Most common pests include thrips which are sucking pests that attack onions causing the leaves to turn grey. They are barely visible as tiny yellow or specks of about 1mm long. Use pyrethrin to control them; and leaf miners.

  • Harvesting – onions take 4-5 months to fully mature and ready for harvesting. When ready to harvest, the leaves will lose color, weaken at the top of the bulb and hang low. Let most of your onion tops fall over the rest of the tops. Don’t leave the bulbs in the ground for longer than 2 weeks after the tops die because they become open to organisms that cause rot in storage. Harvest on a sunny day for the roots to die and dry. After harvesting, bulbs should be cured before storage.
  • Ecological requirements – the land should be more or less flat and have access to irrigation water. The soil type should be light and well drained with a Ph of 6-6.8. onions grow best at altitudes below 1900m, 500-700mm rainfall,15-30 degrees centigrade temperature range.

Varieties commonly grown in Kenya include; Red creole which is the most preferred variety by the farmers, Red Pinoy F1 from Royal seeds, Bombay Red and Texas Early Grano.

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