There are two major types of onions grown in the country, namely spring and bulb, with the latter having a longer shelf-life.
Onion farming in Kenya can be done in greenhouses and open gardens. The most commonly used onion is the bulb onion. It is locally consumed and available from roadside sellers to supermarkets.It can be grown by direct seeding, which requires intensive management or one can decide to first establish a nursery bed
Just like other vegetables planted on nursery bed, site selection is key to proper planning for production of healthy and vigorous growing seedlings. The site should be in a secure environment, near a water source and preferably near the crop production site.
Different Types of Onions
Onion is so widely used that any culinary dish from almost any part of the earth has the vegetable added to it. No doubt there are several types of onions – but here, we talk about the most common ones.
Yellow onions – They have ivory white flesh that is surrounded by heavy brown skin. They have a strong and sulfur-like aroma.
Sweet onions – They have a lighter, less-opaque skin that surrounds a larger and slightly fatter body of the vegetable.
White onions – They have a papery white skin, and they are milder and sweeter than their yellow counterparts.
Red onions – They are mild and sweet enough to be eaten raw. The exterior skin and flesh are a deep magenta.
Shallots – They are smaller and brown-skinned and have purple flesh.
Green onions – They are the immature onions that haven’t yet formed a bulb.
Leeks – They are shaped like overgrown scallions (the long-necked onion with a small bulb) and are usually used in sauces and soups.
Best Soil condition & Preparation for onion farming
Before planting onion you should learn about the best soil condition and other relevant factors which affect onion farming.
Red loam and sandy loam are highly preferable for onion farming.
No problem if you don’t have those types of a soil, you can improve your soil by using organic materials.
Onions are mostly grown in any soil but the soil should be loose, well-drained, and should have plenty of nitrogen.
The ideal range of soil pH for growing best onion is in between 5.5 and 6.5.
You can grow onions using transplants, seeds or sets. Transplants are seedlings that usually are started in the growing season; they usually form good bulbs within a short time 60 days or less. To get the best results with onions you need to start them in a Nursery. Here is how to do this;
- Make a raised nursery bed 1 metre wide and any desired length.
- Apply well decomposed manure at a rate of 15kg per square metre.
- Mix and Apply DAP fertilizer at a rate of 20 grams per metre square
- Make shallow furrows 15 cm apart. Mix the seeds with dry ash, sand or soil at a ratio of 1:3 to help spread the small seeds.
- Plant the seeds and cover lightly with soil and apply mulches ( Grass or Polythene cover spread over the soil on the nursery bed)
- After planting irrigate the nursery bed liberally for the first 10 days and continue watering regularly.
- Germination of seeds will take about 7-10 days after which the mulches are removed and used to make a shade above the tender plants which have not fully developed.
- Transplanting of the seedlings takes place 6 weeks after planting seeds in the nursery. Transplant when the seedlings have pencil thick base and a height of approximately 15cm.
- Seedlings should have 3 to 5 well-formed leaves at transplanting time. Two weeks before transplanting reduce the shade to improve seedling survival rate in the field.
- It takes about 4 months for onions to mature
Challenges facing Onion Farming in Kenya
Rains or Excess Watering: Too much rains or excess watering can water log the crop. If the rain in your area is too much, focus on growing the crop during the short rains. You can also raise the beds to ensure the water flows out of the field. Avoid excessive watering of your onions. The best type of irrigation on onions is drip irrigation. Overhead irrigation should be avoided as it causes fungal diseases.
Diseases: Common diseases that affect onions include Downy Mildew, Bacterial Soft Rots, Pink/White Root, Botrytis, and Rusts. Use herbicides to get rid of the diseases.
Pests: Common pests that attack onions include maggots, thrips, nematodes and the leaf miner. Use pesticides from accredited brands to get rid of the pests.
Weeds: Weeds can also destroy your crop and should be removed occasionally either physically or through the use of herbicides. In one season, there should be at least 2 – 3 weeding sessions.
Pest and Disease Controlling Methods of Onion farming
Onions are more sensitive to insects, weeds, and diseases than other vegetable crops. Every one generally expects a disease-and insect-free crop.
- But the maggots are the one possible pest of onion. It’s 1/3-inch-long white, legless worms that move in a line from one bulb to the next and make hole upwards to feed on the stems.
To overcome the excessive damage, scatter-plant onions throughout the field. It will discourage the adult flies from setting their eggs at the roots of the plants if you put a thin layer of sand around onion bulbs.
- There may be a chance to affect scarcely visible onion thrips during hot, dry weather. It causes damaged plants with shiny spots on the leaves.
Thrips in weeds. maintaining the garden clear helps you to reduce insect populations. Covering a studious mulch, such as aluminum flake, among rows may be the efficient way to deflect the thrips. The early you can discover that problem, you can spray your bulbs to combat thrips.
- A disorder called smut makes swelling up or hardening of leaves just about the neck, which ultimately blasts and drops dusty black spots over the plant. In the middle of the summer during warm, humid weather downy mildew, a purplish mold, shows up.
- Onions are moreover subject to pink root, it makes roots turn different colors and after that shrink, and neck spoilt, due to this reason tissues become hard and black crust.
All these issues are made by fungi in the soil and can be eliminated by rotating crops and by working humus within the onion bed to accommodate good drainage.
Usually, onions are harvested when the tops turn down and start to dry. Short day varieties, however, don’t mature uniformly so they are usually lifted when 50 per cent of the tops are down and have dried.
- Pull any onions that send up flower stalks; this means that the onions have stopped growing. These onions will not store well but can be used in recipes within a few days.
- When onions start to mature, the tops (foliage) become yellow and begin to fall over. At that point, bend the tops down or even stomp on them to speed the final ripening process.
- Loosen the soil around the bulbs to encourage drying.
- When tops are brown, pull the onions.
- Be sure to harvest in late summer, before cool weather. Mature onions may spoil in fall weather.
- Clip the roots and cut the tops back to 1 inch (but leave the tops on if you are planning to braid the onions).
- Let the onions cure on dry ground for a few days, weather permitting. Always handle them very carefully—the slightest bruise will encourage rot to set in.
- Allow onions to dry for several weeks before you store them in a root cellar or any other storage area. Spread them out on an open screen off the ground to dry.
- Store at 40 to 50°F (4 to 10°C) in braids or with the stems removed in a mesh bag or nylon stocking.
- Mature, dry-skinned bulbs like it cool and dry.
- A pungent onion will store longer than a sweet onion. Eat the sweet varieties first and save the more pungent onions for later.
Factors to consider before planting
- Market availability,
- Price of the onions
- Variety of the plant.