Onions are a cold season crop, easy to grow because of their hardiness. We recommend using onion sets, which can be planted without worry of frost damage and have a higher success rate than direct seed or transplants. Onions are a basic and essential ingredient in many meals.
Propagation
Onions can be grown from seed or sets (small bulbs). Sets are more costly but they are quick, reliable and a good choice for beginners.
Dig small holes, put sets into it exposing tips on the ground. You can lay a piece of string on the soil as a guide to make sure you dig the row in a straight line. Gently firm down the soil around the tips with your fingers. The sets should be planted with the tips pointing upwards and positioned about 10 cm apart. Each row should be 20-30 cm apart.
Onion seeds are short-lived. If planting seeds indoors, start with fresh seeds each year. Start seeds indoors about 6 weeks before transplanting. Move transplants into the garden as soon as the ground can be worked.
Soil
Avoid heavier soils such as clay and silt loams unless modified with organic matter to improve aeration and drainage. Onions are sensitive to highly acid soils and grow best when the pH is between 6.2 and 6.8.
Sun / Temperature
Onions grow best in full sun, so be careful not to plant the them in a location which will be shaded by taller vegetable plants. The onion is adapted to a wide range of temperatures and is frost-tolerant. For best production cool temperatures (55 F to 75 degrees F) prevailed over an extended period of time is required, permitting considerable foliage and root development before bulbing starts. A constant supply of adequate moisture is necessary for best results.
Watering
Generally, onions do not need consistent watering if mulch is used. If you want sweeter onions, water more.Onions will look healthy even if they are bone dry, be sure to water during drought condition.
Fertilizer
Fertilizers of a 1-2-2 ratio (5-10-10, for example) are good for onion production. As the onion plant's root system is very limited, high soil fertility is essential for good production.
Harvesting
Harvest green onions when the green stems reach about 6-8 in height. Scratch away the mounded soil around the stem base, grasp stem near the base and pull the green onion straight up. Lay the onions on top of the garden soil for a couple of days to dry out, then gather them up for storage preparation.