Onions are one of the most popular vegetables for growing in home gardens and are one of the first crops of spring. They can be stored over winter, thus making a versatile crop.
They are used in a huge range of culinary dishes, both raw and cooked.
Preparation
If adding manure or composted organic matter, then add a few weeks before sowing/planting out.
You can tread the soil gently to firm it up a bit before sowing.
Sowing
Onions can be planted from either seeds or sets (small, partially grown onion bulbs). While sets are typically more expensive, they are generally more reliable and require less effort. Sets eliminate the need for thinning and reduce the risk of onion fly infestation.
Sowing from Seed
If planting onions from seed, sow them in drills about 2cm deep, with roughly 1 inch (2.5cm) between seeds. For row planting, maintain about 30cm between rows to allow ample space for growth.
Ensure the soil is moist before sowing. It’s a good idea to check the soil the day before planting and water it if needed to maintain adequate moisture.
Planting Onion Sets
For onion sets, planting can typically begin around mid to late March, or earlier if you’re using a cloche or polytunnel for added warmth. Space rows about 30cm apart and position sets roughly 10cm apart. Dig a small hole for each set, placing them with the neck facing upward. After covering with soil, the tip of the neck should be just visible above the surface.
Sowing Spring Onions (Scallions)
Spring onions can be sown from April onward. For a continuous harvest throughout the growing season, stagger planting every few weeks to ensure a steady crop.
Position
Onions will grow in most climates and are frost resistant.
Soil type
Onions will grow in almost any soil from sandy loams to heavy clay. The soil should be firm. If your soil is heavy, then you can introduce some organic compost or manure into the soil to help its moisture retaining properties.
Onions prefer a slightly acidic soil – PH 5.5-6.5 is a good PH for growing onions.
Tending
Frequently weed between the onions by shallow hoeing, onions do not trap much incoming light due to their sparse leaf forms so weeds can take full advantage of the availalle light.
If your crop has been sown from seed, then you will need to thin the onions when they reach about 5 cm in height. Thin them so that they are spaced about 10cm apart.
Harvesting
Onions are ready to harvest a week after their tops have started to fall over and are yellowed.
Use a fork to lift the onions out of the ground. Take care not to damage the skins as this invites decay organisms to attack the onion flesh.
Onions should be harvested on a sunny day, cleaned of any soil still attached to them and then placed on top of the soil where they will dry out with the help of the sun and wind.. Leave the onions out for a few days (until the tops dry out).
Remove the tops with a sharp knife about 2cm above the onion top so that decay organisms do not have direct access to the onion bulb.
Discard any onions that show signs of decay or damage as these can affect healthy onions if they are stored.
If you want to store the onions over winter, then you can cure them by hanging them in a well-ventilated place (such as from the roof of a summer house veranda). Mesh bags or strings can be used to group and hang the onions, and they should hang for about 3-4 weeks.
Spring onions can be harvested when they are about 30-40cm in height and will store for up to a week in the fridge. To prepare spring onions, simply remove the outer set of leaves and wash.
Diseases
Onion Fly is attracted by the smell that thinning the onions releases. For this reason the method of growing from sets rather than seed is advantageous when trying to combat onion fly. Onion blast – this fungus develops on the plants foliage with a blast of speed.
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