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Growing Onions in Queensland

Introducing Onions

This well know vegetable is a staple in most kitchens. Its surprisingly easy to grow at home. Onions need a long, cool growing season to establish themselves and then warm weather for the bulbs to mature in summer. Onions are classified by colour and also by how many hours of daylight they need. Be sure to plant a variety that grows well in your area. In Queensland, short day varieties, also known as early or midseason varieties do best.

Classic Mistakes

Onions must be planted from seed, seedlings or sets. Planting an onion that has started sprouting in your kitchen is a great way to grow green onions or onion seed, but you won’t get any onion bulbs from it.

Sunlight

Grow in: Full Sun

Soil Preparation

Work some lime into your soil, as onions prefer a slight alkaline soil. Grow them in a bed where some heavy feeders were grown previously. Onions don’t like too much nitrogen, but they do like a soil that is full of organic matter, so work in lots of compost before planting.

Sowing Seed

Sow seed: March-June
Sowing depth: Sprinkle seeds gently onto the soil and cover lightly.

Sow seeds every 4 weeks to prolong the harvest.

Different varieties may have slightly different planting times depending on their daylight requirements and whether they are early or late varieties. Check the seed packet before planting to see when specific varieties need to be planted.

Sprinkle seeds gently onto the soil and cover lightly. Once they are established, they will need to be thinned according to the spacing guidelines found on the seed packet. Alternatively, let them grow a little bigger before thinning and then used the plants you remove as spring onions.

Planting

Plant seedlings: April-August

Try to plant bought seedlings as soon as possible after you get them home and remember to give them a good, deep watering to help them settle in. When you plant your seedlings out, add a small amount of organic bone-meal to each hole. Bone-meal gives seedlings a great start and helps them to develop strong root systems which support a healthy plant. Don’t worry if your seedlings look a little sad and flop over after being planted out. Just keep them well watered and they’ll be standing up happily in a day or two.

Care

Weed well between the onions. They don't like to compete for food and water.

Watering

When the seedlings are young, water regularly. Once they start nearing maturity, allow the soil to dry out between watering sessions. Your onions should reach this stage at some point in spring or summer (depending on the variety and when they were planted). At this point, the rains should be starting to let up, which will make it easier to control how much water they receive.

Feeding

You don’t want to overfeed onions. Too much nitrogen will cause them to have lovely big leaves and underdeveloped root bulbs. Feed every three months with an organic low-nitrogen fertilizer.

Mulching

Don’t mulch onions. Towards the end of their growing season, the soil needs to be allowed to dry out or they may rot.

Harvesting

Harvest: 25 to 34 Weeks After Planting

Onions can be harvested as soon as they reach a size you’re happy with. You will know your onions are ready to be harvested for storage when the leaves dry out and fall over. Gently dig the bulbs up and remove them from the soil. Leave them in a sunny, well-ventilated spot to cure for up to two weeks. You’ll know they’re finished curing once the skin is papery, and the roots and leaves are dry. Once they are cured, brush the dirt off them and remove the dead stems, leaves and roots. Alternatively, keep the leaves on and plait them to hang for storage. Onions should be stored in a cool, dry, well ventilated spot and kept away from direct sunlight. Don’t store any onions that are damaged or mouldy, rather use them up first before they spoil.

What to do about Downy mildew?

Pale leaf tips with grey mould which can turn yellow and purple is Downy Mildew. Burn all affected plants immediately.

What to do about Powdery Mildew?

Milk spray or baking soda solution work well and can be sprayed on affected plants.
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