What Are Onion Sets & How To Plant Them

Planting Onion Sets

Growing your own onions is not difficult, especially from onion sets. The variety available to the gardener is so much more expansive than shop-bought varieties. 

Onions can be grown from seed or from onion sets which are a small onion bulb. Onion sets are an easy way to start growing your own onions, so, what are they and how do you plant them?

What Are Onion Sets?

Planting Onion Sets

Onion sets are small bulbs that are grown from seed the previous year. Sets can be planted in the spring and then will form a bulb quickly in the same year so you can harvest your own onions pretty quickly.

Pretty much all garden centres and even supermarkets now sell onion sets, offering a wide range of varieties

The onion set is a small bulb around 1/2 inch / 1.3cm which is basically an immature onion. The beauty of using sets is that the time from planting to harvest is much shorter than from seed.

When To Buy & Plant Onion Sets

Onion sets are usually available to buy from early spring and because they give you an effective head start to growing from seed they can be planted from spring onwards as soon as the soil can be worked. 

Certain varieties of onion are sold to be overwintered from autumn onwards. These are usually varieties that take longer to mature and need the extra time in the ground. When you come to buying onion sets it is a good idea to check the time to harvest to ensure your growing season will be long enough.

How To Plant Onion Sets

Onion sets grow well in most soil conditions but the soil does need to be well worked so that the bulbs aren’t constricted too much when they form. 

Planting sets is one of the easiest jobs in the garden. I would recommend using a plank or a string line to mark a row.

Onion Set Spacing

Make a hole with your finger every 10 – 12cm / 4 – 5 inches and then push the onion set into the hole with the shoot end pointed upwards. They need to be around 5cm / 2 inches deep.

Keep rows of onions around 30cm / 1 foot apart and keep weeds at bay as they will overtake the delicate leaves of the onions quite quickly.

How Long Will Onion Sets Take To Reach Harvest?

Harvesting Onions

As sets have a considerable headstart over seed-grown onions you can expect to harvest spring-planted onions in around late summer. 

The way to check if onions are ready to harvest is to look at the foliage. The onion leaves should have yellowed and started to fall over.

You may choose to lift the onions and use immediately or to store the onions as they store really well.

Harvesting Onions To Store

To harvest onion you want to store wait until the foliage has completely died back, you want to harvest them when the weather is dry and sunny. Lift the onions without breaking off the roots or bending the leaves over.

Place the onions on racks in full sun and make sure there is plenty of ventilation for a week or two. Once the skins have gone dry and papery the onions can be stored in a cool, dark and dry place. The top foliage can be trimmed down but leave some attached.

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