How to plant and grow onion sets

Posted in All Gardening Advice, Vegetables and Fruit, March, on

Sets are easy to grow, with a small set turning into a full-sized bulb without any attention from you during the summer. Sets are the immature plants that are raised from seed the previous summer.  Because they were sown at a very high density, they do not reach sufficient size to bolt. They just carry on growing instead.

How and when to plant onion sets

Plant sets in early to mid-spring, pushing them gently into the soil so the tips are level with the surface. It’s a good idea to cover them with pea sticks or fleece to prevent birds pulling them out.
 
For lots of small bulbs about 5cm (2in) in diameter, plant the sets 2.5cm (1in) apart in rows 15cm (6in) apart. For larger bulbs 10cm (4in) across, widen the spacing of sets to 10cm (4in).
 
What type of soil should onions grow in
 
The chance of bolting is decreased if you avoid planting in cold, wet soil. They thrive in a sunny, well-drained situation. Keep weed-free, especially early on. It is important to move the onion bed around every year to prevent the build-up of diseases like onion white rot.
 
How to harvest onions
 
Harvest mid-summer. The foliage will yellow and fall over naturally. Lift the bulbs with a fork to break the roots and leave them on the soil surface to ripen fully in the sun.  In a wet summer, move them to a greenhouse bench to ripen.