Onion sets are immature onion bulbs specially grown for planting out. When planted in the soil they increase in size and form one full-sized onion, which can then be harvested.
Gardeners prefer to grow sets, rather than onion seeds, because sets are:
* quick maturing
* less prone to disease
* able to grow in a rougher seedbed
* happy in most sorts of soil
* more suitable for later springs in the North
But, sets used to have a tendency to ‘bolt’.
Bolting means they go to seed, that is, instead of producing a nice big onion, they put all their energy into producing a seed head.
Modern sets are heat treated to destroy the internal flower bud, & stop bolting.
TO PLANT ONION SETS:
* Prepare the bed by digging over & raking flat. Mix some well rotted compost, farm yard manure or general fertiliser, into the seedbed.
* Place the measuring stick on the row, and plant the sets every 10cm, leaving 23 cm between the rows
* Push the sets into the soft earth, & bring the earth back around them, leaving just the tip showing
* Watch for birds, as they like to pull the tips, so that the sets are pulled out of the ground. If the birds start to do this, cover the sets with netting, string or cotton, to keep the birds off until the sets have grown good roots. Gently press the onion sets down for the first few weeks after planting, in case they have been disturbed.