Onions

Require a deep, rich, heavy soil. Where the ground is notsuitable it should have had a good dressing of rotten manure the
previous autumn, and left in ridges during the winter. Level the
ground, and make it very firm just before the time of sowing. The seed
should be sown early in March for the main crop and for salad and
pickling Onions, and in August for summer use. Thin out to about 6
in. apart, excepting those intended to be gathered while small. The
Tripoli varieties attain a large size if transplanted in the spring.
The Silver-skins do best on a poor soil. For exhibition Onions sow in
boxes early in February in a greenhouse; when about 1 in. high prick
out, 3 in. apart, into other boxes; give gentle heat and plenty of
air, and when they have grown 6 in. high put them in a cool frame
until the middle of April, when they must be planted in the open, 1
ft. apart.