Growing Onions from seed - Help!

Its kind of early for cucumbers even in UK, They need a warm soil and can rot . (When you plant em, companion plant radish among the cucumbers, this helps dive away the borers and such)

Onions like moist soils and whenever I grew them from seed , I always grew the seedlings until they were about an eigth of an inch in stem diameter and then Id wash them out of the planting flat and replant them in the garden. They will develop nice bulbs with thin stems that dont rot as easily as those grown from "sets". Alsthough sets are the most convenient and idiot proof . Some years onions just fail. Was it really cold and did you have many rosts when you planted. As I recall, most of S UK has a more moderate climate but you still get some frosts in early growing season

From what you have said I think it was a number of things - may have been too cold (tempremental British weather of late has been anywhere from frost to sunbathing weather!- rain today, now brightening up) too small (the width of the growh was only around 2mm) and nt enough roots. The spot I have planted them in is quite bright too, and it looks like many have now drooped and given up.

Some are still hanging on but are dried out at the top.

On the up side, the lone cucumber plant is still going, althoughthe 3 others have keeled over, so I will put all my energy into that and keep my fingers crossed!