When can I plant the rest of my onion sets?

[elemental]

I've got loads of onion sets left over from when I planted in March. I was going to save them to next spring (not sure if they wont have started to sprout by then though) but if I can plant them early for next year that would be even better.  

Whats the earliest I can plant them for next year?

Could I still plant some this week to be ready for eating autumn (maybe not for storing).

[elemental]

[john_miller]

Onion sets are especially conditioned to provide useable starters for planting. It is unlikely that they will store until next year.
The varieties that are used for sets are short day varieties- they produce bulbs in response to shortening daylength. If they have not been able to produce a large root system or sufficent leaves before these conditions exist (with 'maincrop' potatoes it is when daylength decreases to 14 hours, probably similarly with onions) then it is unlikely a worthwhile bulb will be produced. You are too late to get a crop now. The best you can hope for is some green onions/spring onions/scallions (I'm too tired to remember what they are called in the U.K., sorry).

[elemental]

ah at last, wouldn't let me reply yesterday, kept logging me out!

Thanks John for your reply - its all making more sense to me now!
:)
What I'm going to do is plant the remainder of the sets this weekend coming and use them as 'spring onions' in Septemeber/October. The ones I planted in March I'll let them go the full course and store them for use over winter.Of those that have started to go to seed, I will use them and keep a couple to produce seed (my neighbour at the lottie told me I will have to use them quick otherwise they will go hard/dry as they put all their energy into the seed head).

When will I be able to sow the seeds and do I need a greenhouse (I dont fancy having my window sills taken for the WHOLE of the winter as well as the summer!). I've heard it can be tricky?

Where would I be without this site!!!!