You could plant them all together or you could leave them until may and then plant the rest so you will have late spuds for the winter months..We have ours out now but will put in a late batch for the october....Hope you do well with your onions, ours came up last year, infact we had a good crop of veg...
Hope this helps.or you could try this link
I find this a good link to read for advise..
http://www.bbc.co.uk/gardening/htbg/...getables.shtml
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