[PipKelpy]

I do understand crop rotation, (might not completely follow it though).

Right, in my thinking, my spud bed this year, I was thinking next year's onions (won't over winter again, been a disaster, again!)

But, does rotation include "inbetween?"

Rather leave that bed empty all winter (or covered in black plastic) could I shove brassicas in it? I know you might shout out lettuces but we don't actually eat lettuce (or much salad) in winter, unless you count an iceberg from Aldi once a month!

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I have read somewhere that someone grows field beans as he loves them but that's not us, runner, french, broad yes and saying that broad beans at the right size straight out of the garden with new spuds and fried bacon, yum yum.
I grew up with Mum, which meant cardboard and string (biggest broad beans she could grow as there were 5 of us, meaning they were tough and chewy and dry and runner beans that were only top and tailed to save wastage. To this day my 2nd eldest sister 53 years young, REFUSES to eat broad or string beans! I grow stringless yet peel the sides "just in case!" )

[Penninehillbilly]

I use a 4yr rotation, spuds, followed by legumes and onions (different beds), then there are roots and brassicas, but tbh, it depends which books you read, I once read spuds should be followed by brassicas, because brassicas need lime and spuds don't like lime, followed by legumes, which also like lime, and manure, many brassicas would be cropped over winter, brussels, cabbage, and seems debatable whether swede comes under brassicas or roots.
Depending on where you are, maybe just time to get swede and kale on the go, and I've just started some chard off, sprouting the seed inside to speed things up, just about to put some swede seedlings out. Maybe time for carrots in a sheltered spot? According to seed packet, beetroot can be down in July, so I've planted some out recently, got another tray for polytunnel.
I don't have much luck with overseeing onions either! 

[cloddopper]

I feel that crop rotation is exactly than not yearly crops in a bed .
In selected beds  I tend to manure heavily in late autumn  & grow greedy crops like beans , cabbages , cauli or  leeks  followed by salad stuff & annual, herbs then to something that is not so hungry in nutrients then after that garlics & onions  in the bed  and the following crop if it is still warm enough is carrots galore in the same bed sown through a plastic mask that gives 16 carrots per square foot .

This tends to result in a three or four year rotation of well manured beds ,  the high nitrogen is usually spent by the time the carrots are grown as a result  I rarely get forked root crops with this method

 I do keep records on paper ..the old neck top computer is too fallible