Sweetcorn between the potatoes??

That was an interesting exchange of ideas.
I'm not sure that I have enough space to grow the corn in its own bed so I am looking at the shallots. There's always a plan B.
I have 6 rows across the allotment and they should be harvested in June.  By sowing corn in May and growing the plants in pots (supermarket cut flower pots)  it should be possible to have the exchange in place by early July.
I will have plenty of compost and rotted horse manure by then to dig in so does anyone have any thoughts on this idea. Thank you once again.

Sounds a bit risky to me Ivor.

Even if your shallots are ready in late June you would still be losing at least a few weeks of valuable growing time for the sweetcorn which need as much "quality time" in the ground as possible.

Your local conditions may well be different, but it wouldn't work for me simply because my shallots have never been ready before about mid-July. 

Thank you JayG. I have just checked last year's diary and I lifted my shallots in late July. I am giving up cellery and swede so I will have to reorganised the beds, to make room.

I do not know, how it is on your location exactly, but here, winter brassica, winter onions, early pots, early brassica and sometimes garlic are all up by July. If that is the time you want to plant there. We do June here.