Sweetcorn

This has been very helpful. I was considering 2 varieties this year. I’m sticking to one after this information.

You can grow two if they're the same type. Discovering the types of each seed can be problematic, the seed merchants don't always specify.
I'd go with Earlibird for the big one. I've never bothered with a small one, too much faff for not a lot of return. By all means sow early if you think you can get away without frosting. I sow early May, you may get away with late April. Plant in blocks rather than rows (as if!) so they pollinate each other.
Have a look here https://gardenfocused.co.uk/vegetable/sw...ieties.php for some basic info. It looks like Earlibird and Goldcrest are the same type so might not need isolating from each other. I'd grow in blocks of 3x3 or 4x4 depending on how many you're planning to grow. I usually try to do 2 blocks of 5x5 or 6x6 staggering the sow dates but have found thy catch up with each other.

I sow in root trainers to allow long root growth like you would sweet peas. Hen they can be transplanted with minimal root disturbance. I'm told sweetcorn don't like root disturbance but once when someone gave me a pot crammed with 8" tall sweetcorn plants, I separated them and they grew on ok.

Going to ask a really basic question now. How close together can you grow in blocks?

You can grow two if they're the same type.  Discovering the types of each seed can be problematic, the seed merchants don't always specify.

This is the main issue, I think. All sweetcorn varieties should be clearly labelled as su/se/sh2/syn, and all seed sellers should have a little infographic showing which types can be grown next to each other. 

Then you have a variety like Swift which is variously described by seed sellers as 'extra tender', 'tendersweet' or 'extra tendersweet', which is overly confusing since it's still sh2, just more tender aka 'augmented sh2'.

Thanks JJB. More to consider!
The truth is - I'm not that keen on sweetcorn so have only ever grown it because I had the seeds! A kind of bung 'em in and hope for the best seed! I do, however, like the mini-corn for use in stirfries but I can see that they are a faff when you really want a big cob.
Time for a story!! We were in New York State at the time of 9/11, on a walking holiday and staying at a converted Shaker Mill in the middle of nowhere, until we were able to go to New York for our flight home. One evening, a local farmer came to visit, bringing with him a large suitcase packed with all sorts of sweetcorn that he grew on his farm. They were all sizes and colours and he told us all about their different merits and uses. We ate so much sweetcorn that night I think I was corned out for life!

Thanks JJB. More to consider!
The truth is - I'm not that keen on sweetcorn so have only ever grown it because I had the seeds! A kind of bung 'em in and hope for the best seed! I do, however, like the mini-corn for use in stirfries but I can see that they are a faff when you really want a big cob.
Time for a story!! We were in New York State at the time of 9/11, on a walking holiday and staying at a converted Shaker Mill in the middle of nowhere, until we were able to go to New York for our flight home. One evening, a local farmer came to visit, bringing with him a large suitcase packed with all sorts of sweetcorn that he grew on his farm. They were all sizes and colours and he told us all about their different merits and uses. We ate so much sweetcorn that night I think I was  corned out for life!

Can't have too much sweetcorn, along with butter of course   if you do grow it successfully, like carrots, the homegrown has a far superior taste than shop bought.

Going to ask a really basic question now. How close together can you grow in blocks?

15 - 18"  / 35 - 45 cm each way. But depending on space I'd go with what fits. If your planning on 3 sisters planting  give them more room for interplanting.

Has anyone tried gowing corn the way the native Americans do? Dig holes eight inches deep and put 8 - 10 seeds per hole, then thin to four or five when they come up. Probably too deep for our generally wetter soils, the depth is for protection in desert conditions I believe, but growing them in a clump seems a grassy thing to do, and it is a grass, albeit a big 'un.

I haven't tried that method Moth, but sounds interesting. They would definitely pollinate that way, wouldn't they?

I might try that for those I direct sow later in the year!

I've never heard of that method Moth. I think a bit of research is in order.