Last year I grew a lot of sweetcorn plants together which I had started at
different times in modules. What I found was that for some reason the plants
all tried to produce kernels at the same time. Presumably the pollen or
something sets them all off. So the less developed sweetcorn didn't have a
good chance to make kernels and in the worst case there were some very
useless cobs with only one or two seeds on them.

This year I'm going to grow different varieties for different ripening times
again. My question is how far do I need to separate the corn plantings of
different things to get them not to interfere with each other's development
like this. Any suggestions?