Square 50cm2 gardening doesn't have the same ring to it but I'm a girl from the metric generation.
Generally I grow 4 varieties from a specific crop group - but it depends on the size of the mature plant. For example rhubarb, squash and globe artichokes have their own 50cm2 square to themselves. For roots I grow 4 types of roots in a square, the radish square is 3 different types of radish and some turnips, the onions have a slightly different take as I grow a few carrots in between the onions to help beat the pests.
I think this method is more pleasing to the eye than rows, especially once the crops get established. It has a higgledy piggledy view to the on looker (perhaps because of the close planting) but once you get up close you can see how everything is in its own individual zone. It almost has a potager look about it.
Its easy to weed as well and as everything grows closely together you don't get so many - just a bit more weeding at the start while crops are establishing themselves.
Interestingly in the mollusc invasion we had which accompanied the intensely wet weather - I didn't notice so much damage in the area where the square foot gardening method really took off. It mainly took off with the plant groups heavily suited to our temperate climate.
The mediterranean types didn't develop and so the weeds have dominated there - I've also had the most slug and snail damage in these areas.
Another method I tried in my new garden was the 3 sisters method. I was growing squash at the base to suppress weeds and store moisture and these were grown at the foot of the beans. I also grew sunflowers for the beans to climb but whilst the sunflowers were establishing (or desperately trying to survive in our disappointing weather) my boyfriend built climbing frames for them. This was not the summer for trying such a thing. The squash didn't grow big enough to over shadow the weeds and the sunflowers I was using in place of sweetcorn just got nobbled by the voracious slugs.
On a happier note, the squash are finally starting to grow now and I see the promise of baby fruit on some so all my efforts and feeding are (fingers and toes crossed!) not lost on my pumpkins and winter squash - they may still have a chance.
Have you tried any new planting methods this season?