In my experience as a strictly home gardener, five feet is as close as I will go. Mind you, mine are planted in framed raised beds. I may have as many as five plantings in a 3' x 8' frame or as many as eight in a 3' x 14' frame.

I also wonder about the after effects of a companion that is not friendly towards the next years rotation. Then there are the marigolds that are said to be a preparatory planting for the following year. What about the addition of these same plants to the compost; not a serious concern.

Ahhh heck, I plant marigolds and herbs all through the plot of 2500 sq ft. I do not plant where known to be advesary.

I mix and match but try to place at least one bed between the poor companions. So far I have not seen detriment. All seem to grow very well with few pests, even in the traps.

Good companion planting.