Tartan flat cap? Should it be armigerous? And maybe have a dandelion in it?

Regarding tartan/Argyle hose: The above-mentioned advice about dominant colors and such is what's usually seen, and hose worked in blue, green and red would go with several different tartans, including my Lockhart. You might consider, just for contrast, that the diamonds be worked in red and white, with blue or green stripes. That would contrast very nicely, I think, but still contain the tartan colors.
Please post pics when you decide what to do. I'm going to make myself some tartan hose one of these days.