Excessive transplanting will set them back.

If they're too small for you to feel comfortable at this point, let them grow on in this pot a while until they're bigger. Give them a couple of light doses of some kind of liquid fertilizer, good sunlight, and they'll size up pretty fast.

When you plant them out, I would say ideal spacing is about six to eight inches apart, if you have the luxury of that much room, but 4 inches will work in a pinch.

(Denninmi's advice)

They actually grew through the winter and are now big clumps themselves which I will thin this week. They are pretty foolproof, it seems.
Good Luck!

The white part (blanched) is what's underground. That's why you use a trench and fill in. It increases the useful part of the plant.

Mine self-sow and I get a whole new batch the next year!