I live in Seattle and plan to make a concrete paver patio this weekend. Right now it gets full sun, eventually I will be putting up a sun shade and plants should make it fairly shady.

I would like to put sand between the pavers and have some kind of moss in between. It will be a high foot traffic area and I would like something that will stand up well to that, and stay green year round.

Doing some research I have found irish moss seeds, that say to plant in spring, then I found this "moss milkshake" method where you mix dried moss, buttermilk, etc spray it on and cross your fingers.

I am hoping for suggestions here. Is sand appropriate for in between the stones? What would grow the best/fastest in this situation and meet my needs? Are seeds best? Is the milkshake a real option? Would you suggest anything else? When can I plant? Is there anything I can start now or should I wait until spring?

I am calling on all of your moss knowledge and appreciative of any advice! :)