I have not made any serious efforts to cultivate moss, but I do have plenty in various shady parts of our yard including an area at the edge of my artificial stream just below a water fall. The falls create a little splash, some of which reaches the moss area and I assume keeps it happy. I would therefore suggest that some gentle splash or mist would be useful. I would warn however that a porch pond sounds small and you would certainly need to take care to maintain pond levels so the pump doesn't run dry.

Is your moss a thick moss with dark green foliage or the thinner yellow/green variety? I have the deep green thick moss in the rooting bed and a lot of the flatter yellow green moss in the yard. I was going to try moving the lighter green and see if it would get more lush looking. I also have a few rocks with moss growing on them around another pond that stay green because of the splashing that I plan to relocate. I hope others will weigh in on this. I can see what I want in my head but would like a little more direction. I can gather some other mosses from the woods around us to try out. I know some need decayed wood instead of soil to grow on.

As long as the area gets little or no sun and you keep it moist, the moss should thrive. Here where it rains 8-9 months of the year we have no shortage of moss, but in August with 6-8 weeks of sun the moss in the open areas will start to dry out and look dead. It does come back in the fall. My small pond has a 12 volt solar panel, the pump can't handle much lift, but I have the panel placed in the full sun and it works well at about 8" above the water level. . .except when there is no sun, of course.

Under the porch on the north side of the house. Might get a little sun first thing in the am. So it should be a good place for moss. Can't wait to start. need to go pick up some more rocks.

I love the idea, just have no practical experience to add. I'd like to hear (and see) how it turns out :-)