We inherited a flagstone patio when we bought our house last year. It is in a shady area right next to the house. The spaces between the flagstones are quite large–a couple of inches in many places–and are filled with compacted clay soil. They basically just get muddy and grow weeds. Because it’s so shady (an hour or less of sun per day, and we have a table and chairs on the patio creating more shade), I haven’t found any great ideas for groundcover/moss to grow. I did experiment with some irish moss last year, which is still alive, but it hasn’t spread much and unless it starts spreading more quickly, I probably can’t afford to buy enough to fill in all the spaces. So: any advice about what I should use to fill those spaces? Some kind of moss or groundcover? Pebbles? Stone dust?