Between our (almost finished) porch & the driveway there is a sizable gap that I have been filling with flowers, shrubs, ornamental grasses, & even wormwood--despite all the strange looks & criticism when I mention the herb. However, there is still a lot of space. Bored, one day, I was browsing amazon.com for some inspiration on what I could fill in the gaps with. I came cross irish moss and creeping thyme. I am leaning more towards the irish moss. From pictures I have seen, I like how it looks, but I would you like some advice first before I buy anything. Is it easy to grow? Is it invasive--will it interfere with my other plants? Would it creep into my driveway (it's gravel)? Does it spread very fast? Any other topics I might need to know are welcome :)