Azaleas ground layer super easily, and naturally (to the point of being pesky). I've ground layered as many as 8 one-gallon pots at a time off of a three-gallon donor azalea using a technique that I found in a book or magazine, before the days of internet.
Imagine a configuration like a daisy, where the three-gallon is the center and the one-gallon pots are the petals. In the shade of pines, I broke each branch to be layered where it was half intact/half splintered and inserted it into an overfilled one-gallon pot, with the broken branch poised as upright as possible. Thoroughly filled the one-gallon pot with dirt (shoveled out of the surrounding ground), covered the dirt with pine straw to preserve moisture, set a brick on the branch in the one-gallon pot to hold it in place, and after initially watering, pretty much ignored it for a few months. Fertilized it a time or two, but other than that, almost no attention. From the spring to the fall, I was able to parlay 4 three-gallon azaleas about 25 lush landscape-worthy plants. The one-gallon pots were completely filled with roots, and some had grown through the bottom into the ground. Didn't use any hormones. My entire point is that they are crazy easy to ground layer.