I started planting a bunch of "hearts and flowers" but because of the full sun, and the winds, the water dries out pretty fast. The only thing I have found to water the hillside was an impact sprinkler on a tripod (HD) and because of the wind, even that ends up watering my neighbors yard rather than mine. (I am going to try soaker hoses soon).

Being concerned with the erosion, is the main reason for planting the H&F. I also planted a couple of plumeria on the hill because couple people told me it has a pretty good root system.

Any ideas for any other deep root groundcovers/plants/trees to hold the soil? Any slope watering ideas?

Almost any tree would stabalize your slope.

let me know if you want more suggestion. You can google any of these plants to see what they look like and growing requirements.

Good Luck
Phil