Window box suggestions...?

I want to plant window boxes for my house's basements windows. In the summer, the rec room is where we retreat and we like to have the cool breeze come through the windows in the evenings but we also live where it rains quite a bit and the mud from the ground splashes up onto the ledge and into the house.





I figured a nice set of window boxes would help with a layer of mulch to keep the mud down, but am unsure as to what to put in the boxes. I was thinking of a long grass or a long leafy plant like a spider plant. The coldest it gets is -10C and the area gets moderate light 9 mos a year and direct sunlight during summer. I also want to put in some shorter tulip variety or primrose in for colour.





I wanted to plant into the ground beside the house but the soil is only about 10" thick before hitting rock and we have a stone walkway 14" from the side of the house so it prohibits growth. We've tried before and had to move the plants to our back garden.





Any suggestions? Thanks!

Window box suggestions...?
Check out HGTV's web site. Also, Gardening by the Yard comes on HGTV on the weekends and they have a lot of segments on them.





Here are some links.