what plants for long thin boxes on rooftop?
Hi! New here. We have a rooftop deck in Cleveland, Ohio and we have some planter boxes Im struggling to know what to do with. I have a few of these boxes and their dimensions are about 9" tall, by 6" wide by 5' long. We're told we need to consider anything we put in them annuals because the soil will freeze in the winter due to the small size (no way to bring them in). Our aesthetic is pretty modern and we love grasses. We're not to big on actual flowers. But everything I see at the stores basically fill up the height and width of the box immediately. Can I count on plants to send their roots out sideways? Anything with height and colored leaves is preferred. Oh and anything we put in them has to be absolutely cat safe in case of nibbling. Watering daily is not a problem.
Appreciate any thoughts!