A one foot, or more slope requires some specific landscape design, and maintenance planning. Fertilizer for instance, can be washed down a hill, making even distribution of necessary nutrients difficult. Mulching a steep slope is also an issue for a landscaper in Denver.
A landscaper in Denver may suggest that if re-grading is not an option, terraced planting beds could work well to create levels of varied greenery, and blossoms for a descending effect.
Ground covers are another good choice. There are many types to pick from, both foliage, and flowering