

Since I don't know what area of the country you live in it is difficult to make suggestions for the types of planting that would work. A larger bed would also allow you to plant in front of the ac unit to help reduce the impact on the landscape. I think you need a mixture of evergreen and deciduous shrubs to create the bones that will carry the plantings all year long.

Medium shrubs with their foundations hidden by smaller plantings along the edge of the plant bed where you can enjoy the colors and contrast. I would make the plant bed edge in line with the post or in line with the edge of the patio to give you enough room to do a layered planting. By sloping from the foundation out to the edge of a plant bed, drainage can be set in the plant bed edge to collect any water. It is important to get the slope so that water flows away from the foundation. These can have vines grown on them or be left blank as a simple geometric form against the wall. I often use simple vertical and horizontal lath screens hung on the side of blank walls to help break up the sterile wall. You could plant between the patio and ac unit screen. I also suggest a small screen on the side of the ac unit to hide it. Adding a small bench along the side of the patio between the post and house (one without a back), will help the useful space and increase the feeling of making the patio a room. You could also wrap the steps around the lower level to tie the patio into the sides and back of the yard. There is enough depth between the lower level to the upper level to simply pour concrete over the existing lower level and form in two steps at the edge. You can add two steps to the lower lawn area for access and also increase the size of the useable patio by doing this. I would first suggest adding concrete, pavers or stone over the lower level to bring the total patio to one level. The monotone of the concrete makes it difficult to see and it breaks up your patio into two unusable spaces. This is a real ankle breaker and single steps like this are the number one reason for injury in landscapes. The first concern I see is the dangerous single step in the middle of your patio.

Hi There, I am a landscape architect in the Pacific Northwest that specializes in residential design that can be done in stages to meet schedule and budget.
