If you are looking for an easy way to add color and a vertical effect in your garden, look to the grasses. For all their beauty, and that is considerable, I can't think of a plant that requires less from the gardener.
Grasses are very undemanding, low maintenance and easy to cultivate.
Just dig a hole, plant and water for the first month and leave them alone. Water weekly for the first month. Once established, they won't usually require any additional water. When you leave the foliage over winter, you provide a haven for birds and other critters and you can enjoy the sort of sculptural beauty of the various seed heads. The range of choices is incredible.