The sample quilt layouts shown below using the Cactus Plant quilt block are featured using only shades of green as a colour palette. I was going with the colour of the actual cactus plants. However, many real life cactus plants feature lots of interesting flowers in a variety of colours, so you might want to make your quilts a more colourful variation, rather than use the monochromatic tone of these quilts. Ah, the beauty of quilting -- you make all the choices to fashion it as your own.