How bright or muted is the colors you are using? Is a neon green needed in the design or is it a pastel yellow that is found in a flowering vine?

A composition must be appear to be balanced for saturation in the design of these walls. Saturation achieves different effects like balance and harmony. Representation is not a picture. Graphical representation of saturation does not necessarily translate directly to an actual vegetated wall however, often representation is not a direct parallel to reality. Saturation is a component of color mixing and color balancing in conjunction with hue and value. All three must be observed to make a composition.

Remember that any hues can make a composition, but that the complementary sets often can begin to create harmony.

Saturation can also be considered the intensity of a hue when used in a composition. This purity of color is important to the overall composition of an image or representation. If the saturation of an image is not even, then the image will appear washed out or incomplete. This can occur in the opposite direction if an image is over-saturated. Therefore an image can achieve balance or harmony though even saturation.

If there are a great number of hues and the composition appears to be in balance it is from an even saturation and the color are of the same hue or family of analogous hues. The characteristics of color reviewed in the literature (hue, saturation, and Value) can be quantified and scaled, but solely quantifying color does not relate to an architect attempting to represent a space in a two or three dimensional manner.

I recommend finding color found in nature as these are often in composition and not over-saturated.