This chalk work on the backs of the chairs was done last, in preparation for tomorrow.

Never use one just one set of complements for all your darks, it doesn't happen that way.
Use the opposition of the local color you want to darken. Here are some examples.
The orange's and sienna's are darkened with or washed with cobalt blue.
The greens are made dark with magenta.
The closer the green is to yellow, orange or red, the more ultramarine blue, cobalt blue or cyan is added to the magenta opposition making it darker.
That would be the normal sun lit shadow color of any local color green foreground object. This can be done with any color on the Real Color Wheel.