Here's a sample of how I might do this. Note that I'm using some randomly generated numbers. The 5th column is integers.
I define a colormap of light green to dark green (credit to this page for getting me started), as well as red. By using the ColorLimit name-value pair, I can force any value greater than 1 to be red.
This was more guess and check than actual reasoning, so no guarantees it will work in all scenarios. However, it should be close enough to give you some ideas.
CV = reshape([rand(28,1); randi(15,7,1)],7,5)
gr = [linspace(.75,0,10)' ones(10,1) linspace(.75,0,10)';...
zeros(10,1) linspace(1,.5,10)' zeros(10,1)];
red = [1 0 0];
cmap = [gr; red];