In my understanding, you would like to have date formatted tick labels for axes when using 'pcolor'. You cannot directly provide 'pcolor' with datetime vectors as of now.
However, there is a way to use the ' datenum ' and ' datetick ' functions to get datetime axes tick labels as illustrated in the example below:
%Creating two example vectors of datetimes, tx and ty
t1 = datetime(2017,9,2,0,0,0);
t2 = datetime(2017,9,30,0,0,0);
tx = t1:5:t2;
ty = tx + day(15);
%Creating an example C matrix for pcolor plot
C = magic(length(tx));
% Using datenum to convert to real numbers for plotting and dateticks for
% date labelling. You can play around with datetick options to suit your needs
pcolor(datenum(tx), datenum(ty), C);
datetick('y', 'dd-mm-yy', 'keepticks');
datetick('x', 'dd-mm-yy', 'keepticks');
I hope this accomplishes what you would like to do.