plt.rcParams['hatch.color'] = 'b'
plt.plot([0, 1], [0, 1], ls='--', c='b')
plt.fill_between([0, 1], [0, 1], color='none', hatch='X', edgecolor='b',
    linewidth=0.0)
plt.show()
How do I fill a region with only hatch (no background colour) in matplotlib 2.0