Proper way to draw bar graphs with dates?

I'm a matplotlib newbie and I'm trying to figure out the proper way to draw a bar graph with dates along the x-axis. I am able to draw graph that properly uses dates with the plot_date() call and I can do a bar graph with bar(). I can even use the following code to get the output that I want:

plot_date(dates,units,visible = False)
bar(dates,units,width=5.0)
show()

but it seems to me that plotting and invisible plot_date graph is a bit clunky.

What is the proper way to do this with the library?

thanks,
John