plot_date - extra values added that are not in my data


I have been wrestling with matplotlib all evening (im completely new
to it since a few hours ago) and finally almost have my graph

There is just one thing left that I can't seem to figure out myself.
I have attached the graph for reference (hope attachments are

It is a date plot, my data starts at 16:58:11 and ends at 17:25:14 but
for some reason I am being given ticks for a few minutes before and a
few minutes after.

Is there some kind of compress, or trim function that I can use to get
rid of these and have the axis start at my first data point and end at
my last. Or at least the nearest major tick?