title: Rotate subplot xaxis location
body: <p>I have two subplots on one figure.  Im plotting time (00:12:32) on the x-axis and I would like to rotate the xticks of both subplots but when I use the code below, only the one subplots ticks are rotated.</p>
  
  <pre><code>plt.xticks(rotation=90)
  </code></pre>
  
  <p>Here is the full code:</p>
  
  <pre><code>#print(start_event_arr)
  fig = plt.figure(figsize=(20.0, 20.0))
  fig1 = plt.figure(figsize=(20.0, 20.0))
  
  ax = fig.add_subplot(2,1,2)
  ax1 = fig1.add_subplot(2,1,1,sharex=ax)
  plt.setp(ax.get_xticklabels(), fontsize=6)
  
  
  dates = [dateutil.parser.parse(s) for s in start_event_arr]
  y = event_volume_sums
  #plt.xticks(rotation=90)
  
  ax.set_xticks(dates)
  ax.plot(dates, cumulative_vol_arr)
  ax.xaxis.set_major_formatter(mdates.DateFormatter('%H:%M:%S'))
  ax.xaxis.set_major_locator(mdates.MinuteLocator(interval=30))
  ax.tick_params(axis='x', which='major', labelsize=10)
  plt.xticks(rotation=90)
  
  cm = plt.cm.get_cmap('jet')
  ax1.scatter(dates,y,s=event_duration_secs*500, c=event_duration_secs,cmap=cm,linewidth=0,alpha=1.0)
  ax1.grid()
  
  #plt.setp(ax1.get_xticklabels(), visible=False)
  plt.show()
  </code></pre>
  
  <p>I suspects the problem is how i define the subplots but I dont know how to fix it. saying ax.xticks() isnt possible.
  Thank you.</p>