Pandas plot axvspan
<p>I have a dataframe like this</p>

<pre><code>from datetime import date
import random

start_date = date.today().replace(day=1, month=1).toordinal()
end_date = date.today().toordinal()

df=pd.DataFrame.from_dict({'dates':[ date.fromordinal(random.randint(start_date, end_date)) for i in xrange(10) ]
                        ,'n':np.random.randint(0,100,10)})
df.index=df['dates']; del df['dates']
df.sort_index(inplace=True)
</code></pre>

<p>Which generates</p>

<pre><code>             n
dates         
2016-01-24   0
2016-02-26  98
2016-03-04  68
2016-03-26  45
2016-05-03  89
2016-05-09  83
2016-05-11  58
2016-07-29  53
2016-09-18  79
2016-10-20  57
</code></pre>

<p>I would like to plot it and have a axvspan for February and March. Since my dates are random how can I select those 2 months and use axvspan</p>

<p>my plotting code is simple</p>

<pre><code>ax=df.plot()
</code></pre>