Problem with the x-axis

[Mark17]

I'm trying to plot five price subplots in a 2x3 grid:

import pandas as pd
import matplotlib.pyplot as plt
import datetime

rawdate_start = '2007-01-01' #input('Please enter start date as YYYY-MM-DD: ')
rawdate_end = '2019-01-01' #input('Please enter end date as YYYY-MM-DD: ')
markets = ['ES', 'GC', 'CL', 'EC', 'US']
plt.figure(facecolor='lightgrey')
subplot_count = 1
for market in markets:
    columnname_0 = market+'_Close'
    columnname_1 = market+'_Daily_Rtn'
    columnname_2 = market+'_Cum_Rtn'
    columnname_3 = market+'_Value'
    market = pd.read_csv(r'C:\Users\drkle\{}(daily).csv'.format(market), parse_dates=["Date"], index_col="Date")
    market_cut = market.drop(['Open','High','Low','Vol','OI'],axis=1)
    market_cut = market_cut[rawdate_start:rawdate_end]
    market_cut.columns = [columnname_0]
    plt.subplot(3,2,subplot_count)
    plt.plot(columnname_0)
    subplot_count += 1
plt.show()

I thought matplotlib was supposed to recognize this as a datetime index (from Line 15) and print dates accordingly (from Lines 5, 6, 17) so they are legible. I'm getting five empty subplots with x-axis tick values from -0.05 to +0.05 (increments of 0.25). Why no dates? Thanks!