Python - Multiple frames with Grid manager

After messing around with my code for a few hours, I was finally able to create the GUI that I intended to. The key was looping over rows and columns and setting their weights using rowconfigure and columnconfigure, respectively. Code is below:

from tkinter import *

class Application(Frame):
    def __init__(self, master=None):
        Frame.__init__(self, master)
        self.grid()
        self.master.title("Grid Manager")

        for r in range(6):
            self.master.rowconfigure(r, weight=1)    
        for c in range(5):
            self.master.columnconfigure(c, weight=1)
            Button(master, text="Button {0}".format(c)).grid(row=6,column=c,sticky=E+W)

        Frame1 = Frame(master, bg="red")
        Frame1.grid(row = 0, column = 0, rowspan = 3, columnspan = 2, sticky = W+E+N+S) 
        Frame2 = Frame(master, bg="blue")
        Frame2.grid(row = 3, column = 0, rowspan = 3, columnspan = 2, sticky = W+E+N+S)
        Frame3 = Frame(master, bg="green")
        Frame3.grid(row = 0, column = 2, rowspan = 6, columnspan = 3, sticky = W+E+N+S)

root = Tk()
root.geometry("400x200+200+200")
app = Application(master=root)
app.mainloop()

Since frame 1, 2 and 3 don't have any widgets inside them and you haven't given them any height, their natural size will be one pixel tall. If you put something in frame2, or give frame2 a height, it will show up.