Fabric Requirements

If you are making the whole quilt you may want to buy all of your background fabric first.  The finished quilt is square, 6 x 6 blocks and each block is finished at 12 inches.  If you make the larger central block the finished size is still the same;  the large block replaces the 4 centre blocks.
The standard width of cotton fabric is 44 inches : 112cm.  You can cut 3 - 14 inch backing squares across the width of the fabric.  I cut my fabric in 14 inch lengths and cross cut 3 squares.  That makes a block bigger than you need, but if your applique is off centre than you can square it up before the blocks are assembled.
You need 12 widths for 36 blocks.  Cutting at 14 inches requires 168 inches : 4  2/3 yards : 4.3 metres.  Cutting at 13 inches requires 156 inches : 4 1/3 yards : 4 metres*

* That doesn't leave any room for error - better get 4.5 yards or 4.2 metres *

This is my first reproduction quilt so my stash isn't very big (yet).  I always wash my fabrics; many quilters don't.  I have used white quilters' muslin for my background (quilters' calico in the USA).  I want my finished quilt to look as if it was new so I'm using white and strong reds and greens.  You may want an aged look and use off-white with soft greens and pinks. 

You don't have to use one fabric for all of the background.  You may choose to use a selection of shirting prints and make the appliques in blues and reds and browns.  You may dig into your stash and use whatever you have on hand.  You may only make a nine block lap quilt with pieced sashing; just over a yard of background fabric would be enough.