Use a ratio of 1:100, i.e. 100 grams per liter. I'd make a 1.5-2 liter starter. Less than that, and you don't get a whole lot of propagation.
The Fiesty(sic) Goat Brewery est. 2007 & Clusterfuggle Experimental Ales est. 2009
Planned: sLambic II, Flanders Red II
Primary: Fat Man Porter, Orange Blossom Mead, sLambic I
Secondary: Flanders Red I
Kegged: 3 different ciders, Janet's Brown, Barrel-aged Stout, Hallertau Blanc Pale Ale
Bottled: Flanders Red I