I got a really cheap deal on a stir plate one day and have used it for many starters. It works like a champ and definitely hits the cell growth mark every time (knock wood). After some research into it, it looks like it’s one of the most reliable and easy to use tools for creating a good starter.
White Labs have run some tests using a stir plate and found that almost in every instance it provides 2 to 3 times the cell growth of non stirred starter. Another good thing about it is I need to use an Erlenmeyer Flask, which I can add the DME, water and nutrients right into and boil on my flame top stove (I’ve heard coil burners are more tricky and you should do a slow step up of heat on those if your’e going to boil in the flask).
Some things to keep in mind is that your stir plate could add up to 5 degrees of heat to your starter. So make sure you monitor temps. Additionally due to the constant stirring it’s easier for the air temperature fluctuations to change your starter. So try to put it in a place where temps are stable, like a closet or fermentation chamber.
Build your own