I use whole wheat berries to start my sourdough and fresh berries are important. You can get them in any health foods or whole foods store or your local co op if you are so lucky.
In a glass 2 pint mason jar:
3½ tablespoons (1 ounce, 28.5 grams) any flour, any grind (100%). I use 50/50 white wheat then only wheat there after.
¼ cup (2 ounces, 56.5 grams) filtered or spring water, at room temperature (about 70°F/21°C) (200%)
Add a teaspoon of wheat berries , stir.
put on a loose fitting lid and put in warm area until it starts to bubble, stirring at least once everyday to aerate .
That is the seed culture. All the recipes i've read say toss half the seed and keep adding as above but Ill be hellandbound if I am going to toss out perfectly good food !
I Just continue to build this seed 3 times, and use that , skipping the mother starter usually and just use the fresh seed to start my dough.
Peter Reinhardt has pretty specific instructions and his are the books I own and use.
I highly recommend for reading anything by him.
I do have copy's that I can loan if anyone whats to read them.
zo0