How do I incorporate different flours into my sourdough starter?

Using a portion of mature basic wheat sour, you can change the flavors and textures by switching up the flours used for feeding. Most flours will be interchangeable at this point: white, whole wheat, durum wheat, spelt, Kamut®, etc. Alterations will need to be made when using rye and triticale flours, which contain more acetic acid than other flours (rye more so than triticale). To convert to a rye sour, follow the recipe below. The excess of acid in rye necessitates the addition of salt to slow down the fermentation process.

Mix water and sour until dissolved. Add the rye flour and mix very well; scrape down sides. Cover with cheesecloth or a clean towel and let sit at room temperature for 18–24 hours.