Kombucha needs Camellia sinensis to be properly nourished.
That means black, green, white, and/or oolong teas. Flavored teas, such as Earl Gray, Red Zinger or Chai, often contain antipbacterial essential oils that may damage the kombucha culture, so avoid using them for your main brew. Strongly smokey teas such as Lapsang Souchong, while they won’t technically damage the culture, are not considered a good flavor match by most brewers.
SCOBYs grow baby SCOBYs.
In the past, I’ve puréed the extras in water and fed them to the garden. But I just tried brewing a batch of kombucha with herbal teas. It’s so delicious!
Herbal teas do not nourish the SCOBY properly; they may also contaminate the kombucha culture with wild yeasts. So it’s a bad idea to mix an herbal SCOBY or herbal kombucha tea with your main batch.
However, since I was chucking my extra SCOBYs in the garden anyway, I think that, from now on, I will use them first to brew an herbal batch and THEN I’ll purée them for the garden.
Here are a few tips from the ‘net about brewing herbal kombucha.
Teas with a high amounts of volatile oils are not recommended for brewing kombucha, because the oils kill some of the beneficial bacteria in the culture. Oily herbs include sage, peppermint, St. John’s wort, chamomile, ginger, or plants within the pepper family.
Medicinal herbs can greatly enhance the beneficial properties of the kombucha. E.g., aniseed, young blackberry or raspberry leaf and berry, chicory root, club moss, dandelion, elder flowers and berries, fennel, hibiscus flower, nettle leaf, oat straw, rooibos tea (aka, red bush tea), plantain leaf, rose hips common, yerba maté leaf, and valerian root.