Milk kefir grains can be cultured in coconut milk for those that want to avoid dairy products.
Kefir grains cannot be used to ferment milk replacements other than dairy milk perpetually. Their community of microorganisms is dependent on dairy milk and does not find all the nutrients it needs in milk replacements. If kefir grains are fed these alternatives over and over, the grains will eventually loose their vigour and might die. An occasional feeding with dairy milk is all that is needed to restore the microbial balance the grains need to thrive.
If using store-bought coconut milk, remember to avoid brands with additives, preservatives and sweeteners, as they can be hard on the kefir grains and even kill them.
Use coconut milk and not cream as cream is too thick.
Add 1-2 tsp milk kefir grains (you can get them here) (rinsed in unchlorinated water) to 1-2 cups coconut milk. Leave at room temperature to ferment for 12-24 hours away from direct sunlight. The time depends on the temperature in your home. The best rate is achieved at 22 - 25 C. Less temperature, means slower fermentation and it therefore takes more time.
Cover the glass jar loosely with a lid to avoid flies getting in.
After 12 hours, begin checking the coconut milk kefir every few hours, up to a maximum of 24 hours. Remove the milk kefir grains once the coconut kefir reaches the desired consistency. The finished coconut kefir can be stored in the fridge for up to one week and the grains can be used to ferment coconut milk again.
Sometimes kefir grains will require an adjustment period, so the first batch of coconut milk kefir may not culture as desired. Use the coconut milk from this batch for cooking and place the milk kefir grains in fresh coconut milk.
An adjustment period isn't uncommon whenever kefir grains are switched from one type of milk to another (cow to goat, pasteurized to raw, dairy to coconut, etc.).
You have to revitalize the grains in dairy milk for 24 hours once every few batches (aroud 3-4). Without that they will deteriorate.