From the brewery:

This beer was brewed with wheat, fermented and conditioned with a mixed culture of yeast and bacteria, and then aged in oak barrels for one year. It was then refermented with delicious Rhubarb from nearby Primrose Vale, for 4 weeks. This is a beautiful balanced, nuanced and complex beer – rustic, earthy with a jammy rhubarb flavour and gentle acidity – superb!