Mining plant phenology records from Kanazawa, Japan in the 1807–1838 Kakuson Diary

Mining the various records of plant phenology before the era of modern weather observations is an important but challenging task. We mined descriptions of plant phenology in Kanazawa, Japan, during the first half of the nineteenth century in the Kakuson Diary. We retrieved records of full bloom of 28 plant species, appearance of 31 seasonal foods, and peak leaf colouring. In particular, we found more than 10 years of records of plum, peach, cherry blossoms, udo, and bamboo shoots in spring; watermelon in summer; and persimmon, chestnut, and peak leaf colouring in autumn. The records suggest that spring phenology during 1807 to 1838 was later and autumn phenology was earlier than now. Despite spatio-temporal uncertainty in records in old diaries, we need to mine records of plant phenology in more old diaries and publish them in English.