Hooker and a sizeable party of local assistants departed for eastern Nepal on 27 October 1848. They travelled to Zongri, west over the spurs of Kangchenjunga, and north west along Nepal's passes into Tibet. In April 1849 he planned a longer expedition into Sikkim. Leaving on 3May, he travelled north west up the Lachen Valley to the Kongra Lama Pass and then to the Lachoong Pass. Campbell and Hooker were imprisoned by the Dewan of Sikkim as they travelled towards the Cho La in Tibet. A British team was sent to negotiate with the king of Sikkim. However, they were released without any bloodshed and Hooker returned to Darjeeling, where he spent January and February 1850 writing his journals, replacing specimens lost during his detention and planning a journey for his last year in India. According to an 1887 journal written by Indian administrator Richard Temple, many of the rhododendrons found in English gardens of the time were grown from seeds collected by Hooker in Sikkim.