At this time Farrer travelled widely in the mountains of Italy, France and Switzerland, walking and climbing with gardener friends, including fellow plantsman E.A.
Farrer was attracted by the horticultural possibilities of the introduction of new hardy rock plants to the British gardening public.
With this in mind, he founded the Craven Nursery in Clapham, which specialised in Asian alpines, an enterprise which foundered in the economic crisis of the 1920s.
These two years of exploring and plant collecting are described in Farrer's On the Eaves of the World (2 vols) (1917), and in the posthumous The Rainbow Bridge (1921).
I sat down to paint it (the most marvellous and impressive Rhododendron I've ever seen – a gigantic, excellent, with corrugated leaves and great white trumpets stained with yellow inside – a thing alone, by itself WELL worth all the journey up here and everything) and oddly enough I did not enjoy doing so at first... a first false start – a second, better, splashed and spoilt, then a mizzle, so that umbrella had to be screamed for and held up with one hand while I worked with the other.
Then flies and torment and finally a wild dust storm with rain and thunder came raging over so that everything had feverishly to be hauled indoors and the Rhododendron fell over and all the lights and lines etc.
Farrer's collecting trips are particularly interesting when viewed in the context of the global plant exchanges which occurred during British Imperial rule.
During this time crops and other plants were transplanted from then-native habitats to others throughout the Empire for a variety of economic, medical and scientific reasons.
"[3] Farrer brought back plants from Asia that could be grown in a naturalistic style – not just by the rich who could afford expensive hothouses and personal gardeners.
He was a devotee of the novels of Jane Austen and wrote for July 1917 issue of The Quarterly Review an article in celebration of the centenary of her birth.
He took as his companion the mill-owner Euan Hillhouse Methven Cox, who recorded the trip in Farrer's Last Journey, Upper Burma 1919–20 (1926).
Himalayan rhododendron, bamboo and other unusual plants such as Lonicera syringantha and Rodgersia aesculifolia can be seen among Farrer's Ingleborough display while in Clapham village itself Viburnum farreri and Potentilla fruticosa flourish.
In 2015 Historic England commissioned a measured survey and analytical assessment of the fabric, layout and history of Farrer's Clapham garden to inform the future repair and management of the site.