National Trust staff abseil down the 50 metre (160ft) high walls of the 12th century castle, on an island 300m off the south Cornish coast, in order to weed the granite stone three times a year.
The gardening work is needed to keep the walls clear of unwanted vegetation and allow succulent plants planted within the walls to flourish.
And the only way the four-strong team of gardeners at the medieval church and castle, which is cared for by the National Trust and the St Aubyn family who donated it to the Trust in 1954, can carry it out is by abseiling from the castle walls.
Lottie Allen, head gardener, said: “Abseiling has become an important skill to complete essential strimming and planting of the many nooks and crannies within the cliff face where plants grow in spite of the salty winter storms and baking summer temperatures.
“We weed these areas three times a year not only to ensure the stonework remains intact and strong but also to allow the succulents planted within the walls, such as Aloes and Aeoniums, to thrive and flourish.
“It is a thrilling and unique experience to tend these gardens which are designed to be viewed from above. On a personal note, abseiling allows me to appreciate the spectacular views of our gardens across the seasons and in all weathers.”
In early 2015, the team will be heading down the walls again to plant a large shelf-like area with succulents such as Agaves and Aeoniums, as well as Osteospermum and Agapanthus and pruning a large Puya, a member of the pineapple family.