|Craigybarns, image available at redbubble|
And according to contemporary photos of the now-climbable cliff, they still are.
Inspiration for your spring planting from the famous engineer James Nasmyth (inventor of the steam hammer), who was writing about his father, Scottish landscape painter Alexander Nasmyth. The cannon-planting took place about 1788. Both Nasmyths were polymaths with wide interests. Alexander was considered the founder of Scottish landscape painting, but he was trained in architecture and dabbled in engineering and in the formation of actual landcapes, providing designs for the pump room that still stands over St. Bernard's well in the center of Edinburgh, a picturesque plan for the landscape at Inveraray (including a 'beehive cottage' for the gamekeeper), and advice for turning the ruined Colinton Castle into a folly.