In the assemblies of the enlightened ones there have been many cases of mastering
the Way bringing forth the heart of plants and trees; this is what awakening the mind
for enlightenment is like. The fifth patriarch of Zen was once a pine-planting wayfarer;
Rinzai worked on planting cedars and pines on Mount Obaku. ... Working with
plants, trees, fences and walls, if they practice sincerely they will attain enlightenment.

~ Dogen Zenji,
Awakening the Unsurpassed Mind