If you wish to make anything grow, you must understand it, and understand it in a very real sense. 'Green fingers' are a fact, and a mystery only to the unpracticed. But green fingers are the extensions of a verdant heart.
What combines geometry and art and is alive? Knot gardens! The Old Farmer's Almanac explains that "a knot garden is artfully laid out and planned in order to resemble the threads of ancient Celtic knot work." They have their origins in Elizabethan England, four hundred+ years ago. I think some of these gardens are actually parterres, but I am not totally clear on the difference.
The Knot Garden at Hatfield House
photo by Jason Ballard
photo by Thomas Stanbury
Knot Garden Lollipops
photo by Jennifer de Graaf
Barockgarten Villandry in Frankreich
The Open University Knot Garden
photo by Double Down
The Knot garden at Lyme Park
photo by elleneka102
How to Plant a Herbal Knot Garden from WikiHow