Instead of writing about a particular plant or plant group, this week I thought I would talk about one of my favorite horticultural pruning techniques. The first time someone mentioned to me an “aerial hedge,” I envisioned puffy clouds of boxwoods floating through the air. But that would be weird and strange (like this week’s episode of Mad Men – yes, I am a big fan). Then, on a trip to Hampton Court, I saw a screen made from a quadruple cordon of hornbeam trees. A cordon is literally “cable” or “line” in French. It is also a horticultural term for a horizontal line of a topiary. As for these trees at Hampton Court, the hornbeam trees were growing out of a hedgerow of Taxus. The hornbeams were trained into four cordons and then tied together to make a big screen around the parking lot. It was beautiful and precise. Right then and there, I fell in love with the concept.
Years later, on a visit to France, a group of us visited Versailles. It was there that I saw miles of trees pruned into hedges. In some spots, the trees were limbed up from the ground so you could see across the plane but the tree canopies were pruned into long rectangles. Aha! This was the infamous aerial hedge. If you look at the competition gardens at the Chelsea flower show, one designer always goes for the aerial hedge. Maybe it is a European thing (like the man-purse) but aerial hedges never seem to catch on here in the US. I, for one, really dig aerial hedges (and messenger bags but not man-purses) and wish that more gardens would include them. Yes, they take time and someone has to work for years to prune and shape them but the resulting form is fun and really defines a garden. I can count on one hand, the gardens that I have seen in the United States that feature aerial hedges:
– Longwood Gardens (Tilia or little leaf linden)
– Dumbarton Oaks (Carpinus or hornbeam)
– Old Westbury (Tsuga or hemlock)
– Lotusland (Pittosporum)
– Heronswood (a really awesome, arching display of trained hornbeams)
There have to be other gardens that I have missed. Are there aerial hedges that you recall seeing here in the States? Why do you think that they have not caught on here as they have in Europe? If ever given the chance to design a Chelsea garden, I would design a satirical garden featuring an assortment of aerial hedges using plants that one would never expect to see grown this way.