Dig It! Box Hedges (30 Oct 2017)
Box plants have had a hard few years and lots of people are looking for alternatives, one of the most popular is Ilex crenata "Dark Green" and this is what the grand baroque garden of Het Loo in the Netherlands chose to replace their 27km of box hedging!
Over the last few weeks, I’ve been visiting some new gardens, both public and private and heard a tale of woe about the owners’ box wood plants. Box or Buxus sempervirens, has been used for centuries in formal gardens for edging paths, clipping into shapes like balls or cones, and generally lending an air of dignity and permanence to even the newest of plantings. Unfortunately, box in Switzerland has been attacked by a new pest, the box tree caterpillar (pyrale du buis in French and the Buchsbaumzunzler in German) Cydalima perspectalis. It originated in Asia and has been making its’ way steadily across Europe for the last few years. The plants can be stripped of leaves in a matter of days by the green and black caterpillars. They have few natural predators, so their numbers are not reduced significantly, although blue tits and some other birds are starting to eat them. The caterpillars hide inside the plant with their 1200 brothers and sisters, away from human eyes and the reach of most insecticides. Once the caterpillars have become moths and flown away, the plants can grow back, but with more than one generation of the caterpillars per year, the repeated dattakcs are exhausting for the plant. Once the plant is at this stage, it is more likely to succumb to one of the two box diseases. Box blight and Volutella blight are quite common here, and although it is possible to treat both diseases with a fungicide, the weakened plant may not recover.
Many gardens with a great deal of box are wondering what they can plant instead. Earlier this year, I
visited the Dutch baroque masterpiece that is Het Loo and I spoke to Willem Zielemann, the head gardener about their 27 km of box hedges, their struggles with box blight, and what they chose to do instead. After a disastrous 2008 when the entire garden flooded, spreading the spores of box blight across the entire garden, they decided to take out the box completely and replace it with Ilex crenata “Dark Green.”
Their learnings were that Ilex crenata “Dark Green” can make an excellent replacement for box if you can provide good drainage and a soil with an acidic pH. If this doesn’t match your garden situation, don’t worry, there are lots of other alternatives to box that might fit the bill, and we will take a look at those next week on Dig It. Willem will also be back in a few weeks talking about the magnificent garden at Het Loo.