A few people have told me that sweet chestnut lasts for years in the ground if you cut it green (which is why they say it’s good for fenceposts). But no one’s ever been able to tell me almost exactly how many years.
Instead, I had to find out for myself by conducting Quite A Long Experiment.
My experiment consisted of making this outdoor safari-style kitchen for écovallée, based on a drawing we saw in a book called “Living Wood” by Mike Abbott:
I cut the chestnut green and stuck it in the ground within minutes, ramming our clay-rich soil around it. Then I waited. (To add a bit of random interest, one of the ‘uprights’ was hornbeam.) The experiment began in April 2010.
Last year, I replaced a couple of the smaller cross pieces – one because it snapped and another because it was sagging. This year, I was going to replace the whole structure with acacia – a decision confirmed when some of the thinner, now-brittle parts succumbed to the ravages of wind, snow and time during the Winter.
A couple of days ago, I took the kitchen down (it was all lashed together, which worked well but needed re-doing from time to time) and I can now reveal the results of my experiment. Here are the buried ends of two chestnut ‘uprights’:
The wood at the ends is soft but not all the way through. The thinnest chestnut ‘upright’ did rot through completely. And the buried part of the hornbeam vanished into the ground.
So there you have it: Conclusive proof that, in our soil, green chestnut of around 8 cm diameter will be good for around 35 months.
If you find yourself talking fenceposts with someone later this year (and that’s not as unlikely as it might sound), when they say: “It lasts for years in the ground if you cut it green”, and someone else says “Yes, but how many?”, you can say “Just less than three – it really depends on your soil”.