I am reliably informed by a quick Google search that St Catherine's day is the 25th November. According to the French, it's a good day for transplanting plants:
A la Sainte Catherine,
Tout bois prend racine.
That is, everything tree-like takes root (if transplanted) on St Catherine's day. I take this to mean that generally, Autumn is a good time for transplanting things, and there is a certain logic to this. The cool, damp weather means that plants don't lose much water through whatever leaves they have remaining, and the roots, being in soil that can be expected to stay moist until early Summer, has time to recover from the shock of transplantation.
I'm starting a bit early this year, but I'm hoping that Madame Catherine won't be too angry with me. The hazelnut trees in my garden drop their nuts everywhere and even the industrious squirrels can't prevent the occasional ones from germinating into trees where I don't want them. It seems a waste of a good tree just to dig them up and put them on the compost heap, so I transplant them to the field opposite, where I hope they will form the foundations of a little coppice. I loosen the soil around the roots with a pick-axe, and then pull the tree out, trying to keep as much root with it as I can. I transport them in the barrow over to the field, keeping the roots covered with soil so even the finest ones don't dry out.
I've tried a number of methods to get hazelnuts to grow there. I started one year by sticking new-growth twigs into the ground, hoping they would root: a complete failure. I spent ages one year planting a nut every six inches or so, again with no success. The only thing that has worked is transplanting young trees and even that hasn't worked 100%. Out of last year's plantings of maybe 12 trees, four are still live. But still, that's better than any other method I've tried.
Young trees transplant easier than older ones. Books will tell you to plant a young, small tree wherever possible: it will establish more quickly and will overtake the bigger, older one. At my place the distinction is less subtle: older trees always die, young ones sometimes don't.
The field has been left to its own devices for a couple of years. I have quaint ideas that it might be some kind of sanctuary for wildlife, or at least become one. So I have to mow a line in the grass in order to get at the soil. Then I hack a small area clear of grass using the pick-axe, and dig a suitable hole for planting the tree. Young trees are a good idea here too, because they need a smaller hole that is much easier to dig.
Once planted, I water the trees by taking over a couple of containers of water. At about 25 litres per container, that's a watering can-full for each of today's four trees. If it doesn't rain for a while, I'll water again as necessary until the winter wetness sets in. I did four trees yesterday and I'll do another four trees tomorrow.
The grass next to the fence at the northern edge of the field is short: next door's cows reach under the wire to eat it.