I have never found the various ones you can get in railway model shops that satisfying (often not very realistic at these smaller scales) and I have made my own in the past and they are fine but there is only so much time in the day! When I found an ebay shop in the UK (attercliffejunction) that sold 10mm hedges I gave up on the idea of doing my own. He does not have 10mm listed all that often but I have checked and he still does them - and if you are in the UK he goes to wargame shows under the name TreeFellas. The Bocage he did at my request (his brother does a 15mm set) so you may need to ask before he will prepare any for sale.
There are 3 different types and I will go through each and discuss the suitability for both 10mm and 6mm. The vehicle in the photos is a 1/144 CanDo Jagdpanther and the infantry and Adler 6mm Austrians. I have photographed with the hedges alongside a slightly raised road as well a on the flat.
I guess these are suitable for any area where someone would be keeping the hedges trimmed reasonably often, so I would be using around villages and along roads mainly.
For 10/ 12mm WW2 these work fine as low hedges. They look fine with a large vehicle like the Jagdpanther - which can fire over - and are about chest high on 10mm infantry (those pictured are Arrowhead Miniatures Americans):
For 6mm Napoleonics they also work well as a high hedge, but the guys can still just see over the top:
Rural, standard hedges:
A normal size hedge with more of a country feel. The hedges above are clearly a planted single variety hedge where these are a mix of different bushes etc. such as you would find in the country where things are left to themselves more.
For 10 / 12mm WW2 these work very well. There is some variety in the height of the hedge but big vehicles can still be seen behind them and can still fire over much of it
For 6mm Napoleonics these also work well and give a nice effect, plus the guys can still see over parts of the hedge:
I have only shown for WW2 as it would be more like low trees for 6mm! They give a good feel I think with large vehicles hidden behind and unable to shoot over: