This illustration comes from The US Army History institue, Combat lesson Number 4. This is the best illustration I have seen that describes the hedgerows of Normany.

The way I build my hedgerows...
1 I start with a mound of Sculptimold
2 Shape it in a mound, reflecting the shape in the illustration above
3 I paint the mound with a ground color of house hold latex paint
4 Next, I start my ground cover by using presifted dirt from my backyard. I use woodland scenics, mixed with a little white glue.
5. I start layering the whole area with static grass, and taller "planted" grasses.You can do this by punching holes and plant it in clumps, but I also use a technique of covering the ground with a thicker soultion of WS and white glue precolored with the latex paint to give a more natural look.
6 Then I add my ferns, small weeds, flowers, the midsize plant life. When I am satisfied with the look them I start adding the taller stuff and use a variety of "bushes" some are thin and some heavier woody style like I mentioned in my early post of the sweetwater materals following the method mention earlier.
7 When I have completed the construction of the "bushes" I plant them by drilling holes in the mound. You have to go back and make some touch ups.
8 Now the taller trees which, I make all different sizes. Sweetwater has different sized sage brush "trees" they range in size 2" to a12" or even some taller. The taller trees I add wire or other natural growths (dried roots are good) to them for the finer branches. Dill holes into the tree base and glue in the "branches". If I use wire branches I use an acrylic base putty to texture the wire frames as well as the tree to create a variety of tree bark types. Add leafs, many products can be used here... Herbs, flock, PE (expensive) choose what you like best and fits your budget...
9 Drill holes for the trees and again glue them in securely by pinning them with heavy wire or even nails.
At some point when I am finished with my Carentan project I fully intend to do a feature of this technique... Hope this help you all for now...
Paul