Making natural chicken barriers...

My current project is creating natural barriers to contain my free ranging chickens. Our property is just under 3 acres and we are lucky to have a low (knock on wood) predator load, so I am fortunate that I can with little worry, EXCEPT that, despite our rural location, one side of our property is bordered by a little neighborhood. Two of the other property edges already have natural deterrants (roads, mostly- my chickens don't go near the roads, although on one side before the road is about 50 feet of "wild" ground with high grass and brambles, and they don't go into that area either, which is a nice buffer) and the third side is forest, which I don't mind if they go into (and the neighbor who owns it doesn't complain), but I am petrified that they'll get into the neighbor's yard and cause trouble. One of the neighbors' gardens is about 20 feet from the property line, and I would feel awful if they got into it and dug stuff up!

Anyway, I'm planting an L shaped hedge in one open area between my garden fence and the very large Spruce windbreak, which is one of the areas they go through most often (and will most directly shield the neighbor's garden). I'm planting something dense interspersed with something fruiting (well thought out, huh?). And along the Spruce trees there are wild blackberry brambles which form a pretty nice natural barrier, but there are two spots, about 15-20 feet long, where the blackberry isn't thick enough to deter the chickens. It's not a direct shot to the neighbor's garden (it leads to a group of apple trees behind a fenced yard, which they' can't hurt), but from there there is a big opening in another windbreak that does get them there.

Long story short, what can I do to encourage the wild blackberry to grow thicker, OR what can I interplant with it that would do well and be dense enough to deter the chickens? It's a part to low sun area, shaded on one side by the spruce and the other by a grove of oaks, a large row of lilac bushes, and a large shed. I live in Minnesota (zone 4) so whatever I plant needs to be hardy to -20.

Thanks in advance!

blackberries will grow where their canes touch the soil, so, if you peg a cane down along where you want it to grow, it will root at t he nodes..also they will tip root, so if you peg down the tip along the row you want it go to it will root, generally they root best when pegged down in winter here..but not sure in your location.

We had a entire trellised black raspberry patch fall over in a snowstorm, and by spring all the places they touched the ground they rooted, blackberries will do the same thing.

another thing that would work in summer time, is jerusalem artichokes, also i have heard that chickens will eat them so extras could be dug for fodder.

you could try willow cuttinggs, or even berry bushes that will help to supplement your chicken food..like barberries, roses, blueberries, brambles, buffalo berry, hawthorn, elderberry, etc.

Wattle?? It is a natural materal fence now and a trellis for the berries.

http://www.paratusfamiliablog.com/2012/04/spring-antlers-wattle-fencing.html

Have you clipped their wings?

Wattle fencing may be a good temporary option (and possibly more permanent if I like it!) for this summer. I have a TON (almost literally) of grapevine we just pulled up that I could weave between some saplings. I've even been saving straighter pieces of various prunings and trees we've cut down. Thanks for that suggestion! It doesn't take much to contain chickens when they have plenty of space and interesting things to eat (and they're not being chased... of course they'll jump it if they're being chased!). I have 36 inch garden fencing blocking part of where I plan to plant the L shaped hedge right now and they haven't tried to get over it once even though none of them have their wings clipped. And soon their free ranging will only be part time- I plan to build more pens and do a rotational pasture thing because even though we have a low predator load I worry about DOGS. I'll also pin down a bunch of the blackberry branches because I've always wanted to encourage them a little- we love the "free" blackberries but the crop is usually pretty scant. Is it a bad idea to encourage them to grow in other places in my yard? I have a big yard and won't plant them anywhere near my annual garden, and I figure if their spreading so far has been contained then continuing to do so won't be a big deal...