As you have such a large area you could always leave 2 or 3 patches of ground where you can allow the brambles to grow to an area of say 3 or 4 sq metres. They will form a dense clump that is of great benefit to all sorts of wildlife and will save you the hassle of digging out every root you see. You can control the size and spread by strimming (very carefully!) or mowing around the perimeter. When I lived in Hampshire my local council used to do this in several of the parks, including the one with the famous white squirrels. Not only will it save you a lot of labour but you should also have a huge crop of blackberries to share in and there is nothing like homemade bramble jelly
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As you have such a large area you could always leave 2 or 3 patches of ground where you can allow the brambles to grow to an area of say 3 or 4 sq metres. They will form a dense clump that is of great benefit to all sorts of wildlife and will save you the hassle of digging out every root you see. You can control the size and spread by strimming (very carefully!) or mowing around the perimeter. When I lived in Hampshire my local council used to do this in several of the parks, including the one with the famous white squirrels. Not only will it save you a lot of labour but you should also have a huge crop of blackberries to share in and there is nothing like homemade bramble jelly