SBK is a brushwood killer, and is therefore intended for use on woody parts of shrubs and trees, having first drilled into or cut into the wood. It can also be used on persistent tough weeds, but it doesn't kill through the green - it kills anything it touches, remains in the soil if it gets on it, and isn't that useful as a spray. You'd be best off buying some glyphosate or Weedol 2 and spraying with that instead, shielding any surrounding green growth that you want to keep when you do spray.

Yes most likely it would damage not only the surrounding plants, but poison the soil so nothing would grow there until it breaks down. There's also wind drift.

Personally, I would cut everything to ground level. Then rent a commercial grade roto-tiller (gasoline powered) or tractor and plow the whole thing under. Plant new grass, etc. It's a big messy job but think of the end result - use of your garden.

I have to agree with Snoopdog. If you have the time and the inclination, then I would cut the brambles off all at ground level and meticulously fork over the ground several times whilst lifting the nettles and bramble roots as you go. I'm sorry to say, under no circumstances would I rotovate the ground as you will chop the bramble roots in many pieces and each piece left will root.

Agree with not rotovating or tilling - hand digging is best, to extract the roots, if they don't die with weedkilling treatment.

I've only just noticed your mention of brambles - these certainly won't be killed by either glyphosate or a spray of SBK. If they're large, you need to cut them down, expose the roots and apply SBK to cuts in the woody parts of the roots. If they're small, you may be able to dig them out.

Bathgate: I know you're in the States, and because I belong to a States based gardening web site, I'm aware that you guys usually have much larger gardens (or yards, as you call 'em) than we do here, and use of machinery to till and rotovate is normal. Mostly, in the UK, we have what you'd consider a postage stamp for gardens, even though we might think they're quite large - hence the difference in the level of use of machinery. By the way, the term 'yard' when used referring to gardens in UK usually means a small concrete or paved area, often at the back of small cottages. It's another world!

Brambles have roots that go down at least 3 feet and so will you as you try to dig all the roots up. Your first attempt at digging will be like a tangled mess of titanium barbed cable ready to claw you to death. The roots form a thick spreading mat underground. I would certainly opt for the use of heavy equipment/machinery designed for the task. Power tools!

Either way, you'll have to deal with the clean up - rake up the bits left behind.

You won't get it all with the first attempt. New plants will crop up here and there, but they are much easier to deal with as seedlings then years old mature plants.

Bamboo - I have visited many beautiful gardens in the UK - at Stratford-upon-Avon, Rochester - Leeds & Liverpool. A wonderful tour.

Are you wanting to use the ground for planting or grass?

If grass then you can glyphosate the nettles and cut the brambles back to the ground. As soon as they regrow start mowing. We did this and in a few months the brambles gave up and disappeared. Much easier than digging them out because they run underground and if you miss a bit the just grow again. This wouldn't work on uneven ground though unless you had a hovermower..

Has anyone ever seen a time lapse film of how brambles spread? They actively 'layer' from their tips, searching and waving around looking for a likely place to root, not unlike triffids lol!!! Get the worst out, then progressively stop them photosynthesizing!! Mow or strim repeatedly, they WILL give up during the course of the year. I have bindweed AND horsetail. Try that for persistence.... heavy carpet covered with bark is only way for me, and glyphosate on where the little b****s poke through the edges. I manage to keep a nice shrub border going despite it, but had to give up on roses in that area.