I feel your pain. I live in zone 5b also, and unfortunately have not yet overcome. But I'll share what I have found. 1. One person cut the bindweed at ground level, covered with paper or cardboard, put mulch over that, and left over winter before planting his garden. It worked for him. He has to spend about 5 min. a week weeding where it has come through. This is in England, so I don't know how that translates to our soil and climate. 2. Bindweed grows best where the soil is poor. (Not that it won't grow anywhere else). But anyway, someone claimed that they just kept after it, as well as enriching and lightening the soil year after year, growing their garden plants anyway. After not too many years of this, they claimed the bindweed just kind of gave up. (I would like verification). 3. I am trying my variation on both. I am cutting the weed at ground level, (making sure the tops are thrown out). I am putting cardboard over it, and covering that with dry leaves (I have access to a lot), and planting in spaces between as much as possible. I already have to watch it, as it likes to to coil up in white stems, or even grow out to the edge into the sunshine. I am enriching where I plant what I want to grow. I haven't been able to find better advise anywhere, and believe me, I have looked. I am unwilling to use poison on it, as that would poison whatever I grew next. Let me know if you find anything!
I feel your pain. I live in zone 5b also, and unfortunately have not yet overcome. But I'll share what I have found. 1. One person cut the bindweed at ground level, covered with paper or cardboard, put mulch over that, and left over winter before planting his garden. It worked for him. He has to spend about 5 min. a week weeding where it has come through. This is in England, so I don't know how that translates to our soil and climate. 2. Bindweed grows best where the soil is poor. (Not that it won't grow anywhere else). But anyway, someone claimed that they just kept after it, as well as enriching and lightening the soil year after year, growing their garden plants anyway. After not too many years of this, they claimed the bindweed just kind of gave up. (I would like verification). 3. I am trying my variation on both. I am cutting the weed at ground level, (making sure the tops are thrown out). I am putting cardboard over it, and covering that with dry leaves (I have access to a lot), and planting in spaces between as much as possible. I already have to watch it, as it likes to to coil up in white stems, or even grow out to the edge into the sunshine. I am enriching where I plant what I want to grow. I haven't been able to find better advise anywhere, and believe me, I have looked. I am unwilling to use poison on it, as that would poison whatever I grew next. Let me know if you find anything!