Q.Brussels Sprouts
I harvested to batches of buttons and I keep my main stem trimmed of leaves. Now I think it is getting too tall and no more buttons are forming good. Should I cut it in half and plant the top part?
You can prune the top of the plant, but it will not reroot.
Here are some links with more information.
https://www.gardeningknowhow.com/edible/vegetables/brussels-sprouts/harvesting-brussel-sprouts.htm
https://www.gardeningknowhow.com/edible/vegetables/brussels-sprouts/pruning-brussels-sprouts.htm
https://www.gardeningknowhow.com/edible/vegetables/brussels-sprouts/brussels-sprouts-winter.htm