Nitrogen fixing plants are a great way to build up nitrogen in the soil without using chemicals. But you can’t expect to just plant them and leave them.
The plant wants to use the nitrogen for its own purposes, namely leaf and seed production. So if you want to get the nitrogen benefit for your soil and other plants you will need to trim them back before seed is set.
Most annuals can be taken down to two or three inches, with some leaves showing. Perennials can usually be cut down to the ground. Many shrubs can be coppiced every few years, while the remaining shrubs and trees can be selectively pruned or even hedged.
Even some trees can be coppiced, but you must choose the tree wisely. And you must commit to caring for the tree as it recovers. Coppicing can cause trees to grow back with structural weaknesses that may create safety problems later on.
Whatever you plant and however you decide to maintain it, you should spend the time to research it before hand. Then, pay careful attention to how it grows for you and record what happens in a journal so you can refer back to it latter.
Good luck and let me know what happens!
