Posted: 05/03/2015 at 14:54
These Willows tend to be grafted, so the root stock will not suck up excess moisture like other Willows can. Willows only soak up water in spring to early autumn when growing, so no use in winter. I would improve drainage in other ways rather than trying to use plants.
I also think that smaller Willows will have more extensive roots within a few years than a 15ft one would.