I forgot to mention, if you coppice your willows annually which is traditionally the way they are managed for producing basket material, the stems likely will not be mature
enough to flower. I am not sure how many years it takes to flowering. Possibly leaving the stems to grow 2-3 years and harvesting them at larger sizes for basketry would allow flowering. In that case you would need to stagger the harvest years so some plants with mature branches would always be present.