Roots of a weeping willow does not take long to form. My husband and I get limbs off of his parents. We have planted about 6 now. You really don't even have to put them in water to start. all you have to do is plant them. Now when you first plant them, they will look like they have died. Give it a week or two and look, especially close to the ground and you will see the new limbs starting. Do not plant near septic or water lines. They will grow into the pipes. Always remember the roots will grow toward water. ... View related article.