You might want to fill in on a case-by-case basis. If some crowns have growth 5 inches or more, add about 2 or so inches more soil over the base. For those that are under that amount, you might wait until the spears appear and reach a larger size — also, you don’t want to cover any foliage that develops. Once growth reaches the minimum size, you can start filling in about 2 inches every two weeks until trench is filled. To keep soil outside the trenches from washing away, you might try placing a tarp over it and around the edges. Hope this helps!
You might want to fill in on a case-by-case basis. If some crowns have growth 5 inches or more, add about 2 or so inches more soil over the base. For those that are under that amount, you might wait until the spears appear and reach a larger size — also, you don’t want to cover any foliage that develops. Once growth reaches the minimum size, you can start filling in about 2 inches every two weeks until trench is filled. To keep soil outside the trenches from washing away, you might try placing a tarp over it and around the edges. Hope this helps!