i dont know why this hasn't worked for me but this has been my goal to get to using the leaf blocks because they also give .1 of a bucket as wellThe key is not to depend on saplings for water..... I for instance use the water given by quests for the first two days, during this time I reserve my saplings and flesh for making dirt. As I'm running out of quest water I generally have enough stones for a slab furnace. Occasionally I have to sieve a unit or two of dirt, but not much. This allows me to quickly acquire shears and start using leaf blocks.