One of my very favorite things to do is the planting and transplanting of trees. I am personally responsible for establishing the happy and healthy lives of hundreds of trees encompassing species from Aspen to Walnut.
The single most important consideration after successfully planting a tree is an adequate supply of water to assist the tree in becoming established in its new site. It can be difficult to deliver a sufficient amount of water to young trees in an effective fashion, especially if you have planted or transplanted more than a couple of them.
What tends to happen is the water is delivered as one complete dose at the base of the tree and often times two thirds of that water just runs off and is of no real benefit to the tree. Even if you make a water basin at the base of the tree, when you fill that basin the water tends to seep sideways quicker than soaking down into the root zone.
I "invented" an extremely simple way to deliver water to young trees in the most effective way possible. The only better idea than mine is the use of a direct root zone probe. I call my invention The Dribble Bucket. I use five gallon utility buckets, but any large plastic bucket will do. On the side of the bucket, towards the very bottom edge I make a hole about 3/16 inch diameter (a little less than the diameter of a pencil).
When I set the dribble bucket next to the tree and fill it with water, it delivers the whole five gallon payload in a manner which allows all of the water to soak slowly right down into the root zone. I know this method is extremely effective because I'll often give an individual tree two or three buckets of water in this manner and when I'm done, the surface soil around the tree will still remain nearly completely dry. This tells me that the water I have provided is soaking right straight down to the root zone where the tree can make the best use of it. The picture below shows just how happy a tree can be when it gets ample water.