When I plant trees they always die, I water them but they still die anyone..

Some trees have to be planted in specific areas. For e.g. The cocounut tree must be planted near the shore.
It takes four days for the tree to grow and must be watered at least once every day.

Whether you water the wilted trees or not, after the second day, they WILL disappear. If your trees have already survived one day, then they will survive all the rest, unless of course you cut them down.

Tree PLACEMENT is vital to the growth of your trees. Not every piece of land on animal crossing: city folk supports tree growth.
When I was perfecting my town, I planted the trees wherever I saw best fit. After one day, some had grown into the second of five stages, and others were wilted. Once wilted, it is a FACT that trees can not grow in that spot. (To designate this as a spot where trees can not grow, I buried a shell there until I was finished planting trees.) I called these spots "deadspots."

If you're trying to plant a tree you want to grow and not have to suffer waiting to see if it's a "deadspot", you can always cut down an existing tree and plant your new tree there. This will guarantee the tree to grow.

Don't skip ahead, even a couple hours!