Plant Coconuts Near the Ocean
If your coconut tree keeps dying it may be because of where you choose to plant it. Coconut trees will only grow near the ocean, and nowhere else. This means you are limited to five acres of available space, as the land next to rivers and lakes does not count. The tree must be planted at least one square away from the sandy part of the beach, but not actually in the sand. Your character is the same size as a square, so use him as a measuring tool.
Clear the Obstructions
If your coconut tree is too crowded it willl not grow. Make sure that there are no other objects next to the tree, such as another tree, a sign post, cliff wall, rock, bridge or building. Let the tree have one square's worth of free space in every direction. When you shake a fruit tree these squares are where the fruit will land. A coconut tree will not grow when something is next to it, because harvesting the fruit would be impossible.
Chop Down Existing Trees
There are hidden spots in "Animal Crossing: Wild World" where the game will not allow trees to grow because animals require them for walkways. Since you cannot see these spots, you can avoid them by planting coconut trees where another tree is already growing. Use your axe to chop down the existing tree and your shovel to dig up the stump before planting the coconut. Trees grown where another tree existed are guaranteed not to lie on these hidden walkways.
Testing Growing Areas
Not many trees grow one square away from the beach so it can be difficult to find guaranteed growing areas for your coconut trees. To rectify this situation, buy saplings from Nook's Store or collect some native fruit and plant trees along the beach to test which areas will grow trees. Wait four days to see which trees grow and then cut them down and replace them with coconuts. This way you never waste a coconut trying to find out which squares will grow a tree.