Wikia

Trees are the only source of Wood in the game with the exception of underground houses, and they can be found in all biomes apart from the desert or ocean. Cutting down a tree using an Axe will always give you some Wood and sometimes Acorns. All trees essentially have the same width, but their height can vary quite a bit. You can place torches on a tree.

It is not possible to cut down a tree by destroying the blocks under it, unlike a cactus on sand. The blocks will remain unbreakable until the tree grown on it is cut down.

It is advisable to cut trees at their lowest piece, the trunk. If you do not cut at the trunk, only the Wood above and where you are cutting will drop. Also, cutting the sides of the trunk, the roots, will not cut down the whole tree, but rather only that part. Trees will not grow back if they have been cut down and do not grow larger over time.

When cutting down a tree, the amount of Wood you get is based on how high the tree is, and how many branches and roots the tree has. For every leaf bush on a tree, there is a chance to get 1 Acorn, and the chance is highest with the leaf bush at the top.

When The Corruption reaches a tree, the tree's leaves will change to a purple color and it will become a Corrupt Tree. Corrupt trees drop normal Wood, but not Acorns. (Acorns can't be planted in corrupted areas, though the Corruption may spread underneath the tree, causing it to change color.)

When The Hallow reaches a tree, the tree's foliage becomes randomly colored blue, green, magenta, crimson, and yellow, and the upper area of the tree sports three tiers of bush, rather than the one upper bush found in the trees in the Forest and Corruption biome.

You may only place acorns on grassy areas: any already existing flora (grass, plants) will be cut down when you plant the acorn.

Trees planted by the player can grow to a maximum of 14 tiles high. Saplings have the following requirements to become trees:

The sapling's lower tile must have no wall.
There must be a tile of grass to the immediate left and immediate right of the grass the sapling is planted on.
There can be no trees less than three tiles away.
The sapling must not currently be in view on the screen.

You can't grow a tree at the edge of a step or cliff, next to a step or cliff, or at the edge of a patch of grass, even though you can plant acorns there. While trees can, very rarely, grow a distance of three tiles apart (two empty columns between them), they grow much faster at a distance of four tiles apart (with three empty spaces between them). For these reasons, it is recommended to plant acorns every four tiles on a long flat row of surface grass. Tiles more than 14 units above the planted grass do not have any effect on tree growth, so an optimal tree farm can have multiple 15-tile high levels. Unlike many plants, saplings will not grow into trees while they are on the screen; they will only grow when not currently in view.

If you run out of trees and acorns, you can purchase more from the Dryad.

It has been said by the creator himself that if there's one thing in the game you won't run out of, that's wood from trees.^{(Citation Needed)}

You can make overground jungles which automatically spawn trees. The trees will look dark green and have vines all over them. They will drop wood, so making a jungle for trees is recommended. Jungle Trees and jungle vegetation cannot be hallowed, but may be corrupted over a long period of time.

In patches 1.1.1 and beyond, Trees will spawn on snow in snow biomes. The leaf bushes on the tree will have snow on top of them. You can plant acorns on the snow and they will grow. Trees in the snow biome will not drop acorns. They can however be corrupted or hallowed.