Trees

Trees are background objects. You and every enemy walk straight through them, and hooks will not catch on a trunk; the Squirrel Hook is the one exception, and Climbing Claws do nothing either.

Where you swing matters. Hit the bottom center tile and the whole tree comes down. Hit anywhere else and you remove only that section, and nothing you cut off grows back, so a trimmed tree is permanently shorter. Axe power sets the swings per tile and also raises the average Wood per tile, so a better axe pays twice. The block directly beneath a standing tree cannot be mined or actuated.

Plant an Acorn and you get whatever matches the block under it, regardless of the biome you are standing in. Regular grass gives Forest trees, snow gives Boreal Wood, Jungle grass gives Rich Mahogany, corrupt and crimson grass give Ebonwood and Shadewood, hallowed grass gives Pearlwood, ash grass gives Ash Wood, and sand of any kind gives a palm. Every wood type can be farmed side by side on strips of imported soil.

Conversion works on trees already standing. Corrupt the grass under a Forest tree and it becomes an Ebonwood tree with its shape intact; purify the ground and it turns back. Pearlwood is the only type gated behind Hardmode, and ash trees are the only ones that grow at any depth.

• It needs one tile of suitable ground either side of its base for the stump, plus two clear tiles beyond that for branches. Call it a five tile column, sapling in the middle.
• Leave three tiles between saplings. At two, one grows and the other sits there forever, because the first tree's stump or lowest branch took the space it needed.
• Palms break both rules. No stump, no branches, so one tile between them is enough, but they want around 30 tiles of headroom.
• Vertical clearance is 9 to 20 tiles for most types and 14 to 25 for mahogany. Below that they grow very slowly or not at all.
• Anything needing a pickaxe to remove blocks growth within two tiles: torches, platforms, Sunflowers. Weeds and small flowers are fine.
• Saplings must sit at surface level or above. Ash grass and gem trees are the two exceptions and grow at any depth.
• Indoors is fine as long as there is no wall directly behind the sapling, or the wall is a fence.

Fertilizer matures a sapling immediately, but only when every growth condition is already met. Use it on a blocked sapling and it is simply gone. Infused Fertilizer demands far more headroom than the tree needs: roughly 24 to 35 tiles for ordinary trees, 29 to 40 for mahogany, 35 to 39 for palms and 26 to 31 for gem trees. Build a farm with a ceiling at the minimum height and the infused version refuses to work where the plain one is perfectly happy.

Hitting a tree without felling it shakes it, and a shake can drop an item or spawn something at you. The conditions are strict: a full leafy top rather than a broken stub, nothing within two tiles of that top, one shake per tree per day, and 500 shakes across the world in a day. Both counters reset at dawn, and axe power does nothing here.

What falls out depends on the wood. Forest trees give acorns, fruit, the Acorn Slingshot, and the Living Wood Wand and Leaf Wand that building projects want. Mahogany gives the Living Mahogany Wand and its leaf counterpart, plus bees. Ash trees are the easy route to Underworld critters like the Lavafly and Magma Snail. Fruit is the quiet reason to bother at all, since cooking has no other source for most of it. Cacti, bamboo and gem trees cannot be shaken.

Lay a strip of the soil you want, plant at three tile intervals and give the row about 20 tiles of clear air. Run a platform walkway above for access, but leave a gap directly over each tree, since a block within two tiles of a treetop kills shaking there. Palm farms pack tighter and give the most wood per tile of floor, at the price of 30 tiles of height.

Acorns come back off the trees, roughly one per leaf patch, so a farm feeds itself after the first planting. The Staff of Regrowth and Axe of Regrowth place grass directly, which beats carrying seeds. Keep lava out: it destroys most trees instantly, vanity, ash and gem trees aside.

Cacti, bamboo and Giant Glowing Mushrooms run on the same code, drop no wood and cannot be planted from acorns. Put an acorn on desert sand and you get a palm; cacti only appear on their own. Bamboo grows from submerged Jungle grass and needs a pickaxe rather than an axe, which catches everybody once. Gem trees grow on stone and still want an axe despite being made of rock.

The vanity trees, yellow willow and sakura, come as saplings from the Zoologist and drop whatever wood matches the grass under them. Plant one on corrupt or crimson grass and it eventually falls over by itself, so harvest those before they go.