Corruption and Hallow (and the other spreading biomes) only spread through blocks, and compatible blocks (Dirt at Normal (and at contact), Stone, Sand, Ice and Grass at Hardmode) at most. Think that, if these biomes spread through walls, you would have to demolish them.
What can hallow not spread through?
mud areas
The Hallow, unlike Crimson and Corruption, cannot spread through mud areas such as found in Jungles or Glowing Mushroom biomes. The Dryad can tell the player the percentage of Hallow and Corruption/Crimson in the world.
How do you stop the Hallow biome from spreading?
Upon the activation of Hardmode, Hallow and Corruption/Crimson start spreading, potentially converting the entire world….Notes
- Thorns can grow from Crimson, Corrupt, or Jungle grass.
- The Dungeon can completely prevent the spread of Hallow and Corruption/Crimson if it reaches down to the Underworld.
Can Hallow spread through blocks?
Corruption, Crimson and Hallow will spread to stone, sand, ice and dirt that are up to three tiles away. Almost all other blocks are immune to Corruption and Hallow, including Wood, Clay Blocks, Ash Blocks, Silt Blocks, Obsidian, Ores, Gems, and all bricks (except Pearlstone, which will spread Hallow).
How does Hallow spread from grass to stone?
Corruption/Crimson/Hallow spreads through plain Stone blocks, grass, sand, and ice. They will also convert jungle grass to regular grass, and mud to dirt in order to spread to the grass.
How does Hallow spread in terraria hardmode?
Corruption/Crimson/Hallow spreads through plain Stone blocks, grass, sand, and ice. They will also convert jungle grass to regular grass, and mud to dirt in order to spread to the grass. In hardmode, one affected block can spread to other blocks up…
Can you spread the Hallow above or below ground?
The Hallow can provide a challenge to players new to Hardmode, so sufficient preparation is recommended. The Hallow can be spread above and below ground with Pearlstone Blocks, Pearlsand Blocks, Holy Water , Hallowed Seeds, or with the Clentaminator. The rules for spreading The Hallow are as follows:
Can a sunflower stop the spread of the Hallow?
Sunflowers will not impede the spreading of The Hallow (neither pre- nor post-WoF). The Hallow can be planted in a world where the Wall of Flesh has not been killed but, similar to the Corruption/the Crimson, it won’t spread through Sand and Stone. It will spread the Hallow grass over default grass, however.
