diff --git a/plants_lib/init.lua b/plants_lib/init.lua
index eff24d5..db5f564 100644
--- a/plants_lib/init.lua
+++ b/plants_lib/init.lua
@@ -250,6 +250,7 @@ function plantslib:generate_block(minp, maxp, blockseed)
 				end
 			end
 		end
+		plantslib.surface_nodes.blockhash = nil -- nuke the block cache after using it (prevent a mem leak).
 	end
 end