diff --git a/mods/bg_tree/grow_leaves.lua b/mods/bg_tree/grow_leaves.lua
index 14d1d96..51750b4 100644
--- a/mods/bg_tree/grow_leaves.lua
+++ b/mods/bg_tree/grow_leaves.lua
@@ -10,6 +10,7 @@ local leaves_alive = modname .. ":leaves_alive"
 
 local max_grow_distance = 2
 
+-- TODO: turn this into an increasing ABM.
 blockgame.register_abm({
 	label = "grow leaves",
 	nodenames = {leaves_alive},
@@ -24,7 +25,7 @@ blockgame.register_abm({
 
 		local neighbors = blockgame.get_neighbors(pos)
 		for _, target in pairs(neighbors) do
-			if blockgame.chance(6) then
+			if blockgame.chance(2) then
 				blockgame.attempt_place(target, {name = leaves_alive})
 				minetest.get_meta(target):set_int("leaf_distance", distance + 1)
 			end