added growth_check(pos, nodename) function

api.txt

@@ -39,3 +39,16 @@ The farming API allows you to easily register plants and hoes.
 	}
 
 Note: Any crops registered with the above function will use the new growing routines, also if crops are manually added with the {growing=1} group they will also grow.
+
+
+### Crop functions
+
+If a mod registers nodes to be used as crops using the {growing=1} group then an additional function can be used for custom growth checks instead of the standard 'are we above wet soil'.
+
+growth_check = function(pos, node_name)
+	-- check surrounding for jungle tree
+	if minetest.find_node_near(pos, 1, {"default:jungletree"}) then
+		return false -- place next growth stage
+	end
+	return true -- condition not met, skip next growth stage until next check
+end,