From Package instructions
"How and When to Apply
BEEVITAL® HIVE CLEAN applied before the reproduction period (before Dec 24th and beginning of January), will result in significant increase if the growth of your bees.
Feb/Mar/Apr - when bees start collecting pollen, up to 20 ml
May/June - during intensive growth of the bee colony, up to 20ml
July/Aug - during honey harvesting, up to 15ml
BEEVITAL HIVE CLEAN applied before Sept 1st helps the bees to survive winter and makes them stronger.
Nov/Dec/Jan - depending on the conditions and temperatures (lowest temperature in which it may be applied is -5 C but most effective in temperatures of +5 C and more) should be applied on a hibernated group of bees, up to 15ml.
An important factor of the effectiveness of BEEVITAL HIVE CLEAN is to apply it at least once when the Queen has stopped laying (Autumn to Spring).
Many beekeepers use HiveClean like a prophylactic, administering small doses whenever they open a hive. It must be remembered that you cannot overdose when using HiveClean."