Generally it will take from hours to a couple days. I have had some take 7 days but that is the longest my patience will last. I was under the impression the sooner they popped, the better the genetics - but I was wrong. My biggest, best plant took all of 7 days! We LIKE using different genetics, well some of them are just slower to get started....but make up for it at the finish! Kepp 'em growing!