How to Determine the Sex of a Cannabis Plant Learn How to Determine the Sex of a Young Cannabis Plant at 4 – 6 Weeks Old. Learn How to Determine the Sex of a Young Cannabis Plant at 4 – 6 Weeks Old. humboldtseeds2023-04-07T13:36:32-07:00 Share This Story, Choose Your Platform! FacebookTwitterRedditLinkedInWhatsAppTumblrPinterestVkXingEmail