As a healthy marijuana plant thrives, it should hit several stages of growth on its way from seed to weed. Knowing what these milestones are before you start will give you an idea of what to expect as you cultivate your crop. Ultimately, marijuana plants are living objectsâ€”they are as susceptible to chance and change as the rest of us. There are no foolproof guidelines that can guarantee you the best product ever. Even if you follow every suggestion in this grow guide to the letter, some plants simply might not thrive.