my cinderella 99 plants are about 3ft tall and 6-7wks old. i tried to take clones the other day but there wasnt much to select from. the branches towards the bottom of the plant were actually pretty long. i understand clones should be 2-3 inches? did i wait too long to try to take clones? are some strains more difficult to take clones from? does it stress the plant to take clones from it? i took about 20 cuttings and only 2 look like they have a future. what am i missing here? thx in advance for any advice.