you can snap off leaves with your hands, it is best to use a sharp knife to avoid any tearing or otherwise damaging the plant. use the knife to cut a leaf at its base where it meets the soil line.
simply squeeze the gel out of the inside of the leaf and it is ready to use. if you do not need all the gel inside, you can wrap the leaf in foil and place it in the refrigerator where it will keep fresh for four to five days. the leaf will callous over at the cut, but if you gently scrape the cut area, you will be able to 