Propagation is any process used to multiply the number of plants in a group. There are basically two methods for doing this. Sexual propagation involves increasing plant numbers by germinating seed & growing the seedlings to maturity. This is probably the most widely used method by the majority of growers, including many agricultural grain crops. There are many different ways to pre-treat seed for attempting germination in the artificial setting of a greenhouse. These are processes used in an effort to overcome seed dormancy & attain successful germination on a man made schedule. Mother Nature does a wonderful job of overcoming dormancy so seed will germinate at the safest time for the seedlings to emerge into a growth friendly environment. We try to imitate those processes to successfully grow plants indoors.
Asexual propagation encompasses a variety of processes including leaf, stem, & root cuttings. Those slips that your Mom put into a jar of water in the kitchen window & watched until roots formed so she could plant them into the garden are simply stem cuttings. We would probably not agree that the water bath is really the best medium because of the high risk of mold developing but it sure seemed to work well for Mom! Dividing clumps of plants, such as Hostas, when they get very large is another form of asexual propagation. Planting bits of a rhizome root will give rise to new plant growth & is another form of cutting. The practice of grafting which is often used with roses & fruit trees is a type of asexual propagation. Another example is the layering used with raspberry canes where they are bent over to the ground & covered with soil where new roots will develop. All of these asexual methods develop plants that are essentially clones of the original specimens.
Julie Jenkins – Greenhouse Manager Ion Exchange
August 23, 2010