Plant Propagation Techniques

Photo by Orla Swift

By Kaitlin Henderson

Whether you want to add new plants to your garden or expand old ones, knowledge about plant propagation is key.

Propagation is the process of making more plants. It includes a wide variety of techniques and levels of difficulty. The good news is you can choose which ones are right for your skills, time and gardening hopes. Even better news: you can learn these techniques in a series of Propagation classes in April and May at Duke Gardens.

Plant propagation is a great area for new and experienced gardeners to expand their abilities. Sara Smith, who volunteers on Duke Gardens’ propagation team, says she’s been on the team for five years and is still learning new techniques.

Smith and Jason Holmes, each of whom will instruct one of the classes in the series, shared the following tips and techniques.

Seeds are probably the best-known method of plant propagation.  Some seeds are stubborn, and in order to get them to germinate you need to apply specific techniques. Even in the vegetable garden, Smith points out, some seeds “will germinate a whole lot better if you do certain things, for example soaking beans overnight."

Perennials, like shrubs, can also be propagated by dividing. Beyond simply knowing what plants can be divided, you need to know the best season to divide a plant and how frequently to do it. Holmes noted that there's not always agreement on those aspects. "A lot of people tell you to divide your iris every five years, or every three years."

Cuttings are often the most fascinating part of propagation, Holmes says, and with good reason. With cuttings, you remove a plant part so you can grow it into a new, independent plant. This technique works well with woody shrubs and soft wood: for example, roses, lavender, rosemary and catmint.

Layering is a process I knew nothing about before talking with Smith. “It’s almost like cutting,” she said, “only you leave the branch attached to the parent." Layering is a useful propagation technique because it succeeds almost every time. But the technique varies from plant to plant. With blackberries, for example, "what you do is tip layering, which means that you just bury the stem tip into the ground."

Each class in the Plant Propagation series will focus on a different technique. Holmes emphasized that this is a great series for "anyone with a green thumb, with a love and a passion for plants." “All the techniques we're going to teach can be taken home and done" on your own scale, Smith added.

The classes are as follows:

•    Dividing a Plant: Tuesday, April 21, 10:30 a.m. - noon

Jan Watson, a horticulturist in the Terraces & Historic Gardens, will teach this class, showing participants what plants may be divided and how to do it, including when and how to successfully divide your plant.

•    Cuttings: 2 Tuesdays, May 5 &12, 10:30 a.m. - noon

Holmes will teach this two-part class on cuttings, taking participants through the selection of plants this technique can be applied to, the different methods of using cuttings and the materials to support them, and how to transplant the cuttings once they've developed roots.

•    Plant Layering: Tuesday, May 19, 10:30 a.m.– noon

Layering will be taught by Smith, who will provide knowledge about how the process works and how to use it successfully, especially the different hormones and techniques for different kinds of plants. Participants will get the chance to practice their new layering skills on plants from the Gardens.

All classes will be a mix of informational discussions and hands-on experience with Gardens plants to hone your new skills with guidance.

Each class will take place in the Greenhouse Classroom and has a participant limit of 15. You can sign up for just the techniques you'd like to add to your skill set, or all three. Classes are different every year and our instructors are incredibly knowledgeable, so you'll have the chance to learn something new even if you've been practicing a certain propagation method for years.

For more information about this series or to register, call 919-668-1707 or email gardenseducation@duke.edu. You can also check our website for additional information on these classes and our other adult education programs.

Check out a video about the Duke Gardens volunteer propagation team at our youtube channel.