Plant Propagation: Overwintering Perennials
Do you love the idea of getting plants for free? Would you like to know how to over-winter your favorite perennials to save for planting next spring? Would you like to learn a new gardening skill? If you answered “yes!” to any of these questions, let me introduce you to the plant propagation technique of taking cuttings.
Many types of plants are propagated by cuttings. A cutting is a piece of plant which is removed from the parent plant in order to form a new plant (these new plants are called clones). This magic occurs through the processes of differentiation and de-differentiation. The most important ingredient in this process is meristematic tissue which if found in the nodes (the small bumps on the stem).
Cuttings can be taken any time the plant is actively growing, but late-summer through fall is a good time for a beginner to start taking cuttings of favorite perennials. At this time of year, stems have reached the semi-ripe stage (the current season’s growth has begun to firm and will bend without snapping).
You can purchase propagators specifically made for taking cuttings, but you can also use any container as long as it is clean and has drainage holes. My favorite propagator is one that you can easily make at home and has yielded good results for me. Instructions for assembling this propagator, with photographs are on my blog at https://www.l3h2inc.com/post/my-favorite-propagating-tool-a-self-watering-propagator-in-10-easy-steps. Also included in this blog are directions for taking a cutting with photos.
The night before you plan to take cuttings, fill the container with sterile potting soil and water it well so that it will be damp when you are ready to “stick” the cuttings. Water the plants that you intend to take cuttings from so that the tissues are full of water (this is called being “turgid”).
Place the container filled with soil on a stable surface that is at a comfortable working height. Assemble the other needed materials: hormone rooting powder, a sharpened pencil, labels, a permanent marker and a container for collecting discarded leaves.
Then grab your pruners and head to the garden!
Depending on the plant and the distance between the nodes (this distance is called the internodes), a 2-6” long stem cutting is usually sufficient to assure that at least two nodes will be under the soil surface. The nodes are where the new roots will sprout from.
When removing the cutting from the plant, cut just above a node (where a leaf is actively growing or where you feel/see a “bump” on the stem). Take the cuttings from this plant and head to the propagating bench.
When you look at the stem you’ve removed, there will be a piece of stem below the bottom node on the stem. You want to remove this extra piece of stem so that it doesn’t rot under the soil.
Pinch out the growing tip and remove any flowers, then remove all but 3-4 leaves. If the leaves are large (like a Hydrangea leaf), cut them in half. There is a photo on the blog that shows what the cutting should look like. It will look very bare, but keep in mind that you want just enough leaves so that photosynthesis can occur. Prepare all the cuttings this way.
Remove a small amount of rooting hormone powder from the bottle and place it in a small dish. I know it’s tempting to stick the stem directly in the bottle, but if you discover later than this stem has a disease you will have to discard the entire bottle or risk infecting future cuttings.
Make a hole in the soil with the pencil. Then dip the end of the cutting in the rooting hormone and place the cutting in the soil. Use your fingers to gently press the soil close to the stem. Repeat until all the cuttings have been “stuck”. Cuttings should be far enough apart that leaves are just touching. Place a label identifying the cuttings in the propagator.
If you want to take more cuttings, clean your pruners (anti-bacterial wipes are a handy way to do this) and move on to the next plant.
When you have stuck all the cuttings for the day, fill the clay pot with water and place the propagator in a shady spot. Check daily to see if the water needs to be topped off in the clay pot.
Most plants will produce roots in four to eight weeks. You’ll know that roots are forming when you see new growth on the cutting. If flowers appear, remove them so that the energy needed to produce roots doesn’t transfer to flower production.
If you see new growth in six weeks, give the cutting a slight tug. If roots have formed, you will meet resistance. With a teaspoon remove individual plants and transplant them into a 4” pot. When the plant has almost filled the 4” pot with roots, it can be planted into the garden.
Some tips to help with your success:
Taking cuttings from healthy, established plants won’t hurt them; often times it is healthy for the plant, but you should select stems carefully to avoid disfiguring the plant. Never remove more than 30% of the plant material at any one time.
Collect material early in the day when the plant it fully turgid (full of water) and before the sun diminishes the plant’s vital water reserves that have built up overnight.
If you are unable to stick the cuttings immediately, store cuttings in separate, clean plastic bags (or buckets of water), label them and place the bags/buckets in the refrigerator, where the cuttings will remain in good condition for a number of days.
Perennials suitable for propagating in the fall: Acanthus (Bear’s Breeches), Achillea (Yarrow), Armeria (Thrift, Sea Pink), Artemisia (Wormwood), Bergenia (Elephant’s Ears), Dianthus (Carnation, Pinks), Diascia (Twinspur), Echinops (Globe Thistle), Eryngium (Sea Holly), Euphorbia (Spurge), Gaillardia (Blanket Flower), Gazania, Geranium (Cranesbill), Helichrysum, Osteospermum, Pelargonium, Penstemon, Pepperomia, Phlox, Tradescantia, Tricyrtis (Toad Lily), Verbascum (Mullein), Verbena (Vervain) and most succulents. But don’t be limited to this list, experiment with other perennials in your garden.
If you are taking cuttings of hardy perennials, the propagator can be left outdoors in a protected location (cover when a freeze is predicted). If you are taking cuttings of tender perennials (those that are perennial in warmer climates) to over-winter for spring planting, follow the same process, but bring the propagator indoors and keep it under lights or near a bright window.
I have found it helpful to keep a propagation journal that includes the date, the plant name, the number of cuttings taken, how long it took to produce roots, the number of cuttings that rooted (not all will root every time), when you transplanted the plant into a 4” pot and when you transplanted the plant to the garden. It’s also helpful to have a reference book that you can refer to for specific requirements for certain plants.
Once you master this simple skill of propagation, you’re going to find yourself with a pair of small clippers in your purse or pocket and you’ll be requesting cuttings of favorite plants that your friends and neighbors have in their gardens.
If you catch the propagation bug, consider starting a propagation study group with six like-minded friends. Every other month each person takes a subject on propagation to teach the group and then everyone heads out to the hosts’ garden to take cuttings. Everyone learns and everyone goes home with plants. And who doesn’t love free plants?!