Root Cuttings

Pulling up a weed doesn’t always mean the end of that weed. One tiny piece of root left in the soil may be all that’s needed for a new weed to grow. That’s the downside of root cuttings. The good side is that you can use that behavior to propagate many desirable plants.

Elm root cuttings (Gmihail) CC-BY-SA-3.0-RS

Just as scions can produce new fruit and nut trees, the roots of many herbaceous perennials and a few woody plants can generate free plants. Plants that have been grown from root cuttings rarely need any special care, and they tend to grow well. These baby plants have the advantage of starting underground, free of many aboveground pests and pathogens, such as aphids and leaf nematodes.

Root cutting candidates

Plants suited to this method generally have fleshy roots or runners. Here’s a partial list of edible plants that you can propagate from root cuttings:

• Artichoke
• ​Basil
• Blackberry
• Blueberry
• Currants
• Curry plant
• Elderberry
• Fig
• Gooseberry
• Grapes​​

• Lavender
• Lemon balm
• Mint
• Mulberry
• Passionflower
• Raspberry
• Rosemary
• Sweet potato
• Tomato

Raspberries (Kate Russell)

How to take root cuttings

Take root cuttings when a plant is dormant when nearly all of its available nutrients and carbohydrates have been pulled into the root system. If a plant is large, you can dig soil away from the root system to select roots for cuttings. Otherwise, dig up the plant to be propagated and rinse off its root system. Select healthy roots that are the diameter of a pencil. Cut off those roots with freshly sharpened, sanitized pruners as close to the crown as possible. If you don’t have pruners, a knife is better than scissors to avoid crushing and damaging the root.

Take no more than one-third of a plant’s root system and replant the parent plant right away. As always, be sure to mud it in, rather than tamping down the soil. Once you have your roots in hand, follow these steps to get the best results:

• Prepare large pots with soilless potting soil or prepared cuttings compost*.
• Snip off the skinny root ends and trim back any fibrous lateral roots.
• Take the remaining roots and cut them into 2- to 4-inch segments with horizontal cuts at the upper end and angled cuts at the lower end, tossing any tiny leftover triangles. This will ensure that they are planted the right way up.
• Insert each root segment into the soil with the pointed end down and the flat end just under the soil line. [If you are working with especially fine roots, you can lay them horizontally and cover them with no more than half an inch of soil.]
• Water lightly.
• Place pots in a cold frame, greenhouse, or another protected area.

*Cuttings compost is different from what you get from your compost pile. Since these roots already contain plenty of nutrients, what they need is a medium that drains especially well and is easy to move through. If the soil contains too many nutrients, the roots are less motivated to reach out and grow. Cutting compost usually has a high ratio of grit, sand, or vermiculite.

Many people cover their cuttings with plastic to retain moisture, but that can backfire in the form of fungal disease. I don’t use plastic. For me, it’s safer to monitor the soil and water lightly, as needed. Green shoots should appear in springtime. If nothing happens, take a closer look. You can pour the soil onto a cloth or sheet of newspaper to see what's going on. Sometimes root cuttings fail, and sometimes plants are slower than we'd like. Give them more time.

Dragontree seedlings grown from root cuttings (Gmihail) CC-BY-SA-3.0-RS

What about rooting hormones?

Rooting hormones, or auxins, are frequently used when taking stem cuttings in summer. Auxins encourage root development in those stems, but they are not necessary when working with root cuttings. Roots already know what to do.

Some plants are easier than others to propagate from root cuttings. Artichokes are, by far, the easiest I have ever found. This massive artichoke plant provided several daughter plants, and all I did was take a shovel, place it next to the crown, step on the shovel and chop off whatever was underground at that spot. I’d dig it up, rinse it off, remove any thin or damaged bits, dig a hole, plant it, and mud it in. That’s all it took. I had baby artichoke plants wherever I wanted them, for free.