A number of tree species can be propagated with root cuttings. Examples include weeping willow, poplar and crabapple. In general, trees that send up suckers from their roots are the best candidates for propagation through root cuttings. Be careful with fruit trees, though, because many are grafted. With root cuttings you will be propagating the root stock variety, not the grafted variety.
Select the tree you want to propagate. Pick a nicely shaped, healthy specimen. In mild climates, you can take root cuttings any time between October and March, when trees are dormant. During dormancy, the tree’s growth energy is stored in the roots to await the spring. In places with frigid winters, take cuttings in the fall before the ground freezes or in spring when the ground thaws enough for digging. Dig carefully with the shovel to expose the roots on one side of the tree. Don’t expose more than one-third of the roots. Look for living, healthy roots about as thick as your little finger. Avoid roots that look black and dried out.
Cut the selected root. Cut a section 6 inches long with the pruning snips. Snip each cutting into two 3-inch sections. Keep track of which end of the cuttings pointed toward the plant. That is the “top” end from which a new plant will grow. To tell the ends apart, cut the top end flat and cut the opposite end at a slant to form a pointy end. Set the cuttings aside and shovel dirt back over the exposed tree roots. Water well to help the dirt pack back down on the roots.
Fill a large, 12-inch-deep planting pot with commercial potting soil, and add water until the soil is moist throughout, but not sopping wet. Dip the pointy end of your root cutting into the powdered sulfur, covering the bottom half of the cutting. This will control root-rot fungus. Push the pointy end into the potting soil until the flat top end of the cutting is one inch below the soil surface. Cover the cutting. Make sure root cuttings are oriented correctly. They won’t sprout if planted upside down.
Put the pot in a warm, sunny indoor location. Avoid cold drafts and freezing temperatures. Water when the soil becomes dry to the touch. New shoots should appear in about four weeks. Water the new shoots with a half-strength houseplant fertilizer solution. If you get multiple shoots, thin to the strongest shoot. Once the new seedling tree is growing well in your pot, wait until frost danger is past and then transplant it to an outdoor location.
Things You Will Need
- Pruning snips
- Potting soil
- Powdered sulfur
- Large plant pot, 12 inches deep
- Water-soluble houseplant fertilizer
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