How to Rock Root a Shrub to Create More Plants

You can rock root roses, holly, magnolia, large and small leaf rhododendron and many other plants. Rock rooting is more accurately known as layering which is simply covering a young stem by soil until it develops enough roots to survive on its own. The rock placed over the soil helps keep the branch buried. That’s the basics of how to rock root a plant to propagate new shoots.

rock root

How to rock root, or layer, to propagate a new shrub. Layering a shrub by weighing down a branch with a stone to keep it touching the soil.

How to Rock Root a Plant

• Find a low-slung branch on a plant you want to propagate.
• Strip the leaves from the portion of the stem that will be placed underground.
• Injure the bottom part of that section just slightly with a pocketknife in two or three places, taking care not to cut through it. I’ve never gotten an adequate explanation for why injuring a stem speeds up rooting, and it’s not necessary if you want to skip it.
• Put the wounded (or unwounded) stem in a trench about its same length and about two or three inches deep.
• Cover the stem with rich soil containing a little vermiculite, leaving a slight depression above the trench to better allow water to collect.
• Put a heavy rock or brick over the springiest part of the stem to keep it in place, and use another rock where the stem exits the trench to direct the plant into a vertical growth pattern.

Under ideal conditions, a branch layered in the ground will be well rooted by the end of September. Test it by removing the rocks and tugging on what will be the new plant. If there’s resistance it’s like got a well-formed root mass. You can clip the non-rooting portion closest to the mother plant. Remove the clone—that’s technically what it is—and replant where you want it.

Gregg Coppa is a frequent contributor to Horticulture. Here are his tips for keeping critters from eating your garden.

Tips for propagating annuals.

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