Gardening glossary
Rhizome
A rhizome is a modified stem that grows horizontally underground (or just along the soil surface), storing carbohydrates and producing new roots downward and new shoots upward at intervals along its length. From the outside, a rhizome can look like a thick root, but it's anatomically a stem — you can spot the nodes, scale-like leaves, and growing points if you look closely.
Common plants that grow from rhizomes:
- **Ginger and turmeric** — the "ginger root" in your kitchen is actually a rhizome - **ZZ plant** — the potato-like underground structure is the rhizome and primary water storage - **Snake plant** — spreads via thick white rhizomes that push new shoots up around the parent - **Bearded iris** — rhizomes sit at the soil surface and must not be buried - **Bamboo, mint, lily of the valley** — running rhizomes are why these spread aggressively - **Cannas, calatheas, prayer plants** — most marantas grow from rhizomes
Rhizomes serve three functions for the plant: storage of water and starch (which is why ZZ plants and ginger tolerate long droughts), vegetative spread (a single rhizome can colonize a wide area without ever flowering or setting seed), and dormancy reserves (the rhizome persists through winter while above-ground growth dies back).
For gardeners, rhizomes are a propagation gift. Division is straightforward: lift the plant in spring, find natural separation points where the rhizome narrows between growing clusters, and cut with a clean knife so each section has at least one growing eye and some roots. Let cut surfaces callus for a day before replanting to reduce rot risk.
Rhizomes also explain why mint and bamboo turn invasive: their rhizomes travel feet per year, popping up through lawns and into neighboring beds. If you want either, plant them in a sunken pot or use a rhizome barrier 12+ inches deep. Once a running rhizome is established in open ground, removing it requires digging out every fragment — any piece left behind regrows.