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What Is a Rhizome?
A rhizome (also known as a creeping rootstalk or rootstock) is a type of plant stem that grows horizontally underground or across the soil surface. Its main purpose is to store carbohydrates and proteins so the rhizomatous plant can survive between growing seasons. This stored food is kept in the rhizome's enlarged tip, the stem tuber.
Rhizomes also store food to produce energy for vegetative reproduction—a form of asexual plant reproduction that allows gardeners and farmers to propagate certain plants. Rhizomes expand horizontally, developing new root systems and sprouting new shoots from nodes (the area of the stem where buds form). Examples of rhizomatous plants that propagate through vegetative reproduction include lily of the valley, canna lily, ginger, and asparagus.
Rhizome vs. Stolon: What’s the Difference?
A rhizome is a plant stem that grows horizontally (generally underground) and produces both shoots and roots. Similarly, a stolon is a horizontal plant stem that grows above the ground and takes root to create new plants. Whereas a rhizome is itself the main stem of a plant, stolons are offshoots of a stem. Unlike stolons, which tend to have long internodes (the section of the stem between the nodes), rhizomes generally have short internodes.
3 Types of Rhizomes
Rhizomatous plants are classified based on whether they grow above or below the surface of the ground.
- Underground rhizomes: The most common type of rhizome is an underground stem. Types of plants with underground rhizomes include ginger, poison ivy, bamboo, Bermuda grass, rhubarb, and hops.
- Above-ground rhizomes: Less common are rhizomes that grow directly at or slightly above the soil surface. Some types of irises and ferns grow from above-ground rhizomes.
- Multi-tiered rhizomes: The rarest rhizome of all is one that forms multiple layers of growth. The large majority of rhizomes grow roots and shoots from a single layer, but some plant species—such as the giant horsetail—form several rhizome layers.
How to Plant Rhizomes in Your Vegetable Garden
Looking to grow your own rhizomes? Whether you plan to purchase rhizomes or obtain them from vegetative propagation, there are general guidelines to follow when planting. Be mindful that these are broad guidelines, and different plant types may have unique planting instructions.
- Pick a planting time based on the type of plant. Plant late-summer blooming rhizomes in the early spring, and plant spring-blooming rhizomes in the fall.
- Choose a sunny location. An area that receives at least six to eight hours of direct sunlight is ideal for most rhizomatous plants.
- Propagate rhizomes from the original plant. If you're propagating your rhizomes, dig up the original plant and cut the rhizome into separate sections. Each section should have at least two nodes to be suitable for replanting.
- Plant rhizomes in well-drained soil. Soil with good drainage is key in order to avoid oversaturation. Mix organic matter—like compost, leaf mulch, or peat moss—into the soil to create a better growing environment. A general rule of thumb is to plant rhizomes deeper in sandy soils and shallower in clay soils.
- After planting, water thoroughly and cover with mulch. Water until the soil is moist but not soggy. Cover with a two-inch layer of mulch to lock in moisture and prevent drastic temperature fluctuations. During the first year of growth, water whenever the soil dries out. After the plants are established, they can survive more irregular watering.
- Fertilize monthly. Once shoots sprout, fertilize every month until the plant fully matures.
- Harvest edible rhizomes. Certain plants—such as turmeric, ginger, lotus, and fingerroots—have edible rhizomes. Use them in seasonings, stir-fries, or soups. Some homebrewers even grow their own hop rhizomes to produce hops for beer.
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