If you're new to plant care, you might be surprised to learn that some of the most beautiful plants don’t start with seeds or cuttings—but from something hidden beneath the soil called a corm. Often mistaken for a bulb or tuber, a corm is actually its own unique kind of underground growth structure, and it plays a powerful role in plant propagation and survival.
At Urbane Eight, we help new and experienced growers alike understand their plants from the ground up—literally. In this beginner-friendly guide, we’ll explain what corms are, how to find them, how they grow into new plants, and exactly how to plant and care for them.
What Is a Corm?
A corm is a swollen part of a plant stem that grows underground. It stores food and energy to help the plant grow new leaves, roots, and stems—either during its regular life cycle or after a dormant period (like winter).
Unlike bulbs, which have layers like an onion, corms are solid on the inside. And while they might look like small rocks or roots covered in dirt, they are actually living structures full of potential.
Corms are not just part of the plant’s survival system—they can grow into entirely new plants on their own.
What Plants Grow From Corms?
Some of the most popular garden and houseplants grow from corms. If you’ve grown any of these, you’ve likely had corms in your soil without realizing it:
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Gladiolus
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Cyclamen
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Caladium
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Watsonia
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In many of these plants, especially Alocasia, corms appear as small round growths near the base of the plant or slightly deeper in the soil.
How to Find Corms in Your Plant
If you suspect your plant grows from or produces corms, here's how to locate them:
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Gently remove the plant from its pot. Loosen the soil carefully to avoid damaging the roots.
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Look around the base of the plant and root system. You’ll often see small, firm, round nodules either attached to the roots or sitting just below them.
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Feel for firm tissue. Corms should be solid when gently squeezed. If they’re soft or mushy, they may be rotten and shouldn’t be used.
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Some plants form clusters of corms, with smaller "cormlets" growing alongside or beneath a larger "mother" corm.
It’s completely normal for corms to be coated in soil or have a papery outer skin.
How Corms Can Grow a New Plant
Each healthy corm has the potential to become a full plant on its own.
With moisture, warmth, and time, a corm will begin to sprout new roots and eventually a stem or leaf. This makes them a natural way to propagate (multiply) your favorite plants—no cuttings or seeds required.
Many plants, like Alocasia, naturally produce corms as they mature. These can be collected and replanted to expand your plant collection or share with others.
How to Prepare Corms for Planting
Before you plant corms, it’s important to clean and inspect them:
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Rinse or soak the corms in room-temperature water for a few minutes. This removes old soil and reduces the chance of pests or fungus.
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Peel away any loose, papery skin, especially if it’s blocking the sprouting point. Some corms—especially taro—have a hard, shell-like outer coating that should be gently peeled back to reveal the inner tissue.
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Check for rot. Discard any corms that feel hollow, mushy, or have an unpleasant smell.
Corms don’t need to dry out before planting, but they do benefit from starting clean and hydrated.
Choosing the Right Substrate
Corms grow best in light, airy, and moist—not wet—substrates that allow for airflow and prevent rot. Before planting, always moisten the substrate so it feels like a wrung-out sponge.
Here are a few popular planting options:
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Perlite: Offers excellent drainage, ideal for humid environments. Caution: perlite dust can be harmful—wear a mask when handling it dry.
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Sphagnum moss: Holds moisture and supports early root development. Needs ventilation to avoid mold.
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Coco coir: A sustainable, spongy medium that retains moisture without becoming soggy. Good for most tropical corms.
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Stratum (aqua soil): A nutrient-rich, soil-like substrate often used in semi-hydro setups. Ideal for growers wanting structured root support.
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Soilless potting mix: Easy and accessible. Choose one with added perlite or bark for better drainage.
Avoid traditional heavy garden soil—it retains too much water and can suffocate developing roots.
How to Plant Corms
Once cleaned and prepared, follow these steps:
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Fill your container with pre-moistened substrate.
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Place the corm with the pointed end or sprout facing up. This is where the stem will emerge. The flat side will develop roots.
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Plant the corm about 1.5 to 2 times its height deep in the substrate.
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Cover the container with a humidity dome, clear plastic lid, or place it inside a sealed container to simulate a mini greenhouse. This helps trap warmth and moisture.
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Ensure airflow. Fully sealed environments without ventilation can encourage mold or rot. Leave a small opening or ventilate daily.
Set your container in a warm space with bright, indirect light. Avoid direct sun at this stage.
How Long Do Corms Take to Grow?
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Larger corms may sprout within 1 to 3 weeks.
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Smaller cormlets can take 4 to 6 weeks—or even longer—before showing signs of growth.
Growth begins with root formation, followed by the emergence of leaves or stems. Avoid disturbing the corm during this time, even if progress seems slow.
Do Corms Affect the Mother Plant?
Yes. As new corms or cormlets form, they begin to draw energy from the parent plant, which can lead to:
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Fewer or smaller leaves
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Delayed growth
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Reduced vigor in the main plant
To keep your mother plant healthy, remove mature corms at the end of the growing season or during repotting. These can be planted separately to grow new plants.
How to Store Cormlets for Later
If you don’t want to plant corms right away:
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Let them dry for 1 to 3 days in a cool, dry area.
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Store them in a paper bag or a box filled with dry vermiculite or sawdust.
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Keep them in a dark, ventilated place away from extreme cold or humidity.
They’ll remain dormant until you’re ready to plant them in the next growing cycle.
Corm Care After Planting
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Water sparingly until roots are established. The substrate should remain moist, not soggy.
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Provide bright, indirect light once growth begins.
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Fertilize lightly every few weeks using a balanced, diluted plant food once roots and leaves are visible.
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Monitor for mold or pests, especially if using moss or humidity domes.
With the right setup, your corms will grow into strong, healthy plants in no time.
Ready to Grow With Corms?
At Urbane Eight, we supply everything you need to start your journey—from premium corm-grown plants to substrates, tools, and propagation kits. Whether you’re experimenting with Alocasia pups or sprouting your first Crocus, corm growing is an accessible and rewarding process for any level of gardener.
Discover what’s growing beneath the surface—only at Urbane Eight.