Whorled pennywort

Whorled pennywort key facts

Growing Difficulty

Beginner-friendly

Lifespan

Perennial; keeps spreading by rhizomes

Size

About 3–10 cm tall in aquaria; up to about 40 cm outdoors

Watering

Benefits from moderate CO2; grows without fertiliser outdoors

Lighting

Likes strong light; outdoors, give it a sunny spot.

CO2 & Fertilizer

In aquaria moderate CO2 helps; outdoors it grows without fertiliser.

Water Temperature & Quality

Does best in soft, slightly acidic water; also grows in pots of moist soil.

Substrate & Attachment

Plant in the substrate or let it float; outdoors it suits marginal pots and biotopes.

Trimming & Propagation

Its rhizomes run freely; cut back excess growth. Pieces of rhizome root readily.

Cautions

Listed as a Priority Control Alien Species. Never dump or plant it in rivers, ponds or rice fields, prevent overflow from containers in heavy rain, and dry cuttings before binning them.

About Whorled pennywort

Whorled pennywort is a beginner-friendly perennial aquatic plant with round leaves that spreads via rhizomes, growing 3-10cm in aquariums and up to about 40cm outdoors.

7 things to know before growing Whorled pennywort

1. 1Give It Plenty of Light

   Whorled pennywort thrives in bright conditions, so place aquarium specimens under strong lighting and grow outdoor plants in a sunny, boggy spot or biotope. It tolerates strong direct sun well, making it forgiving for beginners.

2. 2Keep It Consistently Moist

   As a bog plant, it needs its substrate or soil to stay consistently damp rather than drying out. Since it grows equally well submerged or emersed in an aquarium, care stays simple as long as you avoid letting it dry out completely.

3. 3Use a Water-Retentive Substrate

   This plant does better in water-retentive substrates like aquasoil or paddy soil than in coarse gravel. Because its rhizomes spread through the substrate, a reasonably thick layer helps it root in securely.

4. 4Repot Before It Gets Crowded

   Its rhizomes spread outward quickly, so dividing or repotting once growth starts looking crowded keeps your layout tidy. You can also propagate it simply by cutting off a length of rhizome and replanting it elsewhere.

5. 5Growth Shifts With the Seasons

   Growth is most vigorous during warm weather, when the rhizomes extend quickly. It slows down in cooler months, so adjusting how often you trim it to match the season works well.

6. 6Keep It Contained Outdoors

   In outdoor bogs or biotopes, the rhizomes can spread further than expected. This plant (Hydrocotyle verticillata var. triradiata) is listed as a "priority control" alien species on Japan's Ministry of the Environment list of invasive species, and it has naturalized in many parts of Japan. Never dump or plant it in rivers, ponds or rice paddies, keep containers from overflowing and washing plants out in heavy rain, and dry out any trimmings before throwing them away with household waste. Note that it is a different species from Brazilian pennywort (H. ranunculoides), which is a designated invasive alien species.

7. 7Pick Plants by Leaf Color and Firmness

   When choosing a plant, look for leaves that aren't wilted and have deep green color with good firmness, which points to healthy subsequent growth. Plants with sturdy leaf stalks and several shield-shaped leaves tend to establish more easily.

Frequently asked questions about Whorled pennywort

Q.Is whorled pennywort suitable for beginners?

A.Yes, it's considered an easy plant for beginners to grow. It adapts to both submerged and emersed conditions, and problems are rare as long as it isn't allowed to dry out completely.

Q.Can it be grown outdoors, not just in an aquarium?

A.Yes, since it's a bog plant, it also grows well in damp outdoor soil or biotopes. Outdoors it tends to grow larger than in an aquarium, sometimes reaching around 40 cm.

Q.How big does it get?

A.In an aquarium it typically stays compact at around 3 to 10 cm tall, while in an outdoor bog setting it can reach roughly 40 cm. Its final size depends a lot on the growing environment.

Q.What should I do if it spreads too much?

A.If the rhizomes have spread further than you'd like, cutting them back and dividing the plant helps tidy up the layout. The cut sections can be replanted within your tank or container, but never dump surplus plants into rivers or ponds; dry them out and dispose of them with household waste.

Q.Can it grow both submerged and above water?

A.Yes, as a bog plant it grows well both submerged and emersed. That flexibility means it can be kept in an aquarium or in an outdoor wetland setting, giving you plenty of placement options.

Handy Growing Tools for Whorled pennywort

Learn more about Whorled pennywort in the encyclopedia

More in this category