| Common Name(s) | Downoi |
| Scientific Name | Pogostemon Helferi |
| Origin | Thailand |
| Ease of Growing | Easy |
| Aquacape | Foreground |
| Height | 5-10 cm |
| pH | 6-7.5 |
| Temperature | 68-86°F (20-30°C) |
| Growth Rate | Medium |
| Propagation | Side shoots |
| Light Requirement | Medium |
| CO2 Requirement | CO2 is not required but dosing up to 6-14 mg/L can help growth rate. |
Pogostemon helferi, also known as Downoi, is an aquatic plant that originates in Thailand. Due to its unique wavy leaves and ease of care, they’ve become a popular aquarium plant. They are often used as a foreground plant in various aquascapes.
Pogostemon helferi has been known in the scientific community for over 120 years. When it was first discovered in Burma and Thailand, scientists found it around the edge of streams. This explains why it grows so well when attached to limestones. However, the plant was introduced to the aquarium hobby in 1996 by Nonn Panitvong and Arthit Prasartkul. Since then, the plant has been used in various aquascapes.
One of the reasons why this plant is so appealing to aquascapers is because of its adaptability. In their native habitat in Thailand, Pogostemon helferi live in various environments. Throughout the seasons, and depending on the amount of rainfall, the plant may grow as a emersed plant or a submersed plant.
Even though Pogostemon helferi hasn’t been in the aquarium hobby for very long, it has quickly become a favorite among many aquascapers. Considering its unique appearance, versatility, and the ease of care, it’s understandable why so many hobbyists want to incorporate the plant into their aquascapes.
Pogostemon Helferi Care
Pogostemon helferi can be planted in the substrate of an aquarium and will produce a beautiful low star-shaped growth pattern if given lots of light. Even though it will still grow in low light environments, the growth will not be as robust. The optimum parameters for Pogostemon helferi consists of a pH of 6-7.5, temperatures of 68-86°F (20-30°C), and high levels of nutrients. Nutrients can be provided in the form of root tabs or liquid fertilizers. For best results, root tabs should be inserted into the substrate regularly. Adding CO2 injection will help it grow more quickly and more robust as well. Dead leaves should be clipped off, rather then letting it rot on the plant. If the old leaves are allowed to stay on the plant, it could stunt new growth.
Water changes will benefit the plant, so it should be done regularly. Replacing a lot of water in the tank can cause drastic changes in the water parameters, so this should be avoided. If there are fish in the same tank, high volume water changes can be unsafe for them as well. Instead, small water changes that are done frequently are better. For example, 10% water changes on a weekly basis or 20% water changes every other week can be beneficial. When adding new water into the aquarium, make sure that the water parameters are similar to the existing water in the tank. This includes the water pH and temperature. If the parameters are drastically different, even small water changes can become dangerous.
Regarding the lighting requirements for Pogostemon helferi, they need a lot of light. The aquarium light should be kept on for 8-10 hours a day to ensure proper growth. They should be planted in an area within the aquarium that would allow them to absorb the light as well. Tall plants that have overhanging growth may block the light, and this should be avoided.
Pogostemon helferi is very easy to grow, and exceptionally hardy once it is established. Therefore, this plant is great for both beginners and advanced hobbyists.
Planting Pogostemon Helferi
In order to prepare Pogostemon helferi for planting, it should be acclimated to the new environment. The plant is usually sold in pots. This pot can be planted directly into the aquarium substrate. This will allow the plant to get used to the new water parameters with minimal disturbance, especially to the root system. Once the plant is well-acclimated to the new environment, it can be taken out of the pot. Gently separate the plant into individual stems. Be careful not to damage the leaves and roots.
Pogostemon helferi can be planted directly into the substrate. If they are planted approximately 2 inches apart in the substrate, the plant can create a carpeting affect as it grows. Under optimal conditions and good lighting, the plant will grow very dense.
In addition to planting in substrate, Pogostemon helferi can be attached to hardscape such as porous rocks and driftwood as well. Until the plant is able to anchor itself to the surface of the hardscape, it can be attached to it with aquarium-safe glue or a string.
Since they are small plant, they can be planted in various aquariums, including nano tanks. Keep in mind that regular trimming is important, especially in a small environment.
Problems Growing Pogostemon Helferi
Often in low light conditions, Pogostemon helferi will begin to stretch towards the top of the tank to reach more light. This will cause the plant to appear less robust and dense. To prevent this, add more light or adjust the light duration.
If the plant is not growing or growing very slowly, there may be a lack of nutrients. Keep in mind that nutrients in the water and substrate must be supplemented regularly. The nutrient level will decrease naturally as the plant absorbs it. Some of the nutrients may be lost during regular water changes as well. Monitoring their needs regularly, and supplementing them with aquarium plant fertilizers will ensure that they maintain their growth rate.
Pogostemon helferi may start to melt if there is a drastic change in the water parameter. This is why the plant often melts when they are placed in a new tank. It doesn’t necessarily mean that there is something wrong with the water parameter. It may simply mean that the water parameter is different. In order to help acclimate plants to a new environment, it is best to disturb the plant as little as possible. If the plant was acquired as a bunch or in a pot, the plant should be separated only after it is well acclimated. If the plant does melt and appear to be dying, keep in mind that it is very likely that the plant will regrow, especially if the root system is healthy.
Propagating Pogostemon Helferi
Pogostemon helferi propagates through small side shoots, each one developing its own roots. If the side shoots are left alone, it will establish itself nearby. If you wish to replant it in a different location, it can be cut off from the mother plant as well.
When the plant is grown emersed, Pogostemon helferi will develop small flowers that produce seeds. This is another method of propagation. New plants can be grown from seeds, and these plants can be grown as either an emersed plant or submersed plant.
Keeping Fish with Pogostemon helferi
It is very possible to keep Pogostemon helferi with fish. Many fish species, especially herbivorous fish, may nibble on the plant. However, this is usually not an issue for an established plant. Even if it is nibbled on, it can usually recover quickly.
Larger fish such as Oscar fish may uproot the plant, and that may cause damage to the plant. Otherwise, well-established plants are usually not affected by smaller fish.
Pogostemon Helferi Red
Pogostemon Helferi Red is a color variant of the Pogostemon helferi plant. As their name suggests, they have a red hue to their leaves. They are rare in comparison to Pogostemon helferi, and they can be quite difficult to find.
The care requirement of Pogostemon Helferi Red is similar to Pogostemon helferi. Adequate lighting, good nutrients, and CO2 injection will enable robust growth. The red coloration provides a great accent to many aquascapes. Instead of placing the plant in the center of the aquarium, the red accent is often placed towards the side of the tank. Its frilly leaves provides a beautiful texture to the entire aquarium.
Finding Pogostemon Helferi for Sale
Even though Pogostemon helferi hasn’t been in the aquascaping hobby for long, it is has become a very popular plant over the years. In local fish stores, they may be labeled as Downoi plant as well.
While they may not be available in every local fish store in your area, there are plenty of online retailers that carry this plant including Amazon. In most local fish stores, they are available for $10-20 each, which is a relatively reasonable price.