Hygrophila polysperma, more commonly known as Dwarf Hygro or Indian Swampweed, is an easy-to-grow plant that grows best in low light and can tolerate poor water conditions. It’s an excellent foreground plant because of its dwarfing characteristics and fast growth rate.
If you’re looking to add some more color and variety to your aquarium, Hygrophila polysperma might be just the plant for you!
Also known as dwarf hygro, Indian swampweed, or myrio (depending on the country), this popular aquarium plant can give your tank some much-needed diversity with minimal effort on your part.
Here’s everything you need to know about caring for Hygrophila polysperma!
Origin and descriptions
Indian swampweed is a common aquatic plant in South and Central America. It can be found on every continent except Antarctica, and is typically used as an aquarium plant in many parts of Asia and Australia. Hygrophila polysperma, also known as dwarf hygro or Indian swampweed, was introduced to North America in 1988, where it has spread quickly due to its ability to reproduce rapidly. Due to its ability to overgrow native plants, it is considered invasive by most state governments in North America.
The hygrophila polysperma is a low-growing, perennial aquatic plant that looks very similar to hygrophila spp. A more accurate term for these plants is dwarf hygro since they are not true species of their own. Instead, hygrophila polysperma are hybrids of various species from genera such as Hygrophila and Limnophila.
These plants were bred in England in an attempt to create dwarf aquarium plants with quick growth rates and few roots. Though many breeders feel that Indian swampweed does not meet all of these criteria, it has been popularized among aquarists regardless, due to its beautiful coloration and delicate leaves.
Hygrophila polysperma, is one of many species belonging to the Acanthaceae family. These plants come from various tropical countries around the world, and their natural habitat is freshwater marshes. Because of their durability in water and tolerance for wet environments, Hygrophila polysperma has become a highly invasive plant species in ponds and other aquatic habitats worldwide.
In some areas, it has even been classified as an injurious weed. In addition to its versatility in regards to geographic location and environment, Hygrophila polysperma also features attractive green leaves with red-brown markings on each leaf’s margin. When planted en masse, they create beautiful decorative displays when allowed to grow undisturbed.
Hygrophila polysperma height
The dwarf hygro grows between 8 and 14 inches (20-35 cm) in height.
Hygrophila polysperma tank size
The smaller you keep your dwarf hygro, the more it will be more suited to a nano tank. It doesn’t need a lot of room. There are times that hygrophila polysperma will still grow out of control in even a 20 gallon aquarium, so be warned that it can grow quite large if it isn’t cared for properly.
The minimum recommended fish tank size to grow hygrophila polysperma is 10 gallons (38 liters)
Hygrophila polysperma propagation
You can propagate this plant by taking cuttings, and it is important to know how to get a cutting from your plant. If you have rooted your hygrophila polysperma, then take a cutting off of that, if not then you need to root one of your rhizomes. Take your cutting and look for a spot on it where there are new shoots coming out or where there are leaves coming out about 1/4 inch in diameter. You want that part to be very succulent and moist.
Cut above those parts of your cutting and dip into a rooting hormone to help speed up rooting. Then place them into some fresh clean water so they don’t rot, but also make sure they are sitting underwater because they will start to wilt pretty fast if they dry out completely. When they start to wilt, let them sit until their leaves become plump again before pulling them out. Once they have been replanted, wait for them to sprout and continue growing.
They should grow faster now that they are having their own roots than when you were holding them in your hand as a cutting! Also since there are already roots present now, transplanting should be easier than when you started with just a cutting.
Because of its small size, dwarf hygro is easy to hide behind other plants in your aquarium. It can be used as a foreground plant for angelfish or betta fish, since these species enjoy darting through dense vegetation. Be sure to provide some shade for smaller fish, however; otherwise, they may get stressed out in an environment that doesn’t allow them freedom of movement.
Hygrophila polysperma care
Under optimal conditions—high light, CO2 fertilization, and nutrient levels—dwarf hygro can double in size every 2-3 days under ideal lighting conditions. When conditions are less than optimal or when nutrients run low, dwarf hygro will grow more slowly or cease growing entirely until conditions become favorable again.
This is a very forgiving plant that makes an excellent choice for beginner aquarists with less than ideal lighting or those looking to fill space in their tanks. As long as it’s not shaded by other plants, it will generally grow quite fast and put out new leaves quickly. It doesn’t like low-light conditions but will tolerate medium light very well, provided sufficient nutrients are available. Plants grown emersed are significantly more colorful than those grown submersed because of reduced chlorophyll content.
Dwarf hygro will do well in medium to high light conditions. Avoid letting plants sit in direct sunlight for extended periods of time, as this may cause spotting, and leaves to yellow. To keep your plant looking its best, try to provide it with a minimum of 2 watts per gallon of fluorescent lighting or 1 watt per gallon of LED lights.
If growing your plant under low-light conditions, pruning may be necessary to achieve optimal growth rates. Under lower light levels, plants can become lanky and stretched out; therefore, trimming is done primarily to maintain bushy growth.
Dwarf hygros can be planted in substrate or soil. Substrate requirements vary slightly depending on the lighting. Under lower-intensity lighting, they can thrive in a substrate of 1 part peat to 1 part perlite with a pH of 5.8–6.5; under high light, use 1 part soil to 2 parts sand with a pH of 5.5–6.0 and nutrients added by dosing Flourish Comprehensive once every three weeks. Algae growth is common if plants are not getting enough carbon dioxide. If algae growth does occur, it’s best to remove it using an algae scraper and cleaning solution.
If you’re going to be keeping your Dwarf Hygro inside a tank, fertilizers can be an easy way to keep it looking healthy and vibrant. It’s recommended that you provide fertilizer once every two weeks, starting when you first add your plants and continuing until they are fully grown. There are many commercial aquatic plant fertilizers out there, but it’s also possible to make your own. One simple recipe is 1 tablespoon of Epsom salt dissolved in one quart of aquarium water.
Many fish stores will sell fertilizer made specifically for live aquatic plants; it’s important to note, however, that these contain slow-release pellets or tablets rather than liquid mixes like those designed for fish alone.
Dwarf hygros will tolerate a range of temperatures, but they prefer warm water. Keeping them between 75 and 85 degrees Fahrenheit is ideal. If you’re keeping them in an aquarium with more than one fish, it’s best to keep them at a steady temperature; fluctuating temperatures can stress out your dwarf hygros.
What should you do if your tank gets too cold? Use floating plants like water lettuce or bacopa, which act as heat sinks and can raise water temperatures by several degrees.
A good rule of thumb is to keep your hygrophila’s tank between 40 and 80% humidity. If you can’t keep up with it, consider adding a humidifier to increase moisture or even an overhead misting system that delivers water directly into your tank. You can also help your hygrophila survive dry conditions by floating its pots in water; just be sure to change it every few days. With proper care, a healthy dwarf hygro can live as long as 10 years.
How do you prune a hygrophila polysperma?
As with most aquatic plants, pruning a hygrophila is best done while it’s still young. We recommend trimming your plant when they reach around 6 to 8 inches tall, as you can often get multiple cuttings out of a single plant. If you want to use it in a small pond, however, you can prune even smaller and enjoy that same plant for several years before needing to replace it.
While most aquarium plants grow very slowly, hygrophilas are one of those rare exceptions that actually seem to double in size each week. Like most fast-growing plants, it needs lots of light and nutrients to stay healthy and happy. However, you don’t need to fertilize as much as with many other plants because its roots like oxygen and don’t have as much of a tendency toward nutrient accumulation.
USDA hardiness zones
This can be grown outdoors year-round in zones 10 and 11 ( (20-30°F)). In zone 9b and below, it is grown as an annual plant. In colder climates, grow it in a pot or indoors until early fall when nighttime temperatures do not go below 50°F. It may re-emerge from roots if left outside and will then take off growing in mid-spring as temperatures start to warm up again.
This dwarf hygro is one of a handful of aquatic plants that are known to be toxic to some aquarium species. Luckily, it’s not very potent and usually doesn’t bother less sensitive species like tetras or angelfish. However, if you do keep sensitive species like shrimp or dartfish, it’s best to avoid keeping hygrophila polysperma in your tank.
This plant also causes allergies to some people.
Pests and diseases
Like many other aquarium plants, hygrophila polysperma is vulnerable to infestation by snails and nematodes. Some hobbyists have had success removing these pests by simply rinsing their aquarium plants under running water from a hose. Others will pull any plants that show signs of infestation into another container of tank water and add aquarium salt to kill off whatever snails or worms that might be present.