How to Care for Water Wisteria (Hygrophila difformis)

Water wisteria (Hygrophila difformis) is a very popular aquarium plant in the hobby because of its lacy leaves, bright green color, and rapid growth. While its care requirements are easy, this species is very prone to melting and losing its leaves when you first purchase it (similar to melting Cryptocoryne plants). Find out our best tips and tricks for planting your new wisteria, getting past the melting phase, and propagating it to grow new plants.

What is Water Wisteria?

This aquatic stem plant is native to countries ranging between India and Thailand and can easily grow up to 20 inches tall (51 cm) and 10 inches across (25 cm). (At greater heights, light has difficulty reaching the base of the wisteria and thus the bottom leaves may begin to thin out.) Many people use this bushy species as a background plant in their fish tanks, but you can also plant it in the foreground or midground if you want to cut it shorter. As a fast-growing plant, it is often used to consume nitrogen waste compounds in the water and outcompete algae growth. However, if you do not provide enough lighting or liquid fertilizer, it will let you know by melting away from starvation.

Why does my new water wisteria not look like the pictures online?

Like many live aquatic plants, wisteria is often grown in commercial plant farms with its leaves and stems out of water and roots in the water. This method is used for growing plants faster, bigger, and free of algae and pests. Emersed-grown plants (or plants grown above the water surface) generally have thicker stems that are built to withstand gravity and broader leaves that can absorb carbon dioxide directly from the air. Wisteria produces emersed leaves that look like strawberry leaves – featuring a roughly 1.5-inch (4 cm) oval shape, grooved veins, and slightly jagged edges.

Emersed-grown wisteria leaves

Once you place the wisteria in your fish tank, it must drop its old, emersed leaves and grow new, submersed leaves (or leaves that are grown completely underwater) that are capable of drawing carbon dioxide and other nutrients from the water. Submersed leaves are usually thinner, narrower, and more delicate in appearance. Wisteria produces submersed leaves that look drastically different from their emersed growth, which can lead to a lot of confusion, but they are in fact the same species that changes its leaf appearance to adapt to different environments. When grown underwater, wisteria has bright green, feathery fronds that can reach 4 inches (10 cm) across. Its bushy appearance can be used to add an interesting visual texture to planted tanks and is perfect for hiding fish fry or shrimp.

Submersed-grown wisteria leaves (on the right)

What is the difference between water wisteria and water sprite? Both wisteria and water sprite (Ceratopteris thalictroides) have delicate, lacy leaves that look quite similar, but when compared side to side, water sprite has thinner, more needle-like leaves. Water wisteria is a stem plant that can produce long branches all along the stem, whereas water sprite is a fern species that creates new shoots from a central point at the base of the plant.

Submersed-grown water sprite

How to Plant Water Wisteria

1. Carefully remove the stems from the rubber band, bundle, or rock wool inside the plastic pot.
2. Trim any stems or leaves that were damaged during transportation.
3. Using your fingers or tweezers, plunge the base of each stem as deeply as possible into the gravel or substrate.
4. Plant each stem separately approximately 1-2 inches (2.5-5 cm) apart so they have room to develop roots and become anchored.

If you have fish that like to dig in the substrate, protect the newly planted stems by surrounding the patch of wisteria with a ring of rocks, wood, or other decorations. Alternatively, wisteria can also be grown as a floating plant where it simply rises to the water surface and develops lots of hanging roots all along the horizontal stem.

Planting water wisteria in the gravel with tweezers

Why is My New Wisteria Plant Dying?

After you plant the wisteria, expect it to look good for the first couple of days. Then halfway through the first week, emersed leaves will start turning yellow and then brown, especially near the bottom of the stems. Once the leaves are brown, you can remove the leaves if you wish to avoid having excess rotting organics in your aquarium. If your wisteria is lacking in light and/or nutrients, the stems may turn brown and melt away. Cut off the brown, soggy stems and replant the healthy green parts of the wisteria. Then add more lighting or fertilizer as needed.

Emersed-grown leaves at the base of the stem tend to brown and melt off first.

How to Convert Your Wisteria from Emersed to Submersed Growth

The conversion phase can take anywhere from a couple of weeks to a couple of months, depending on the fish tank’s light, nutrient, and carbon dioxide (CO₂) levels. For a low tech tank with dimmer lighting and no CO₂ injection, it may take about a month for the first submersed leaves to appear. To speed up this process, use medium to high lighting for the aquarium. Place the wisteria directly under the light and make sure other plants don’t cover it with shade. Also, provide lots of nutrients in the water column using an all-in-one liquid fertilizer, and add a mineral supplement if you have soft water with low amounts of GH. CO₂ injection is not required but will greatly shorten the conversion time since it provides more building blocks for the wisteria to use.

If you plant the wisteria in the substrate, try not to move it around. Every time you disturb the ground, it stops growing for a period of time while readjusting to the new location. Also, make sure the stems are not too tall and growing out of the water, or they may develop more emersed leaves instead of submersed leaves. If you are having trouble getting your wisteria to convert, try floating some stems where they can collect more light and CO₂ at the water surface. Once they start growing a decent amount of roots, then you can try planting them in the substrate again. Finally, keep the water parameters, lighting, and fertilizer at stable levels because wisteria easily melts when its environmental conditions are volatile.

Pot of submersed-grown wisteria

How to Propagate Water Wisteria

Once the plant becomes well-established, it can start growing like a weed at a rate of 0.5-3 inches (1-8 cm) per day. To prevent it from blocking all the light and outcompeting other plants, cut off the top half of the stems and replant the trimmings to propagate the wisteria. You can leave the bottom half of the stem in the ground, and it will eventually grow new leaves from the tip. However, if the bottom half is too “leggy” and lost most of its leaves during conversion or from lack of light, many people choose to remove it and plant the top half of the stem in its place. If the wisteria is floating, don’t let it cover more than 50% of the water surface, or else it may shade out other plants and cause stagnant, oxygen-deprived water.

The emersed leaves lower on the stems have developed holes and algae growth, whereas the new, submersed leaves at the tips of the stems are healthy and bright green. When several inches of submersed leaves have grown, you can cut off the healthy tips and replant them to replace the old, emersed-grown sections.

Best of luck with your new wisteria. If you’re looking for more articles on live aquarium plants, make sure to check out the Planted Tanks section of our weekly blog.