How to Properly Grow Aquarium Carpet Plants

Written By: Chris (@shrimpery)

Before they became mass-produced, household carpets were a symbol of luxury, found only in the homes of the wealthy. Growing carpeting plants- the fine-leaved aquarium plants used to blanket the substrate of a tank- can seem similarly lofty to beginner hobbyists.

Even some more established planted aquarium keepers encounter challenges with previously healthy carpets suddenly turning yellow or melting. Despite their intimidating aura, I have found that, with the right materials and techniques, growing and maintaining a rich carpet is one of the easier aspects of the aquascaping hobby.

Choose the Proper Substrate

An enriched substrate, such as UNS Controsoil, is critical for helping most aquarium carpet plants reach their full potential and forms the foundation to a successful planted tank. The discrete clay granules are perfectly sized for the aquatic plants to form roots around without being excessively compact (which can lead to root ‘suffocation’ and anoxic areas).

These substrates retain macro and micronutrients for long amounts of time while allowing the aquarium plants continuous access to the nutrients as they grow and spread into a dense carpet. Although carpeting plant species can grow in a variety of substrates, such as larger-grained sand or gravel, these substrates are less preferred.

Enriched aquarium soil is also the easiest to work with when first planting the tank. The substrate should be at least 3 cm in depth; this allows adequate room for the plants to remain in place, without floating away, and for their roots to grow. The substrate can be made deeper as it approaches the back of the tank to create a sloping effect.

I also like to taper down the substrate’s depth to 0.5 cm or so at the very front of the tank (or even less if I use decorative sand at the front of the tank) for a cleaner look.

Use Proper Planting Techniques

Proper planting techniques are surprisingly critical to the long-term success of a planted carpet. I like to use tissue culture plants for all my carpets. It is best practice to fill the tank with water only after you finish planting, but it is easier working with a slightly moistened substrate than a bone-dry substrate.

It is also important to start with a lot more plants than you think you can reasonably get away with; the more plants per area, the less likely they will be to succumb to algae and the faster they will be to spread and fill in.

Break up the tissue culture plants into individual plantlets (or close to it) if possible, and try to plant them evenly, with no large clumps or uneven patches in the field. I like to use the UNS fine tip pinsettes to plant the plantlets deep enough into the substrate that a larger portion of the plant is buried beneath the surface than the part visible above the surface. This will help prevent the plantlets from floating up to the surface once you fill the tank.

Many aquarists have had success establishing their carpet using the dry start method (DSM), a technique that's growing in popularity in the aquascaping community. The DSM gives your plants more abundant access to the CO2 in the air as opposed to when they're submerged underwater (even with CO2 injection.) To learn more about the dry start method, check out the Dry Start Method Step by Step Guide. 

When you are ready to flood the tank, try to use a colander to break up the flow or else use airline tubing to slow the flow to a trickle; otherwise, you are in danger of undoing all your hard work.

Best Practices for Carpet Plant Care

For new tanks, it is important to keep up with water changes to prevent algae breakouts early on. A complete liquid fertilizer is also important but avoid excessive dosing, especially earlier on.

Finally, diffusing pressurized CO2 into the water column will result in a dramatically increased growth rate for otherwise slow-growing carpeting plants. Low tech tanks (those lacking CO2) can also grow carpeting plants, but the growth rate will be much slower than when CO2 is present.

Keeping trimming to a minimum for the first few weeks; under the right high light fixtures, carpeting plants will tend to spread horizontally more than vertically, filling in the gaps in the scape and making the carpet look less patchy.

Do not be alarmed if there is some melt initially; this is normal as plants adapt to new water conditions and parameters. New growth will quickly replace the melted portions if conditions are right.

Once the carpeting plants begin to pile on top of each other, it is time to trim. Curved aquascaping scissors are best for this purpose because they allow the user to cut the carpet at a right angle. I trim close enough to the substrate that any irregularities in carpet height are trimmed flush with the rest of the carpet.

For most carpeting plants, like Monte Carlo or Dwarf Baby Tears, you can use the floating clippings to fill in any remaining gaps in the carpet. This does not apply to Dwarf Hairgrass or similar species, however. In time, the carpet will become full and even.

Why is the Aquarium Carpet Suddenly Dying?

There are three common reasons why an established carpet can suddenly decline. Dramatic deteriorations, such an acute yellowing or melt, often stem from a sudden and drastic change in water parameters.

An example of this would be an aquascaper abruptly deciding to switch from relatively soft, remineralized RODI water to high pH, GH and KH tap water. Such a drastic shift can shock the plants and trigger mass melt as the plants struggle to adapt to the new conditions. A similar phenomenon can occur if extremely cold or hot water is used for a large-volume water change.

A more gradual decline of a carpet is apparent when the carpet’s leaves slowly become more yellow, or the part of the carpet adjacent to the substrate becomes atrophic and sparse. If the carpet is allowed to become too thick, the lowest parts of the carpet may have difficulty obtaining adequate oxygen and sunlight (or can simply become old and worn-out), resulting in a much-healthier upper portion. This process is especially pronounced if the substrate is aged and depleted of nutrients. A lack of nutrients is also often the reason for yellowing leaves.

The solution to all three of these issues is regular and consistent tank maintenance. Be sure to trim the carpet regularly (but not overly aggressively), keep water parameters as consistent as possible (making changes only gradually), and ensure adequate nutrition (replenishing enriched substrate as needed and dosing liquid fertilizer into the water column). With patience and consistency, any hobbyist can easily grow carpeting plants.

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