Christmas Moss Care, Propagation, & Issues

Christmas Moss is a fast favorite for many aquarists, combining a dense leaf structure with thick growth. Despite the superficial similarities to Java Moss, Christmas Moss takes a bit of know-how to keep thriving.

Let’s get into it, and we’ll teach you everything you need to know about Christmas Moss Care, from common issues to aquascaping ideas!

christmas moss

Christmas Moss Fast Facts

Common Name: Christmas Moss

Other Common Names: n/a

Scientific Name: Vesicularia montagnei

Plant Type: Moss

Natural Habitat: Shaded Rivers and Creeks in Asia

Care Level: Intermediate

What is Christmas Moss?

Christmas Moss, or Vesicularia montagnei, is a green moss native to Asia. It’s spread across a large portion of the continent and you can find it everywhere from India to Japan growing along riverbanks and in creeks.

The plant displays tight growth, giving it a different visual from the superficially similar Java Moss. While Java Moss tends to grow in long, spindly strands you’ll find Christmas Moss tends to stay much tighter and denser.

Christmas Moss is a bit of a pain to keep and it’s a plant that many have failed with. You don’t have to, most of the errors come from assuming that it’s like Java Moss. Java Moss requires basically no care and it can even become a pest plant in established aquaria.

That’s not the case here, We have some specific requirements to keep the plant alive, and a couple more to make it thrive.

Christmas Moss is incredibly versatile provided it’s in the correct environment. It can be used as a carpet, to cover walls, as a driftwood accent, or clumped up to provide protection to fry. It’s one of the most common plants used to make driftwood “trees” in tanks as well, a look that’s very hard to achieve with many plants.

But… Christmas Moss is dependent on water conditions. 

Most aquarium plants are relatively plug-and-play for the experienced aquarium keeper, you just have to avoid newbie errors like iron deficiency and they’ll thrive.

Christmas Moss is sensitive to parts of the nitrogen cycle, temperature, and pH. It also requires the keeper to be on top of trimming, this handy little epiphyte will choke itself to death with no maintenance.

How hard is Christmas Moss to keep?

It’s not that hard to keep a thriving bunch of Christmas Moss, but it’s more difficult than true beginner plants. Read on, you only need to take a couple of extra steps to take advantage of the dense growth and intense green of Christmas Moss.

What Kind of Aquaria is Christmas Moss Right For?

Christmas Moss may not be a good fit for every tank. The biggest killer of new Christmas Moss is temperature. 

If it gets too high? The moss will melt away like a Crypt but if the temperature isn’t fixed it’s not going to grow back.

Christmas Moss is also a bad fit for jungle tanks. It requires trimming on a regular basis to stay attached to its anchor. If it gets too thick it will choke out the growth underneath and cause it to rot. Once it’s rotted enough you’ll have free-floating Christmas Moss ready to… be replanted.

In general, you want a tank with the following properties:

  • Aquascape- One that lends itself well to trimming is essential. Japanese-style nature tanks are the best example, but it can also serve well as a carpet plant in the front rows of a Dutch-style aquarium.
  • Moderate Temperature- You need to keep a moderate temperature for the moss to survive. Most people run their tropical tanks at the upper end of their fish’s preference and you may need to lower it. 75°F-78°F (24°C-26°C) is ideal, under 82°F (28°C) is essential.
  • High Tech- High tech tanks are ideal for Christmas Moss. That means high light levels and CO2 injection. Christmas Moss can grow very slowly in moderate lighting, but it’s not a good choice for low-tech tanks.
  • Clean Flowing Water- While ideal for all plants, you want to make sure that you have an established tank for Christmas Moss most of the time. I prefer to add it after a cycle. Likewise, you need moderate-to-high flow or the plant tends to stunt itself.

Christmas Moss isn’t quite as common as many plants, so you may have to find it online. In that case, do your research on the vendor as delayed shipping can leave you with a bag of brown, soupy water instead of a lovely clump of moss.

I don’t recommend that you use Christmas Moss as a drop-in for fry care, but it can work if you have the right conditions. Java Moss is a much better choice for that in my opinion.

Provided you’ve got the right temperature and adequate lighting it’s mostly practical matters that stop Christmas Moss from being perfect in every planted tank.

Care Overview

Christmas Moss isn’t overly demanding, but it does require more care than true beginner plants. If you have a little bit of experience keeping planted tanks and keep the following in mind you shouldn’t have much trouble with it at all.

Lighting

High light is the best for this moss. 3W per gallon (150 lumens per gallon) is a good starting point, a bit more won’t hurt.

Low-light environments don’t work for this plant. Anything under 1W per gallon (50 lumens per gallon) isn’t viable. The plant may “survive” but it will be very spindly and slow-growing. Sub in Java Moss for low-tech tanks.

Moderate lighting in the 1W-2W per gallon range will keep it alive and brightly colored, but it will slow down growth quite a bit. In my experience, it tends to become a lighter green color as well.

CO2 Injection

I strongly recommend using a CO2 system when growing Christmas Moss. Combined with high lighting, Christmas Moss will experience strong, dense growth.

You can also use a product like SeaChem Excel to add more available carbon to the water. It has a similar effect without having to tinker with a CO2 system, but I’ve found it’s inferior to actual CO2 for high growth.

Just be aware of which other plants are in the tank. Some beginner plants can turn into a nightmare with high lighting and CO2. Elodea densa, for instance, can end up growing an inch or more per day per stem, creating a situation where you need to trim every day.

Temperature

Christmas Moss is very sensitive to temperature. It will grow well in the 70°F to 80°F (21°C to 27°C) range but does best at 75°F to 78°F. If you get much under 70°F the plant will cease growing and may die after a prolonged period.

The real killer is going up. Anything over 82°F will cause the plant to melt. Christmas Moss, like Cryptocoryne sp., is prone to melting when water conditions change but if you’re over the upper limit for long you can kill the plant entirely.

In my experience, most people run their tanks on the warm side of things. 82°F-84°F is common, but it’s much too hot for Christmas Moss. Aim for the mid-70s and you’ll be in good hands.

Most plants are pretty adaptable when it comes to temperature but that’s not the case here.

If your Christmas Moss is dying, the first thing to check is the temperature. It’s the most common failure point for newbies trying to grow this plant.

pH and Salinity

Christmas Moss is relatively adaptable to pH, but it grows best in a pH ranging from 5.0 to 7.0. Acidic to neutral is ideal for the rapid growth of this plant.

It will grow in conditions up to 7.5 but may have trouble adapting outside of that range. Likewise, very hard water can also slow down the growth of the plant but it’s usually not a killer.

Salinity is a no-go for Christmas Moss. Even at ich maintenance levels it will cause problems. Ich treatment, in general, is a huge problem for Christmas Moss as the usual measures involve adding salt and maintaining a high temperature.

Make sure to quarantine fish going into a tank with Christmas Moss. A case of Ich may cost you your plant.

Fertilizers

Like all aquatic mosses, Christmas Moss is an epiphyte. In other words, it takes its nutrients from the surrounding environment rather than directly from the substrate.

Aquatic plants need micronutrients added to the tank on occasion, and this one is no exception. The neat part is that you can use a standard liquid fertilizer even if you’re using the plant as ground cover. No need to mess around with root tabs.

Christmas Moss isn’t prone to any nutrient deficiency in particular, so a full spectrum fertilizer like SeaChem Flourish is perfect.

Maintenance

Christmas Moss has a weird habit of choking itself if it grows too thick. You need to make sure that it doesn’t do so with regular trimming.

In a high-tech tank, you’ll most likely have to trim once per week or so, possibly more if you’re keeping a closely trimmed carpet.

The problem is easy to identify: if the bottom of the plant is turning brown while the top remains a vibrant green you need to trim it back.

It’s best not to let it get to that point.

Propagation

Rip off a chunk and put it somewhere else.

Aquatic mosses are easy to clone, all you have to do is separate a bit from the main plant. Propagation of Christmas Moss is never a problem unless you transfer the moss to a tank with unfavorable conditions.

Make sure you clean up any Christmas Moss that ends up floating free. In an ideal tank, even a single strand can cause growth where you don’t want it.

Common Issues and What to Do About Them

Christmas Moss has a few common issues detailed above, and a couple we haven’t discussed yet. In general, emergent problems are easy to handle as long as you know what to do.

The following issues and their solutions will keep your plant alive in most situations:

  • Browning at Bottom- The plant has grown too thick, trim it back and observe the brown bits. If they rot you may lose your hardscape attachment point.
  • Melting After Acclimation- Christmas Moss may melt back if your water is different than the water it came from. It should recover quickly. Down the road, if it begins to melt you may need to lower the heat in the tank, check the temperature!
  • Yellowing and Slow Growth- In high-tech tanks, plants can sometimes outstrip the nutrients in the water column. Yellowing plants usually means the tank needs a dose of iron but it can be related to other micronutrients. Liquid fertilizer once a week will keep this from happening.
  • Browning All Over- Algae growth can sometimes choke Christmas Moss. Brown diatomic algae, in particular, can form dense coats over the plant. Hard water and high nitrates are both causes of brown diatomic algae. If you’ve got brown coating things in your tank, inspect your Christmas Moss regularly.
  • Trapped Debris- If you lack inverts in your tank, you may have trouble with Christmas Moss attracting debris. My personal solution is to just throw in a dozen Cherry Red Shrimp, but you can also use a small gravel vac. Agitate the plant to release the debris, rather than using the vacuum directly, for the best results.

How to Use Christmas Moss in Aquascaping

Now that we’ve gotten care out of the way, let’s talk about the fun stuff!

Christmas Moss is one of the most versatile plants available for aquascaping. Attachment points are the main concern when you’re using them.

How you use it is up to you, but here are some general ideas to get you started.

Light and Growth Formation

Like a lot of aquatic plants, Christmas Moss will grow differently depending on the light levels in your tank. It’s an important consideration when you’re deciding on where it goes.

Christmas Moss will grow horizontally with high lighting, but low lighting will cause it to grow vertically.

This can limit your options depending on the lighting in your tank. I recommend at least 3W per gallon (150 lumens per gallon) for using it as a carpet plant.

Hardscape Attachment

Attaching moss to your hardscape is easy enough. There are several methods available to the budding aquarist and all of them work well with Christmas Moss.

  • Superglue- Using a cyanoacrylate super glue is ideal for attaching this plant to rocks, since other methods often fail before the plant is fully established. Make sure the glue is 100% dry before you place the rock into the tank, the solvents that dry out of the glue are highly toxic. Use aquarium glue if you’re not familiar enough with superglue to pick one that will be fish-safe when dry.
  • Thread- Thread is my preferred method for attaching plants to driftwood. The idea is to use a cotton thread that will rot away when it’s in the water long enough, it just needs to last until the plant is attached. I use dark green or black thread and simply wind it tightly around the driftwood and moss 10-15 times before tying it off with a double knot.
  • Fishing Line- If you find that thread fails you, but you don’t want to mess with glue, you can use a fishing line to attach the plants. A lightweight (5-10lbs) line will hold until the plant is established, all you need to do is tie a firm knot. You can remove the line a few months down the line once the moss is fully attached.

The key here is to get a hold that will last for a few months. Christmas Moss will grow “into” hardscape items and eventually the attachment point is redundant. A cotton line can be allowed to rot, but you’ll want to remove the fishing line sooner or later.

Don’t try to trap the Christmas Moss under a rock or driftwood. This method does work for some plants, like Anubias sp., but Christmas Moss will simply rot underneath the cover and become untethered in a week or so.

Attachment to hardscapes can be as simple or complex as you like. A single driftwood stick may grow with moss on it, or you can make a complex arrangement that covers the entire back of the aquarium.

One of the coolest uses for Christmas Moss is to make small “trees” using driftwood sticks. You simply attach the Christmas Moss to the upper portions of the stick and then trim it into shape. It takes a lot of work, but the effect can be spectacular in the right tank.

Christmas Moss will attach to almost anything, your creativity is the only limit in this arena.

Use as a Carpet Plant

Christmas Moss makes a great carpet in tanks with high lighting and CO2 injection, where its dense growth will run along the floor of the aquarium instead of reaching upwards.

The problem for most aquarists is where to begin attaching the moss to the floor. After all, Christmas Moss likes to die off when choked and that will leave the plant free-floating when the choked bits finally rot.

There’s a much easier way than just fighting your substrate: use stainless steel or plastic mesh. Either is fine, but stainless steel is more durable and works better as a weight.

The procedure is as follows:

  1. Cut mesh to size, it should cover most of the area you want to be carpeted.
  2. Cut a second piece of mesh the same size and shape.
  3. Sandwich your Christmas Moss starter in between the two cut pieces of mesh
  4. Fix the two pieces of mesh together. String or small zip ties both work well, the latter can be hidden under the substrate along the edges.
  5. Carefully place the mesh in the tank. Don’t cover it with the substrate. You can work it gently down so the mesh is less visible but do not cover the moss.
  6. Care for the Christmas Moss as normal, it will fill in the mesh and a little bit beyond.

As long as your equipment and water parameters are right, the Christmas Moss will grow in. It tends to start slowly but once it’s acclimated growth will speed up.

In tanks with lower lighting and no CO2 this may not work, and if it does you’re looking at very slow growth. I recommend picking another carpeted plant more suitable for low-tech tanks, I’m partial to Dwarf Saggitaria in that situation. If a moss carpet isn’t negotiable, you can follow the procedure above with Java Moss.

Carpets need to be trimmed regularly, if the plant inside the mesh dies and rots the plant may escape. Keep it under an inch and you’ll enjoy better results, most Japanese-style tanks utilizing Christmas Moss keep it trimmed even shorter.

Carpets present their own problems for the aquarist, but the main problem is detritus. A cleanup crew of snails and shrimp are essential in tanks that contain carpet plants.

Vivarium Use

Christmas Moss can grow emersed, which makes it a great moss for vivariums.

You’ll want to plant it and attach it just like it’s underwater. Humidity levels in the tank should be around 100% for the best results, but if you drop occasionally that’s fine. Christmas Moss is decently drought tolerant but it will go brown and dormant if it’s not receiving enough water.

Christmas Moss tends to grow slower when it’s out of water. If you want to use it for a background (ie: in a dart frog vivarium) you’ll want to use a lot of clones. Try placing the patches with around 2” of space between them.

I prefer glue for emersed attachment. Any super glue will do in this case, since you don’t have to worry about anything leaking into the water column.

With A Touch of Care, Amazing Results!

Christmas Moss isn’t the easiest plant to grow, but if you’re willing to put in a little bit of work it can be very rewarding. It’s one of the most versatile plants available to the aquarist and a fast favorite among those with an aquatic green thumb.]

Just watch the temperature and give it a shot! You’ll have a thriving plant in no time.