Cultivating Hemianthus Callitrichoides Emersed
Iwagumi Padang, my planted tank, before kids.
Yes, that is a carbon dioxide canister pumping CO2 underwater!
"Hemianthus callitrichoides, sometimes known as ‘dwarf baby tears’, or more commonly as ‘HC’, was discovered by Tropica founder Holger Windeløv during an expedition to a small rocky stream east of Havana, Cuba; it was described in aquaristic literature for the first time in 2003. Since its introduction into the hobby, HC has become increasingly popular and a foreground plant of choice, making this once rare plant moderately easy to obtain." - Aquatic Plant Central.
I was first introduced to the world of aquascaping and Iwagumi through Takashi Amano. I find the field quite inspiring and complex. One of the first few aquatic plants I fell in love with were HC. As an initiate, I found that while there were a number of reading resources on HC available, they were not aggregated into a single coherent and comprehensive guide for these delicate beauties. This report is intended as a reference guide for anyone seeking to successfully replicate and cultivate a beautiful dense carpet of HC underwater.
Emersed (Dry Start) or Submersed?
I started cultivating HC emersed rather than submersed for the planted tank for three important reasons:
Relatively quicker for HC to densely carpet my scape emersed;
Allowed roots to establish itself deeper into the soil. This prevented floaters when the tank was first flooded, which was extremely frustrating;
Algae threat is minimized to zero as it allows HC to establish its dominance prior to flooding;
Tank and Lighting
The intended scape was housed in a tank and a good light source. I used a 20 liter (5.5 gallon) rimless tank with a 27W, 8000K power compact fluorescent bulb. This lighting arrangement works very well for a tank of this size and is sufficient for HC.
HC demands a substantial amount of light as it is a tropical plant, so I tried to replicate its natural habitat within an indoor setting for it to flourish (I am based in a continental climate zone). If you have to ask "do I have enough light?" - you probably don’t. At the very least, you should follow the two watts per gallon rule. It does not hurt to have more light. I used an 8000K lamp, which has the same spectrum as daylight.
There are three layers to the substrate scape. First, I layered the bottom with ADA’s Powersand Special which is basically a fertilizer type substrate with additional nutrients and beneficial microorganisms.
Next, I add a layer (at least 4cm depth) of ADA Amazonia 1, Normal Type. This is the main substrate. I prefer this over Amazonia 2 (ADA has recently updated the composition) as it does not crumble easily once flooded and has a more desirable chemistry (less acidic) with my source of freshwater.
Finally, I topped it off with Amazonia 1, Powder Type. The powder type has finer granularity which is much more suitable for HCs rooting.
I then added my hardscape. This included my choice of Seiryu stones. Once happy with the scape, I sprinkled a little more Amazonia Powder soil to cover any gaps and to make the hardscape seamless with the substrate (i.e. makes it look more natural).
This was the "fun" part. It will take time and patience to delicately plant your HC carpet. As with most gardening endeavors, it is easy to end up with a sore back.
How many pots of HC do I need?
I found that most aquatic plant suppliers will sell you HC in pots of rock wool. I started with about six or seven pots for a tank of this size. The more you have to start with, the faster it will carpet. I kept the pots in a humid Ziploc bag as I worked through planting.
Do I need to remove rock wool or can I just plant HC with it?
I removed it. It is a little extra work, but I found that as time goes by, I did not have to deal with excess dirt, rot, etc. and got better results.
I started by cutting off the excess rock wool at the very bottom with a sharp scissors. Next, I used tweezers to separate out the HC into smaller clumps or stems.
I wet the substrate so that it was uniformly moist as I found it easier to work with than a dry substrate. Using a mister and spray will help prevent flooding excess-watering.
Next, I individually planted these clumps/stems with a tweezer. Tweezers made it a lot easier, one’s fingers / hands are never small enough. When planting, I allowed about 5mm to 10mm of spacing between the clumps/stems. HC are no different than people as they need space to grow and flourish.
As the HC are from the tropics, they require high humidity when grown emersed. To control for this, I got a clear saran wrap and covered the top of the tank. This kept the humidity high and heat within bounds after a day’s worth of lighting. I was then done with the initial set up of the HC’s environment.
I set my lights on a timer for 8-10 hours a day.
The Daily Process
I then followed this daily routine which requires under 10 minutes a day for the next month or two:
- Morning wishes won't hurt your plant, probably relaxes you a little as well
- then unwrap the saran wrap cover
- then mist the whole terrain with water, including the hardscape
- I then would cover the tank with saran wrap
- I would inspect the tank without opening the saran wrap
- If the hardscape appeared dry, it is an indication of insufficient humidity – I would mist more and check that the saran wrap is sealed is tight!
- Get some rest
How Long Before I Get My Carpet?
Patience is key. The longer I waited, the more the HC established itself. It took about a month before I saw a dense carpet. I was not concerned that I did not notice any progress the first couple of weeks. I placed faith and trust in mother nature.
Misting excessively during the daily routine caused flooding in the soil. Flooding / excessive pools of water are not desirable as partially drowned HC will require CO2 supplements and will take longer to establish;
I kept the tank in a relatively warm place, avoiding cold droughts;
I avoided unwrapping the saran wrap at night as heat trapped from the photoperiod will dissipate. Heat is good, it encourages faster growth. So I confined all unwrapping / open air maintenance work on the tank to the mornings at the start of the photoperiod;
Every two or three days, the saran wrap will cumulate water from evaporation / humidity (dew). Replace the saran wrap so that layer of dew would not decrease light exposure;
The hardscape (stones) and glass walls of the tank are good humidity indicators. If they appeared dry, I would immediately mist more and ensure that the saran wrap is sealed tightly. I also considered increasing the misting dose every morning;
I refilled water in the mister with overnight tap-water. This reduced chlorine traces. I usually use water from my refrigerator’s filter. Alternatively, Brita-filtered tap-water is preferred to unfiltered tap-water.
Frequently Asked Questions, Concerns, and Fallacies
HC will suffocate if I do not leave a small gap in the saran wrap seal.
On the contrary, the HC did dry out over time and perished when I left a small gap in the saran wrap seal in one of my early experiments. The subsequent trials proved that the seal needed to be tight, air-flow is sufficient during the execution of daily misting in the mornings - sufficient to sustain growth and life until the next morning.
Is it okay to miss a day of the daily routine? They are plants after all and plants have slow reaction times.
I found that HC are quick to perish from neglect as they are extremely sensitive and delicate.
The soil seems a little flooded.
It took me awhile to practice a balanced level of daily misting. Excessive water will cause mold/algae to grow in the cumulated pools of water. This creates difficulty for HC growth in establishing roots and new stems. I used a syringe to extract excess cumulated water.
External resources related to this article:
- Planted Tank Forums
- My Planted Tank discussions of progress
- Hemianthus Callitrichoides on Aquatic Plant Central
- Aqua Journal Online
I thank Jordan Alexiev and Kimberly Phillips for assistance throughout my experiments. I have also learnt a lot from discussions with members of the PlantedTank forums. I am in no way affiliated with ADA.