How to grow "HC Cuba"

Hemianthus callitrichoides (HC) 'Cuba' is one of the smallest ground creepers available in the hobby. It is popular as a carpet plant as its small size makes for a very fine carpet and contrasts well with other small leafed plants. HC Cuba is notorious for being one of the more difficult carpet plants to grow well in the planted aquarium. It is often referred to in the hobby as Dwarf Baby Tears, but this can easily lead to confusion as "Baby Tears" can also refer to a number of other plants.

A similar plant that is much easier to grow is Micranthemum Monte Carlo, with the difference being insignificant at a distance, especially in larger tanks. HC Cuba grows a little faster than Monte Carlo and has smaller leaves and stems. It is not as deep rooted as Monte Carlo and requires more frequent pruning. The HC Cuba plant needs much more CO2 to grow well compared to Monte Carlo. Both plants will crawl over rocks, but Monte Carlo will do this more aggressively.

Key Success factors

• Good CO2 levels - Click here for our CO2 guide.
• Adequate lighting - 40umols at substrate.
• Good planting technique - plant separate small strands rather than bunches.

Additional points:

• Lower temperature helps (< 26 degrees celsius)
• Possible to get good growth till 29 degrees or so. Exponentially harder above that. Tanks in the tropics with no chiller should avoid the hassle and just use Monte carlo.
• Fine, rich substrates help, but not a necessity.
• Not sensitive to KH; can tolerate higher ranges well (10+ dKH).

Tissue culture HC can be sensitive to ammonia/raw new aquasoils. Letting the tank mature for a couple of weeks before planting can help avoid melting issues.

For detailed steps on how to cycle a tank, click here.

Occasional trimming of HC down to the bone/substrate line to remove old growth will maintain a healthy carpet in the long term. Frequent trimming is necessary to prevent the carpet from becoming too thick and detaching from the substrate as the bottom layer deteriorates.

The HC Cuba plant grows quite fast when grown well; 1 tissue culture cup of plants will fully carpet a 1ft square area in less than 3 months.

Here, dwarf baby tears contrasts well with Bucephalandra Brownie Ghost.

Can I grow HC without CO2?

A common question we get asked is, can you grow HC Cuba plant without CO2? Growing HC Cuba plants without CO2 has a 95% failure rate. However, the remaining 5% will loudly advertise their success on Facebook and social media; a classic case of survivor bias. For example, HC cuba grows without CO2 using strong lighting and soil in the tank below.

CO2 is paramount to HC's success, it is a relatively undemanding plant otherwise. It is one of the plants which is sensitive enough to CO2 levels that it is useful to grow small patches of it in every tank as living CO2 indicators. It gets thinner with more spindly upward growth in low CO2 levels.

Classic CO2 deficiency in HC - thin stems, small new leaves, upward reaching stems and lack of horizontal growth.