How to grow Hemianthus callitrichoides 'Cuba'

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Hemianthus callitrichoides makes the perfect carpeting plant. George Farmer offers some advice on its care.

Name: Hemianthus callitrichoides ‘Cuba’

Common name: HC

Family: Scrophulariaceae

Origin: North America

Maximum height: Up to 3cm/1.2”

Width (each stem): 1cm+/0.4”

Temperature: 18-28°C/64-82°F

Hardness: Very soft to hard

pH: 5 to 7.5

Light demands: Medium

Growth rate: Slow-medium

Demands: Medium

What is it?

Hemianthus callitrichoides is one of the world’s smallest plants. It is relatively new to the hobby, but one of the most popular carpeting plants.

It is grown in nurseries emerged and can suffer from some die-off in early stages of adapting to underwater life.

It does best in a nutrient-rich substrate, preferably fine and smooth, so the delicate root structure can penetrate easily. It appreciates CO2 injection or a liquid carbon alternative and will struggle in aquariums without some form of carbon supplementation. Because this plant is so small and low to the substrate the tank must have good levels of circulation.  

How do I plant it correctly?

There are two main methods. The first is to separate the plant and rockwool from the pots then, using scissors, divide the plants/rockwool into 1cm/0.4” square portions. Plant them, including the rockwool, into the substrate and the plant should start carpeting after a week or so, depending on your set-up.  

A more time-consuming but very economical method is to pick off the tiny individual stems with tweezers and plant them separately, allowing only a few leaves to be exposed above the substrate. With this method it is possible to cover a relatively large area, but it is very painstaking.

Planting is best done in a moist substrate, but with no aquarium water added. When planting is complete, fill the tank very slowly to stop the plant from floating.

What’s the best way to encourage it?

Light levels do not need to be high and two T5s with reflectors or equivalent is plenty for most set-ups. More important is providing good levels of nutrients, especially carbon and nitrogen, and circulation.