How to grow Hemianthus glomeratus ; Pearlweed/Baby tears/Hemianthus micranthemoides

Hemianthus glomeratus has been in the hobby for a long time and is known by many names. In the shops it is often called 'baby's tears' or 'pearl weed'. Botanically it used to be called Hemianthus micranthemoides "HM" and Micranthemum micranthemoides "MM" but in recent years it has been discovered that it is neither. Its real name is Hemianthus glomeratus. However, apart from a handful of botanists and enthusiasts, it seems rare to find anyone using the correct name. Most commercial brands still use 'Hemianthus micranthemoides' on their labels.

Hemianthus glomeratus is a green stem plant with thin green leaves and thin green stems. The leaves of H. glomeratus are opposite (with 2 leaves per stem node), but it often grows in whorls of 3 to 4 leaves. Its small size and ease of growth make it a top choice for aquascapers as it can be placed anywhere in an aquascape. It can be a dense background shrub or a small foreground plant, depending on how short you cut it. 

Pearlweed is used on both the left and right of this scape to fill in the middle ground.

It is an extremely hardy plant and will grow well in tanks without CO2 injection, making it an excellent choice for non CO2 tanks. If there are nutrients in the water column, the plant can be grown without substrate. It is not fussy about water parameters. In tanks with more light the internodes are shorter and the plant branches more. It will also creep along the carpet in high light and open areas.

Its ability to be trimmed at any height makes it a very flexible plant to place in the aquarium. It can be pruned to a short bush just a few inches high or used as a taller background plant.

Pearl weed as a taller midground bush in this tank.

Key success factors

• Medium to high light produces more compact plants
• Comprehensive water column nutrient availability necessary for long term health

Trimming & Propagation

Cut above an internode and plant the top section in the substrate. New growth heads will sprout from the base of the plant. Over many cutting cycles, older stems will begin to deteriorate and need to be discarded and replaced with fresh new tops.

Pearl weed bush (right side) in a low tech planted tank.