Pearlweed
Hemianthus glomeratus
Synonyms Hemianthus micranthemoides · Micranthemum micranthemoides · Baby tears · Pearl weed · Pearl grass · Micranthemum glomeratum
Pearlweed (Hemianthus glomeratus) is a stem plant for the foreground and the midground, growing to about 20 cm (7.9 in) at a fast pace. It wants 64–82°F (18–28°C), medium light and CO₂ if you have it, and counts as an easy plant to keep alive.
At a glance
| Type | Stem plant |
|---|---|
| Light | MediumThe least light it survives in, not the light it looks best in. |
| CO₂ | RecommendedWhether it survives without added CO₂ — not whether CO₂ would help it grow faster. |
| Difficulty | Easy |
| Temperature | 64–82°F (18–28°C) |
| Max height | 20 cm (7.9 in)Grown submersed, left to mature, never trimmed. |
| Growth rate | Fast |
| Placement | planted in the foreground and the midground |
| pH | 6–7.5 |
Before it goes in
- Pearlweed needs medium light. Under a low-light LED it thins out instead of filling in.
- CO₂ is not required, but without it expect slow growth and a thinner result.
- In too little light it stretches: long bare stems between leaves instead of a bushy plant.
- At about 20 cm (7.9 in) it belongs behind everything shorter — planted at the front it hides the rest of the scape and shades it.
- Its leaves are soft: Goldfish, Common Pleco and Molly will eat it.
Can it grow without CO₂?
Yes, but slowly. Pearlweed is listed as CO₂-recommended, not CO₂-required: without injection it survives and grows, it just takes far longer to fill in.
How much light does it need?
Medium light — and that is the survival line, not the “it looks better” line. Below it, this one stretches instead of spreading.
How big does it get?
About 20 cm (7.9 in) tall when it is mature and untrimmed, growing fast, after roughly 2 weeks to root in.
Will my fish eat it?
Its leaves are soft, so some will: Goldfish, Common Pleco and Molly.
What it goes with
- Plants that run on the same light and CO₂, so they can share a tank without one of them being the odd one out: Water Sprite, Anubias nana 'Petite', Cryptocoryne wendtii and Dwarf Hairgrass Mini.
- Animals that share its temperature range and will not eat or uproot it: Betta, Cherry Shrimp, Angelfish and Bristlenose Pleco.
Often compared with
| Pearlweed | Hygrophila lancea 'Araguaia' | Blyxa japonica | |
|---|---|---|---|
| Light | Medium | Medium | Medium |
| CO₂ | Recommended | Recommended | Recommended |
| Max height | 20 cm | 20 cm | 15 cm |
| Difficulty | Easy | Medium | Medium |
More plants
Sources (3) · checked Sep 2026
- Growth in low light, CO₂, Shapeaquasabi.com
- Shapeaquariumplantsfactory.com
- Max heighttropica.com