Pearlweed
Hemianthus micranthemoides
easy careOverview
Pearlweed (Hemianthus micranthemoides) is one of the most versatile easy plants in the hobby. A relative of the demanding HC Cuba, it is far more forgiving: fine, bright green leaves on delicate stems that will either creep into a low carpet or grow up into a soft bush, depending entirely on how you plant and trim it. Fast-growing and undemanding, it is a superb nutrient sponge for a young tank and a great choice for anyone who wants a foreground effect without committing to full high-tech gear.
Planting & placement
Pearlweed is happiest in the foreground or midground. It comes as loose stems or tissue-culture portions; separate them and plant small groups into the substrate with tweezers. For a carpet, plant many short stems close together and keep trimming them low so they branch sideways; for a bush, plant fewer and let them rise. Because it roots readily, a nutrient substrate helps but is not essential — the how to plant aquarium plants guide covers the technique, and it looks great massed in front of taller stems in a beginner aquascape.
Light, CO2 & ferts
Give pearlweed medium to high light to keep it compact — this is the single biggest factor in how it grows. In dim tanks it stretches toward the surface and goes pale and leggy. CO2 is beneficial but optional; it thickens the plant and helps a carpet stay flat. As a fast grower it is hungry, so dose a complete water-column fertilizer regularly — our best fertilizer picks keep it green.
Propagation & problems
Propagation could not be simpler: snip a healthy top, replant it, and it roots into a new plant. A single portion multiplies into a thick stand within weeks. The main problems are legginess from low light and the fine leaves catching debris or algae if flow is poor or the tank is unstable — see how to get rid of aquarium algae. Keep the light adequate, the water clean and the plant well fed, and pearlweed is one of the most rewarding, flexible easy plants you can grow.
Pearlweed — frequently asked questions
Can pearlweed be used as a carpet?
Yes. Under good light, planted densely and trimmed low, pearlweed creeps horizontally and forms a bright green carpet. Left alone it grows upward as a bushy stem, so it works as a foreground carpet or a midground filler depending on how you trim it.
Does pearlweed need CO2?
No, it grows without injected CO2 under medium light, which makes it far easier than a true carpet like HC Cuba. CO2 makes it denser and faster and helps it stay low and compact, but it is not required.
Why is my pearlweed growing leggy and pale?
Leggy, pale, stretched growth almost always means not enough light. Pearlweed reaches for the surface in dim tanks. Raise the light or move it higher in the tank, and add fertiliser so it has the nutrients to grow densely.
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