The short answer
A dense carpet is a high-light, high-demand project for most species: bright light, injected CO2, a nutrient-rich substrate and regular dosing. Get any of those wrong and the plant grows tall and patchy instead of spreading. If you want a carpet without CO2, choose an easy species like dwarf sagittaria and accept a looser, taller look.
The full recipe
To carpet the demanding classics — dwarf baby tears (HC), Monte Carlo and dwarf hairgrass — you need all four in balance:
- Light: strong, even coverage. See the best planted-tank lights.
- CO2: pressurised injection is what keeps carpets low and green — CO2 for beginners and the CO2 hub.
- Substrate: an active aqua soil feeds the roots — substrate picks and the substrate hub.
- Fertiliser: an all-in-one tops up the water column.
Plant it right
Split the pot into small clumps and plant each one a few centimetres apart across the substrate — they’ll fill the gaps as they spread by runners. Planting tight from the start just wastes plants. Our planting guide shows the technique, and aquascaping for beginners covers the layout.
Be patient
Carpets fill in over weeks, not days, and the gaps are where algae likes to settle early on. Keep water changes up, don’t over-run the lights, and let the plants win. Once established, a quick trim keeps the carpet dense and encourages it to spread sideways rather than up.