As a carpeting foreground plant, one can hardly fault Hydrocotyle tripartita ‘Japan’. This Southeast Asian import grows fast, low, and carpets densely in a uniform manner. The small leaf form makes it especially useful in a nano-tank, but equally at home in a larger tank where it will quickly spread across the substrate to form a lush, verdant carpet. It occupies the same genus as Brazilian Pennywort (Hydrocotyle leucocephala) but is more versatile because of its predictable growth habit. While dosing is not required, the growth of H. tripartita will be noticeably faster with CO2 diffused into the water column.
While some sources recommend the physical compression of the plant to encourage carpeting, this author finds that pressing is not necessary, especially if a mat is placed in the tank where H. tripartita will naturally creep across the substrate without any help. When new growth pushes up against the sides of the tank and forces the plant to grow upwards, simply prune H. tripartita as necessary. As with most fast-growing plants, keep H. tripartita happy by fertilizing the water-column or placing root-tabs in the substrate. For best results, avoid shading and grow H. tripartita with a medium-high light.