This month’s plant of the month is Ludwigia (Ludwigia Repens).
This plant is native to streams, bogs, and lakes in tropical and sub tropical fresh waters of Central and North America. Although sold in the aquarium trade as a purely aquatic plant, it is really a bog plant and will grow just as well only partially submerged.
The leaves are spade shaped and shoot off from the central stalk of the plant. The colors of the leaves vary depending on the amount of light available and the nutrients available. Typically, the tops of the leaves are a bright green and the underside range from a burgundy to rusty or pale green. With higher light underside will be more in the bright burgundy range.
In the aquarium, Ludwigia makes a great mid ground plant or even a background plant if planted in clumps. The colors make a great break from just green leafy plants. If growing as a background plant, removing the bottom few leaves will promote new stalk outshoots from where the leaves were to “fill in” an area better. In higher light tanks, regular pruning may be needed, as it has a tendency to grow quickly.
Substrate, while this plant does best in fertilized sand, or top soil, I’ve had great success with this plant in gravel as long as I use root fertilizer (aquarium root tabs) regularly (no more than once a month). Fertilizing with trace elements including iron and dosing with CO2 will improve the coloring and growth of Ludwigia in moderately to high light tanks. As for pH, in general, Ludwigia prefer neutral or near neutral. As this plant ranges from tropical to sub tropical, it will do well in all but cold water setups. This makes it ideal for tropical or native species tanks.
Propagation is very easy. When pruning, trim off the top, if there are root offshoots from the stalk, trim just under the roots and replant. At the place where the trimming occurred, two or more new stalks will come off from that site. Or, after the plant has reached the surface, yellow flowers will appear (assuming enough broad spectrum light is available) seeds will form and drop onto the substrate.
Ludwigia Repens makes a great addition to most tanks. However, tanks with low lighting or that do not have full spectrum (5000-7000K range), will not be good homes for this colorful plant. And, if CO2 levels are lower, they will grow fairly slow.
(Sources, USGS, Drs Foster and Smith, USFWS, Personal experience)
