Red Star Ludwigia

About

Ludwigia glandulosa is the one Ludwigia in this catalogue you can name without touching it: its leaves come off the stem one at a time, alternating up the shoot, while Ludwigia repens, Ludwigia palustris and Ludwigia arcuata all set theirs in opposite pairs, two to a node. A happy plant is a stiff, unbranched column - narrow lanceolate leaves 3 to 11 cm long on a stem over 3 mm thick, wine red to red-violet on both faces, climbing dead straight for the surface like a young fir. It hardly ever branches on its own, which is why it is a fixture of Dutch-style 'streets' and why the only way to make it bush is to cut the leading tip; the stump below the cut is what finally throws side shoots. It comes from the southeastern USA, north as far as Illinois and Indiana, and has been in the hobby since the late 1980s - the one dealer listing that files it under Central America is simply wrong. The colour is conditional, and the first condition is light. Flowgrow calls it a Starklichtpflanze, a strong-light plant, and the documented failure mode matches: too little light and the leaves first go olive green with a wine-red underside, then drop. Even under plenty of light it sheds its lowest leaves as a matter of habit, so plan something shorter in front of the bare stem base. Ignore the low-nitrate folklore that follows red plants around, though - unlike most red stems this one does not need starved nitrate to stay red, and Flowgrow's working range is 10 to 50 mg/l NO3 (the culture notes say it grows well at 5 to 25). Flowgrow is equally explicit that it makes no great macro demand: what actually drives the pigment is strong light plus an unbroken iron and micronutrient supply, and if those lapse the red-violet drains back to green no matter what the NPK numbers say. CO2 is not optional either: without it growth slows to a crawl and the colour never really arrives. Two failure modes appear on no label. The first is the changeover: nursery pots and tissue cups are grown emersed, those emersed leaves are shed once the stem is under water, and because this is the slowest Ludwigia we list the submersed replacement growth is weeks away rather than days - a freshly planted group looks like it is dying before it looks like anything, and the mistake is to pull it or to panic-dose. The second is the ceiling: Flowgrow states plainly that the stem grows straight to the water surface and then breaks through it without branching. Aquasabi's recommended tank height is 15 to 60 cm, so in anything shallow the tip converts to emersed growth and the submersed length below it goes bare. Top it on a schedule, not when it looks tall. Sources split on several numbers, and this record takes the harder reading each time. Flowgrow and Aquasabi demand high light where Tropica rates it medium; Flowgrow wants 20 to 40 mg/l CO2 where Tropica rates the demand only medium; Flowgrow caps pH at 7 where Dennerle prints 5 to 8. Even the difficulty is contested inside a single source - Flowgrow's table says 'mittel' while its own culture text opens by calling it a rather demanding plant, and EpicAquatics rates it outright difficult. Water chemistry is the real trap: this plant wants acidic, carbonate-poor water, and keepers in hard water report it only manages with injected CO2 and advanced iron chelates. General hardness it tolerates broadly - Flowgrow publishes no dGH at all, Aquasabi's 0-30 is a tolerance rather than a target and Dennerle prints 0-20 - but carbonate hardness above roughly 10 dKH is the ceiling that actually stops it. Held permanently above 25 C, colour and vigour both fade. Every nursery table calls the growth rate medium, yet Tropica's own description and most care guides say slow growing; slow is the practical truth, and this is the slowest Ludwigia we list. That combination - mandatory high light, mandatory CO2, soft carbonate-poor water and a slow recovery from any mistake - is why we rate it a step harder than the 'medium' the shops print, and harder than our other three Ludwigias. In the shop it is usually mislabelled. 'Ludwigia peruensis' is a fantasy name invented from perennis and belongs to no species at all; 'Ludwigia perennis' and 'Ludwigia peruviana' are real but different plants that are not in the hobby, which is why neither is carried here as a synonym, and Tropica admits it sold this one as perennis for years. The trap also runs backwards: the label L. glandulosa, or the misspelling 'glandiosa', is sometimes stuck on Ludwigia 'Rubin', a red form of L. repens. Count the leaves at a node - Rubin has two, branches freely and grows fast; glandulosa has one, refuses to branch and takes its time.

Care

Treat it as a high-light plant with injected CO2 at 20 to 40 mg/l and unbroken iron and trace dosing - that combination, not nitrate starvation, is what makes it wine red on both leaf faces, and NO3 can sit anywhere in the normal 10 to 50 mg/l range. Give it soft, carbonate-poor water: pH 5 to 7 and KH 2 to 10 dKH, with hard tap water needing an RO cut or, at minimum, CO2 plus a strong chelated iron. Plant five to seven stems two to three centimetres apart in a nutrient-rich substrate; because a stem grows straight up without side shoots, a group is built by planting one, not by waiting for one to spread. Expect a new group to drop its emersed nursery leaves first and to look worse before it looks better - give it weeks, and do not pull it or re-dose in panic. Expect the lowest leaves to keep dropping even when everything is right, so keep a shorter plant in front. Trim by cutting the head and replanting it - the cut is also what forces the stump to branch - and do it on a schedule, because an untopped stem breaks through the surface and leaves the submersed length bare. Growth is slow, and the tank is best kept under 25 C for colour.

Diet

Feeds from both the substrate and the water column: root the stems in a nutrient-rich soil and dose a full macro plus micro programme. Iron is the pigment lever here - Flowgrow's bands are 0.01 to 0.5 mg/l Fe alongside 0.1 to 3 mg/l PO4 and 5 to 30 mg/l K, and it says outright that no unusually high nitrate or phosphate is needed - so it is a lapse in traces, not a surplus of nitrate, that turns the leaves green.

Frequently asked questions

What water parameters does a Red Star Ludwigia need?

Red Star Ludwigia does best at 10–27 °C (50–80.6 °F), pH 5–7 and a general hardness of 1–20 °dGH.

Where should Red Star Ludwigia be placed in the aquarium?

Red Star Ludwigia works best in the midground and reaches around 40 cm.

Is the Red Star Ludwigia suitable for beginners?

Red Star Ludwigia is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.

Sources

• Ludwigia glandulosa (Rote Sternludwigie) - Flowgrow Wasserpflanzen-Datenbank (PRIMARY)
• Ludwigia glandulosa | Aquasabi - Aquascaping Shop
• Ludwigia glandulosa (035A) - Tropica Aquarium Plants
• Dennerle Ludwigia glandulosa in Pot - East Ocean Aquatic
• Ludwigia peruensis? - UKAPS forum thread 70342
• Ludwigia glandulosa - EpicAquatics
• Ludwigia Glandulosa Care Guide - Melbourne Tropical