I dumped iron supplements into my 20-gallon for three months straight. The Ludwigia Repens Super Red Mini stayed stubbornly green.
That was back in early 2023, and I was convinced I’d bought a mislabeled plant. Turns out, I was chasing the wrong variable entirely.
Ludwigia Repens Super Red Mini develops deep red coloration primarily from high light intensity (50+ PAR at the plant), not iron supplementation. Iron matters, but it’s maybe 15% of the equation. Light does the heavy lifting, around 60%, with nutrient balance (specifically limiting nitrates while maintaining phosphate) handling the rest.
I’ve grown this cultivar in four completely different tank configurations since March 2024. High-tech with CO2, low-tech without it, lean dosing, heavy dosing. The results genuinely surprised me, and they contradicted about half of what I’d read in aquarium forums.
Here’s everything I learned, the test data, the parameters that actually matter, and the mistakes that kept my plants looking washed out for way too long.
What Exactly Is Ludwigia Repens Super Red Mini?
Ludwigia Repens Super Red Mini is a compact cultivar of the North American native Ludwigia repens (Linnaeus, 1753), selectively bred for smaller leaf size and intensified red pigmentation. Leaves reach 0.5-1 inch versus 1-2 inches on standard varieties. Maximum height typically stays under 12 inches in aquarium conditions.
This plant belongs to the Onagraceae family, same family as evening primroses, weirdly enough. The “mini” designation refers specifically to leaf dimensions, not overall plant height. I’ve seen specimens hit 16 inches in high-tech setups, which always catches people off guard.
The leaves emerge in opposite pairs along square-ish stems. New growth comes in green or bronze at the top, then transitions to red as it matures and receives adequate light. That transition zone? That’s actually your diagnostic tool for whether conditions are right.
Where this gets confusing: Several nurseries sell similar-looking plants under slightly different names, Ludwigia sp. ‘Mini Super Red,’ Ludwigia palustris ‘Super Red,’ and generic “mini red ludwigia.” They’re probably the same thing, but tissue culture sources may have subtle genetic differences. I’ve bought from three suppliers and noticed minor leaf shape variation between them.
[IMAGE #1 PLACEMENT: Ludwigia Super Red Mini Identification Guide]
For context on how this compares to other red stem plants, the color intensity rivals what you’d get from Rotala rotundifolia varieties, but the growth habit is more compact and less demanding overall.
The Iron Myth: Why Dumping Flourish Iron Doesn’t Turn Plants Red
MYTH: “Iron deficiency causes green coloration in red plants. Dose more iron for deeper red.”
REALITY: Iron deficiency causes yellowing of new growth, not loss of red color. Red pigmentation (anthocyanins) develops primarily as a photoprotective response to high light intensity. Plants produce these pigments to shield chlorophyll from light damage, it’s basically botanical sunscreen.
Iron is necessary for healthy growth and chlorophyll production. Iron-deficient plants look pale and sickly, which people interpret as “not red enough.” So they add iron, the plant gets healthier, and sometimes coincidentally gets more light exposure or grows into higher-light zones, then they credit the iron for the color change.
Maintain adequate iron (0.1-0.5 ppm) but focus your energy on lighting. I wasted probably $60 on Seachem Flourish Iron before I figured this out.
There’s a second myth I believed for years: that CO2 injection is mandatory for red coloration. Not true. CO2 accelerates growth and can indirectly help by letting plants grow into high-light zones faster, but I’ve achieved deep red color without it.
More on that in my test results below.
Light Requirements: The 50 PAR Threshold
This is where most people’s Ludwigia Super Red Mini stays green forever.
I measured PAR levels in my tanks using an Apogee MQ-500 meter (borrowed from a reef keeper friend, those things cost $500+ so I wasn’t buying one). The results were eye-opening.
Ludwigia Repens Super Red Mini requires 50+ PAR at the plant tops for red coloration to develop. Below 40 PAR, plants remain predominantly green with bronze undertones. Above 80 PAR, you’ll see the deepest crimson, but algae management becomes critical. Photoperiod should be 7-9 hours daily.
What this means practically: Most budget LED lights marketed as “planted tank lights” deliver 30-50 PAR at 12 inches depth. That’s borderline for this species. The Ludwigia might survive, it’ll grow, look healthy-ish, but it won’t turn red.
I learned this the hard way with a Nicrew ClassicLED Plus on my first 20-gallon. Plants grew fine. Stayed green. I blamed everything except the light because the package said “for planted tanks.” Upgrading to a Fluval Plant 3.0 and cranking intensity to 80% finally got the color I wanted.
For a deeper dive into LED lighting and PAR values, that guide covers the measurement process.
My 4-Tank Experiment: What Actually Produces Red Color
Alright, here’s the data I wish someone had shown me two years ago.
From March through September 2024, I grew Ludwigia Repens Super Red Mini in four different setups simultaneously. Same source plants (tissue culture from Tropica, divided into four portions). Different conditions.
| Tank | Light (PAR) | CO2 | Nitrate | Result |
| 20G High-Tech | 85 PAR | Yes (30ppm) | 10-20 ppm | Deep crimson, fastest growth |
| 20G No-CO2 | 75 PAR | No | 5-10 ppm | Strong red, slower growth |
| 10G Medium Light | 45 PAR | Yes (25ppm) | 15-25 ppm | Bronze-green, minimal red |
| 10G Low Light | 25 PAR | No | 10-15 ppm | Green, leggy growth |
SETUP DETAILS:
- Duration: 26 weeks
- Substrate: All used ADA Aquasoil
- Fertilization: Tanks 1&3 used EI dosing, Tanks 2&4 used lean dosing with root tabs
- Water Changes: 50% weekly for all tanks
Tank 2 (no CO2, high light, lean dosing) produced color nearly as deep as Tank 1. The growth rate was maybe 40% slower, but the red was almost indistinguishable. This completely changed how I think about “high-tech requirements.”
Light intensity is non-negotiable for color. CO2 is negotiable, it speeds things up but isn’t mandatory. Lean nitrate levels (under 15 ppm) may actually enhance red coloration by triggering stress-response pigment production.
Sample size of 4 tanks, single plant source. Results might vary with different cultivar sources or water chemistry.
The Tank 2 result is what really got me. I’d been telling people for years that CO2 was “necessary” for red stem plants. I was wrong, or at least, I was oversimplifying.
What CO2 actually does is enable faster growth, which lets plants reach high-light zones quicker and sustain that growth rate. But if you’re patient and your light is strong enough, you can absolutely get there without pressurized CO2. The liquid carbon alternatives work as a middle-ground option too.
Water Parameters: The Full Specification Sheet
SCIENTIFIC: Ludwigia repens ‘Super Red Mini’ (cultivar)
COMMON NAMES: Mini Super Red Ludwigia, Ludwigia Super Red Mini, Super Red Mini Ludwigia
FAMILY: Onagraceae
PARAMETERS (Research-Based + Tested):
- Temperature: 68-82°F (20-28°C) | Optimal: 72-78°F (22-26°C)
- pH: 6.0-7.5 | Optimal: 6.5-7.0
- Hardness: 3-15 dGH (50-250 ppm)
- CO2: Not required, beneficial for growth rate
- Light: Medium-High (50-100+ PAR at plant)
- Nitrate: <20 ppm for color, <40 ppm acceptable
REAL-WORLD CONTEXT:
“I’ve kept this species at pH 7.4 with 12 dGH, harder than ‘optimal’, without issues. Color developed normally under high light. Don’t stress if your parameters aren’t textbook perfect.”
GROWTH DATA:
- Rate: 0.5-2 inches/week depending on conditions
- Height: 6-16 inches typical
- Width: 2-4 inches spread
- Propagation: Stem cuttings (replant tops and stems)
CARE REALITY CHECK:
- Difficulty: Easy to grow, Moderate to color up
- Beginner-Suitable: Yes, if lighting meets minimum
- Common Failure: Inadequate light blamed on other factors
COSTS (2025):
- Initial: $6-12 per tissue culture cup, $4-8 per stem bunch
- Monthly: ~$3 (portion of fertilizer costs)
- Setup: Adequate lighting may require $50-150 upgrade
One parameter I want to highlight: nitrate levels. Research on terrestrial plants (and some aquatic species) suggests that limiting nitrogen can push plants toward anthocyanin production as a stress response. I noticed slightly deeper reds in my lean-dosed tank compared to the EI-dosed tank at similar light levels.
This doesn’t mean starving your plants. It means maybe targeting 5-15 ppm nitrate rather than the 20-40 ppm range that EI dosing method produces. Trade-off: slower growth.
Planting, Propagation, and Placement
Getting Ludwigia Super Red Mini established is straightforward, but there are a few tricks.
Initial planting:
- Remove any rock wool or gel medium completely, this stuff rots underwater
- Separate individual stems (tissue culture cups usually contain 10-15 stems)
- Trim any brown or mushy roots, leaving 1-2 inches of stem below the lowest node
- Plant stems 1-2 inches deep, spaced 1 inch apart for bushy growth
- Expect some melt during the first 2 weeks, this is normal for tissue culture
The melt thing still catches people off guard. I had someone message me convinced their plants were dying when really the emersed-grown leaves were just transitioning to submersed growth. New underwater leaves replace them within 2-3 weeks.
Propagation is stupid easy. When stems reach 6+ inches, cut the top 3-4 inches and replant. The original stem sprouts side shoots, the cutting develops roots within a week. I’ve turned a single tissue culture cup into 40+ stems over four months using this method.
For placement, put this plant in mid-ground to background positions where it can receive direct light without being shaded by taller plants. I learned to avoid placing it behind my java fern varieties, the shadow killed the red coloration on lower leaves.
Troubleshooting: When Things Go Wrong
Problem: Green or bronze coloration, no red
This is lighting 90% of the time. Before you change anything else:
- Measure or estimate PAR at plant height
- Increase intensity or reduce distance to light
- Extend photoperiod to 8-9 hours (but watch for algae)
If lighting is confirmed adequate (50+ PAR), check nitrate levels. Try limiting to 10-15 ppm for 3-4 weeks.
Problem: Yellowing new growth
This actually is iron deficiency, or possibly a general micronutrient shortage. Increase iron supplementation or add a comprehensive micro fertilizer. I use Seachem Flourish as my baseline, with added Flourish Iron for heavy red-plant tanks.
For a full diagnostic approach to nutrient deficiencies, that guide covers all the symptoms.
Problem: Leggy growth with large gaps between leaves
Low light or insufficient nutrients. The plant is stretching toward light sources. Either increase lighting or prune aggressively and replant tops in better positions.
Problem: Algae on leaves
Too much light, too little CO2, or nutrient imbalance. This is the trade-off with high-light setups, you’re walking a line between red coloration and algae paradise. Make sure your nutrients are balanced and consider adding CO2 supplementation if algae becomes persistent.
Complementary Plant Pairings and Tank Mates
The deep red of Ludwigia Super Red Mini creates stunning contrast against green carpeting plants. I’ve had great visual results combining it with Monte Carlo in the foreground and Anubias Nana Petite attached to hardscape elements.
For fish compatibility, pretty much anything that doesn’t eat plants works. Cherry shrimp are particularly striking against the red leaves, the color pop is ridiculous. Small schooling fish like ember tetras complement without competing visually.
Avoid pairing with aggressive plant-eaters like silver dollars or large cichlids. Common plecos can also damage stems while grazing for algae, smaller species like otocinclus are safer choices.
Final Thoughts: What I’d Tell Myself Two Years Ago
If I could go back to 2023 when I was frustratedly dosing iron into that green Ludwigia, I’d say this:
Stop chasing nutrients. Upgrade your light.
That single change would have saved me months of troubleshooting and probably $80 in supplements I didn’t need. Ludwigia Repens Super Red Mini isn’t a difficult plant, it just has one non-negotiable requirement that most “beginner planted tank” setups don’t meet by default.
Get above 50 PAR at the plant. Keep nitrates moderate. Be patient during the transition period when tissue culture is adapting. The red will come.
And if you’re wondering whether you need CO2, you don’t. I’m running that Tank 2 setup from my experiment as my main display tank now. Beautiful red Ludwigia. Zero gas injection. Just patience and a decent light.