Ludwigia repens (creeping primrose-willow) care

Light

Bright but filtered. Ludwigia repens burns within days in unfiltered south-facing summer sun, and stops growing within months in deep shade. Submerged plant that grows green-and-olive in moderate aquarium light and turns vivid red under high LED output (roughly 40-70+ PAR). More light means redder, more compact growth. If you only have a south window, set the plant back 1.5 m or hang a sheer curtain — both knock the intensity down into the right range.

Watering

Watering ludwigia repens: submerged permanently; 30-50% aquarium water changes weekly. The number that matters isn't the day of the week — it's how dry the top 2-3 cm of the pot feels. A finger in the soil tells you more than a watering app. After every watering, tip the saucer. Lives underwater in freshwater. Adaptable across soft to hard water (3-15 dGH), pH 6.0-8.0. Grows without CO2 but is denser and far redder with injection (15-30 ppm).

Soil and pot

Ludwigia repens grows best in aquarium gravel or aquasoil substrate. Roots readily in gravel, sand or nutrient aquasoil. A heavier root feeder than the rotalas, it benefits from root tabs in inert substrates. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Ludwigia repens sits happiest at around 100% (submerged aquatic) humidity and 18-28°C (64-82°F). Grown fully underwater, so ambient humidity does not apply. It also grows emersed in humid bog and pond-margin settings, where it produces small yellow flowers above the water. If you keep the room above 18 year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed ludwigia repens sparingly. Dose a balanced liquid aquarium fertiliser (nitrate, phosphate, potassium, trace) plus root tabs in inert substrates; iron strongly supports red coloration. Note copper-based fertilisers and dosing can harm shrimp sharing the tank. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on ludwigia repens in the Growli community. Each is annotated with the most common cause so you know where to start.

• Stays green instead of red — Red colour is driven by high light, lean nitrate and good iron. Increase PAR and iron dosing; under modest light it grows healthy but olive-green.
• Lower-leaf drop — Shading from a dense canopy or low nutrients strips lower leaves. Thin the top, raise light, and add root tabs in inert substrate.
• Melting on emersed-to-submerged transition — Nursery-grown emersed stems often shed leaves underwater. Keep parameters stable; new submerged growth follows within a couple of weeks.
• Copper sensitivity for tankmate shrimp — Not a plant problem but a tank one: copper-bearing fertilisers used to colour Ludwigia can harm shrimp. Use shrimp-safe dosing if keeping invertebrates.

Propagation

Cut the top 8-12 cm of a stem and replant the cutting, which roots quickly; the parent stem branches at the cut and side shoots can also be separated. Standard cut-and-replant stem propagation. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Ludwigia repens is mildly toxic to pets. Ludwigia is not listed by the ASPCA on either the toxic or non-toxic plant lists (it does not appear on the ASPCA 'L' list), so its pet status is unconfirmed. Treat with caution and verify with a vet; as a submerged aquarium plant, ingestion by cats or dogs is unlikely in practice. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Ludwigia repens deep-dive guides

Every aspect of ludwigia repens care, each with its own calibrated guide:

• Ludwigia repens watering schedule
• Ludwigia repens light requirements
• Best soil mix for ludwigia repens
• Ludwigia repens fertilizing guide
• When to repot ludwigia repens
• How to propagate ludwigia repens
• Ludwigia repens growth rate & size
• Ludwigia repens cold hardiness
• Ludwigia repens temperature & humidity
• Is ludwigia repens toxic to cats & dogs?
• Is ludwigia repens toxic to cats?
• Is ludwigia repens toxic to dogs?

Featured in these plant shortlists

Ludwigia repens qualifies for 1 curated Growli shortlist — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best plants for a north-facing window — Houseplants for a north-facing window: bright, even, indirect light and no scorching direct sun. Each pick verified against its documented light needs.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Ludwigia repens is also commonly called creeping primrose-willow or red Ludwigia.

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