Purple Bacopa (Salzmann's Bacopa) care

Light

Bright but filtered. Purple Bacopa burns within days in unfiltered south-facing summer sun, and stops growing within months in deep shade. Demands high aquarium lighting (PAR 50-100+) to develop its characteristic purple pigmentation. Under low light, the undersides remain green and growth slows considerably. A 10-12-hour photoperiod with quality full-spectrum LEDs is ideal. 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 purple bacopa: fully submerged aquatic plant; maintain in aquarium water continuously. 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. Prefers soft, slightly acidic to neutral water, pH 6.0-7.2, temperature 22-28°C. CO2 injection at 20-30 ppm significantly enhances growth rate and colour intensity. Weekly water changes of 30% keep nutrient levels optimal.

Soil and pot

Purple Bacopa grows best in nutrient-rich fine aquatic substrate. Plant in a quality planted-tank substrate (e.g., ADA Aqua Soil or Fluval Stratum) to supply root nutrition. Stems can also grow in plain gravel with root tabs, though growth is slower. Plant in groups of 5-7 stems for best visual impact. 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

Purple Bacopa sits happiest at around 100% (fully aquatic) humidity and 22-28°C (72-82°F). Fully submersed aquatic. Can be grown emersed in paludarium or riparian setups with roots in moist substrate and ambient humidity above 75%; emersed leaves are typically green. If you keep the room above 22 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 purple bacopa sparingly. Apply a comprehensive liquid aquarium fertiliser weekly, ensuring adequate potassium and micronutrients. Iron supplementation (0.1-0.2 ppm) deepens purple pigmentation. Avoid over-fertilising with nitrogen, which shifts colour toward green. 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 purple bacopa in the Growli community. Each is annotated with the most common cause so you know where to start.

• Green instead of purple coloration — Caused by low light or excess nitrogen; increase lighting intensity and reduce nitrate levels below 10 ppm.
• Leaf drop on lower stems — Normal as plant ages; trim tops and replant them while discarding the bare lower sections.
• Very slow growth — Without CO2 injection this plant grows very slowly; adding CO2 at 20-30 ppm dramatically accelerates growth.
• Algae coating — Reduce photoperiod, add fast-growing foreground plants to outcompete algae, and ensure adequate water circulation.
• Melting after introduction — Transition melt is common; remove dead leaves, maintain stable parameters, and new growth emerges within 2-3 weeks.

Companion plants

Purple Bacopa pairs well with Ludwigia repens, Rotala macrandra, and Hemianthus micranthemoides. These are species with similar light and water needs, so you can group them in the same room or on the same shelf and water as a batch.

Propagation

Take stem cuttings 6-10 cm long from healthy growing tips, remove the lower 2-3 pairs of leaves, and anchor in substrate. Roots develop in 1-2 weeks under good light. Regular trimming and replanting of tops keeps the plant bushy and vigorous. 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

Purple Bacopa is pet-safe. Bacopa salzmannii is not individually listed by the ASPCA. The broader genus Bacopa (including B. monnieri) has no documented mammalian toxicity and is widely considered safe in aquatic environments with fish and invertebrates. 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.

Purple Bacopa deep-dive guides

Every aspect of purple bacopa care, each with its own calibrated guide:

• Common purple bacopa problems & fixes
• Purple Bacopa watering schedule
• Purple Bacopa light requirements
• Best soil mix for purple bacopa
• Purple Bacopa fertilizing guide
• When to repot purple bacopa
• How to propagate purple bacopa
• How to prune purple bacopa
• What's eating my purple bacopa?
• Purple Bacopa growth rate & size
• Purple Bacopa cold hardiness
• Purple Bacopa temperature & humidity
• Is purple bacopa toxic to cats & dogs?
• Is purple bacopa toxic to cats?
• Is purple bacopa toxic to dogs?

Featured in these plant shortlists

Purple Bacopa qualifies for 7 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best pet-safe houseplants — Houseplants the ASPCA lists as non-toxic to cats and dogs — every one verified against the ASPCA toxic and non-toxic plant list.
• 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.
• Best pet-safe plants for bright light — Non-toxic to cats and dogs and happy in a bright, sunny spot — safe plants for your best-lit windowsill.
• Best small & tabletop houseplants — Compact houseplants that stay under about 40 cm — desk, shelf and windowsill plants that never outgrow a small space.
• Best cat-safe plants — Houseplants the ASPCA lists as non-toxic to cats (and dogs) — safe greenery for a home with a curious cat.
• Best dog-safe plants — Houseplants the ASPCA lists as non-toxic to dogs (and cats) — safe greenery for a home with a curious dog.
• Best small pet-safe plants — Compact, tabletop houseplants that are also ASPCA non-toxic to cats and dogs — safe greenery for a desk or shelf.
• Browse all 30 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Purple Bacopa is also commonly called Purple Bacopa or Salzmann's Bacopa.

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