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Plant care

Blue Star Water Lily (Star Lotus) care

Nymphaea stellata

Also called Blue Star Water Lily, Star Lotus, Blue Lotus.

RHS H1bUSDA 9-12Mildly toxic to petsIndoor Leaf spread 60-100 cm

Watering rhythm

Direct sun (at least 4-6 hours)

Fully aquatic; roots and tuber submerged, leaves and flowers floating or emergent

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Light

Direct sun (at least 4-6 hours)

Soil

Heavy aquatic compost in pond basket

Humidity

Aquatic; open pond conditions

Temp

24-32°C

Pet safety

Mildly toxic to pets

Mature size

Leaf spread 60-100 cm

Care at a glance

Light

Blue Star Water Lily needs sun on the leaves, not just bright ambient room light. Requires full sun — a minimum of 5-6 hours of direct sunlight daily for reliable flowering. In partial shade, plants grow but rarely bloom. Ideal for open ponds, water features, or large tubs in sunny gardens. A south or west-facing windowsill in the northern hemisphere is the default; anywhere else, expect the plant to stretch and pale out within a season.

Watering

Water blue star water lily fully aquatic; roots and tuber submerged, leaves and flowers floating or emergent. The actual day count varies with pot size, light, and season — the finger test (or lifting the pot to feel its weight) is more reliable than a fixed calendar. Empty any drainage saucer afterwards so the pot isn't sitting in water. Thrives in still or gently moving freshwater, pH 6.5-8.0, temperature 24-32°C. Plant in ponds at a depth of 30-60 cm over the tuber crown. Tolerates warm water better than many water lilies and blooms profusely in tropical summers.

Soil and pot

Blue Star Water Lily grows best in heavy aquatic compost in pond basket. Use a planting basket filled with heavy aquatic compost or a loam-based mix. Top with washed gravel to prevent compost escape. Fertilise the basket at planting and again mid-season with aquatic fertiliser pellets. 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

Blue Star Water Lily sits happiest at around Aquatic; open pond conditions humidity and 24-32°C (75-90°F). A pond plant suited to humid tropical and subtropical climates outdoors. Flowers open above the water surface during daylight. Not grown indoors under normal conditions. If you keep the room above 24 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 blue star water lily sparingly. Press aquatic fertiliser tablets (e.g., Lotus/Lily slow-release tabs) into the planting basket soil at the start of the growing season and every 6-8 weeks thereafter during active growth. Stop fertilising in autumn as growth slows. 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 blue star water lily in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Few or no flowers — Most commonly due to insufficient sunlight or nitrogen-heavy fertiliser promoting leaf over flower growth; move to a sunnier position and use a phosphorus-rich pond fertiliser.
  • Leaf scorch on edges — Caused by splashing or chemical spray contact; ensure leaves float freely on the surface and avoid pond-side pesticide use.
  • Water lily aphids — Treat by submerging affected leaves briefly; biological controls such as releasing ladybirds nearby are effective in gardens.
  • Rhizome rot — Usually caused by cold water or waterlogged heavy clay; replant in fresh aquatic compost and ensure water temperature stays above 20°C.
  • Overcrowding surface — Divide every 2-3 years in spring; aim for leaves covering no more than 50-60% of pond surface for a healthy ecosystem balance.

Companion plants

Blue Star Water Lily pairs well with Nelumbo nucifera, Pistia stratiotes, and Hydrocleys nymphoides. 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

Divide rhizomes in spring when growth is active; cut sections with 2-3 eyes (growth buds) using a clean knife, allow cut surfaces to dry briefly, and replant in fresh aquatic compost. Some varieties also propagate from leaf plantlets that form at the junction of leaf and stem. 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

Blue Star Water Lily is mildly toxic to pets. Nymphaea stellata is not individually listed by the ASPCA. Water lilies (Nymphaea spp.) may cause mild gastrointestinal irritation if ingested by pets due to alkaloid content. The risk is considered low, but the plant should not be confused with the highly toxic Lilium (true lily) genus; seek veterinary advice if significant ingestion occurs. 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.

Blue Star Water Lily care — frequently asked questions

What is the common name for Nymphaea stellata?

Nymphaea stellata is most commonly called Blue Star Water Lily, but it is also known as Blue Star Water Lily, Star Lotus, Blue Lotus. The names refer to the same species, so care instructions for Blue Star Water Lily apply identically to anything sold as Star Lotus.

How much light does blue star water lily need?

Blue Star Water Lily grows best in direct sun (at least 4-6 hours). Requires full sun — a minimum of 5-6 hours of direct sunlight daily for reliable flowering. In partial shade, plants grow but rarely bloom. Ideal for open ponds, water features, or large tubs in sunny gardens.

How often should I water blue star water lily?

Water blue star water lily fully aquatic; roots and tuber submerged, leaves and flowers floating or emergent. Thrives in still or gently moving freshwater, pH 6.5-8.0, temperature 24-32°C. Plant in ponds at a depth of 30-60 cm over the tuber crown. Tolerates warm water better than many water lilies and blooms profusely in tropical summers. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is blue star water lily toxic to cats and dogs?

Blue Star Water Lily is mildly toxic to pets. Nymphaea stellata is not individually listed by the ASPCA. Water lilies (Nymphaea spp.) may cause mild gastrointestinal irritation if ingested by pets due to alkaloid content. The risk is considered low, but the plant should not be confused with the highly toxic Lilium (true lily) genus; seek veterinary advice if significant ingestion occurs.

What USDA hardiness zone does blue star water lily grow in?

Blue Star Water Lily is rated for USDA zone 9-12 (outdoor ponds; overwinter tubers above 10°C in colder climates) and RHS hardiness H1b. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Blue Star Water Lily deep-dive guides

Every aspect of blue star water lily care, each with its own calibrated guide:

Featured in these plant shortlists

Blue Star Water Lily qualifies for 2 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Blue Star Water Lily is also known as Blue Star Water Lily, Star Lotus, and Blue Lotus.