Sundews (genus Drosera) are the jewelers of the carnivorous plant world. Each leaf is studded with glistening, tentacle-like hairs tipped in a clear, sticky dew that catches the light — and catches gnats, fruit flies, and fungus gnats by the dozen. With around 250 species ranging from Arctic bogs to Australian deserts, sundews offer something for every windowsill, and many are genuinely easy once you understand the four rules that govern all carnivorous plants: mineral-free water, nutrient-poor soil, intense light, and (for some) a winter rest. Get those right and a single rosette will sparkle year-round, multiply, and quietly clean fungus gnats out of your other houseplants. This guide covers choosing a species, the exact growing setup, feeding, propagation, and the handful of mistakes that account for nearly every sundew death.
Key Takeaways
- Water with distilled, reverse-osmosis, or rainwater only — never tap, spring, or bottled mineral water. Dissolved minerals accumulate in the peat and kill sundews within weeks.
- Use a lean, acidic mix: roughly 1:1 sphagnum peat moss and perlite or silica sand. No potting soil, compost, or fertilizer ever touches the roots.
- Give bright light — a sunny windowsill, a few inches under a grow light, or full sun outdoors. Strong light brings out red color and heavy dew; weak light produces pale, dewless, floppy leaves.
- Most sundews want high humidity and constantly damp-to-wet roots. Stand the pot in a tray of safe water (the “tray method”).
- Choose your species by climate: subtropical sundews (like D. capensis) grow year-round and are ideal for beginners; temperate species need a cold winter dormancy.
Meet the Sundews: Choosing the Right Drosera
“Sundew” covers a huge, varied genus, and your success starts with picking a species suited to how you can grow it. There are three broad groups worth knowing. Subtropical sundews grow actively all year with no dormancy and are the best entry point — the Cape sundew (Drosera capensis) is the famous beginner plant: nearly indestructible, fast, prolific with seed, and tolerant of average home humidity. The spoon-leaved sundew (D. spatulata) and the forked sundew (D. binata) are similarly forgiving.
Temperate sundews — including the round-leaved sundew (D. rotundifolia) native to North American and European bogs — go fully dormant in winter, often shrinking to a tight resting bud called a hibernaculum. They need a real cold season of around 35-50°F for several months. Tropical and “petiolaris-complex” sundews from northern Australia want constant warmth and very high humidity and are best left until you have some experience. If you are buying your first sundew, get a Cape sundew in green or “all-red” form and learn on that.
Water: The One Rule That Kills Most Sundews
If you remember nothing else, remember this: water sundews only with distilled water, reverse-osmosis (RO) water, or collected rainwater. Tap water, well water, spring water, and bottled “mineral” water all carry dissolved salts and minerals — measured as total dissolved solids, or TDS — that a carnivorous plant cannot process. These plants evolved in rain-fed bogs where the water is essentially pure. Every time you water with mineral-laden water, the salts stay behind in the peat and accumulate. Within weeks to a couple of months the buildup burns the roots, the dew stops forming, leaves brown, and the plant dies — a slow decline owners usually blame on the wrong thing.
Aim for water under about 50 ppm TDS; under 30 is ideal. A cheap TDS meter (sold for aquariums and RO systems) lets you confirm. Distilled water from the grocery store reads near zero, rainwater collected in a clean barrel is free and excellent, and RO water from a home filter is perfect. Most US tap water runs 150-400 ppm and is unsafe for these plants, even if it tastes fine to you. There is no workaround and no “letting it sit out overnight” trick — minerals do not evaporate.
Soil and Pots: Poor on Purpose
Sundews grow in deliberately barren media. Regular potting mix, garden soil, compost, and anything labeled “with feed” or “moisture control” will kill them because they are rich in the nutrients and minerals these plants cannot tolerate. The standard recipe is a 1:1 blend of sphagnum peat moss and perlite, or peat and silica sand. Long-fiber sphagnum moss, alone or mixed with perlite, works beautifully for many sundews and is especially nice for the smaller rosette types. Rinse perlite and sand first to wash out dust and any mineral residue.
Use plastic, glazed ceramic, or glass pots — never unglazed terracotta, which leaches minerals and wicks water away too quickly. Tall pots suit species with deep roots like D. capensis; shallow, wide pots suit ground-hugging rosettes. Because sundews like constant moisture, stand the pot in a tray or saucer holding about half an inch to an inch of your safe water and refill it as the plant drinks — the classic “tray method” keeps the roots evenly wet without your having to remember to water the surface.
Light: The Secret to Dew and Red Color
Light is what makes a sundew sparkle. In strong light the plant produces abundant, heavy dew droplets and, in many species, develops gorgeous red or pink pigmentation as a natural sunscreen. In weak light it makes pale green, floppy, nearly dewless leaves and slowly starves. Give your sundew the brightest spot you can. A south- or west-facing windowsill works for subtropical types. If light is limited, a grow light a few inches above the plant running 12-14 hours a day produces excellent results — sundews respond dramatically to good lighting.
Sundews can also grow outdoors in full sun during the warm months, where they will catch far more prey and color up intensely. If you move an indoor plant outside, acclimate it over a week or two to avoid scorching the tender leaves. One sign your light is too low is “no dew”: a healthy, well-lit sundew should always carry visible droplets, except briefly after it has been disturbed or has just caught a large meal.
Humidity and Temperature
Dew is largely water, so humidity matters. Many subtropical sundews — Cape sundew especially — adapt to ordinary household humidity of 40-50% once established, though they dew more heavily when it is higher. Smaller rosette species and tropical types prefer 60% or more, which is easy to provide in a terrarium, a covered tray, or by grouping plants together. If a newly purchased sundew loses its dew indoors, raising humidity for a week or two while it acclimates usually brings it back.
Temperature needs follow the group: subtropical sundews are happy at normal room temperatures of 65-85°F year-round. Temperate sundews tolerate the same in summer but require a cold dormancy in winter. Tropical species want consistent warmth and dislike dropping below the low 60s. Avoid placing any sundew against a hot, dry windowpane in summer or a freezing one in winter.
Feeding: Let It Hunt
Outdoors and on a sunny sill, sundews feed themselves — they are remarkably effective at trapping fungus gnats, fruit flies, and small flying insects, which is why many indoor gardeners keep one near their other houseplants as living gnat control. You do not need to feed a sundew that is catching prey. Never put fertilizer in the soil and never offer meat, cheese, or human food — the plant cannot digest them and they rot and invite mold.
If you want to feed a plant that is not catching anything, offer tiny prey: a single dried bloodworm (rehydrated with a drop of safe water), a small dried insect, or a freshly killed fruit fly placed on the sticky leaf so the dew can wrap around it. Feed sparingly — once every week or two during active growth is plenty. Overfeeding individual leaves can cause them to blacken and die back, which is normal and not a problem unless the whole plant is suffering. For those who like the science of carnivorous nutrition, our Venus flytrap growing guide covers feeding mechanics in more depth.
Dormancy for Temperate Species
This step applies only to temperate sundews like D. rotundifolia, D. anglica, and D. filiformis. As days shorten in autumn these species naturally slow, lose their dew, and in many cases curl into a tight resting bud (hibernaculum). They need a cold rest of roughly 3-4 months at 35-50°F to survive long-term — a cold but unheated porch, a bright cold windowsill, or even the crisper drawer of a refrigerator (potted and barely moist) all work. Keep them just damp during dormancy, not wet, and reduce light. Skipping dormancy on a temperate sundew leads to a weak plant that exhausts itself within a year. Subtropical and tropical sundews do not need this and should keep growing through winter under lights.
Propagation: More Sundews for Free
Sundews are among the easiest carnivorous plants to multiply. The Cape sundew is famous for setting copious self-pollinated seed; scatter the dust-fine seed on the surface of damp peat-perlite mix, keep it humid and brightly lit, and you will have a tray of seedlings in a few weeks. Leaf cuttings also work for many species: lay a healthy leaf, dewy side up, on damp media or float it in a covered dish of safe water, give it bright light, and tiny plantlets sprout from the leaf within weeks. Mature clumps can also be divided at repotting time. Repot every year or two into fresh mix, since even pure water gradually breaks peat down.
Troubleshooting Common Problems
No dew on the leaves is the most common complaint and usually means light is too low or humidity dropped sharply (often right after purchase). Increase both and give the plant a week to recover. Browning or blackening leaves can be normal leaf turnover, the result of overfeeding a single leaf, or — if widespread and the plant is declining — a sign of mineral buildup from the wrong water. Mold or fungus usually follows uneaten food or poor airflow; remove the debris and improve ventilation. A mushy crown points to rot from soil that stayed soggy and warm with no air movement. If you grow several carnivorous plants together, the same bog-style setup that suits sundews also suits pitcher plants — see our guide to growing pitcher plants for companions in the same tray. For more plant care guides, browse the Plants & Flowers hub.
Frequently Asked Questions
Why does my sundew have no sticky dew?
Almost always too little light or a sudden drop in humidity — common right after you bring a plant home. Move it to your brightest window or a few inches under a grow light running 12-14 hours, raise humidity for a week or two, and the dew typically returns once the plant settles in.
Can I water my sundew with tap water?
No. Tap, well, spring, and bottled mineral water all contain dissolved minerals that accumulate in the peat and kill carnivorous plants. Use only distilled, reverse-osmosis, or rainwater, ideally under 50 ppm TDS. There is no safe workaround for hard tap water.
Do I need to feed my sundew?
Usually not. A well-lit sundew catches its own gnats and small flies. If it is not catching anything, offer tiny prey such as a rehydrated bloodworm or a fruit fly once every week or two. Never use fertilizer or human food, which rot and harm the plant.
Which sundew is best for beginners?
The Cape sundew (Drosera capensis) is the classic starter — fast, forgiving of average humidity, grows year-round with no dormancy, and self-seeds prolifically. The spoon-leaved sundew (D. spatulata) is another easy choice. Avoid temperate and tropical species until you have some experience.
Do all sundews need a winter dormancy?
No. Only temperate species like D. rotundifolia and D. filiformis need a cold rest of 3-4 months at 35-50°F. Subtropical and tropical sundews grow continuously and should be kept warm and lit through winter — giving them a cold dormancy would harm them.