Cape Sundew Care: How to Grow Drosera capensis

The Cape sundew is the plant we recommend when someone has grown a butterwort successfully and wants something that behaves differently. Drosera capensis is just as forgiving, but it wants the one thing Mexican Pinguicula emphatically do not: a pot that never dries out. Here is how we grow ours.

How sundews differ from butterworts

Most of our growing notes are about Mexican Pinguicula, and it is worth being explicit about where sundew care diverges, because following butterwort advice will slowly kill a sundew.

Pinguicula are not bog plants. They prefer to dry out slightly between waterings — more succulent than swamp. Cape sundews are the opposite: they grow in permanently damp ground and are watered from below, with the pot standing in a tray. A butterwort left in standing water will rot. A sundew left to dry out will collapse.

The second difference is the trap. A butterwort catches insects on a flat, sticky leaf and digests them where they land. A sundew catches them on dew-tipped tentacles, then slowly curls the leaf around the prey to bring more glands into contact with it. It is the same job done with more theatre, and it is genuinely fun to watch.

The third is dormancy. Many Mexican Pinguicula shift to a non-carnivorous winter rosette — the subject of a separate note. Cape sundews do not. They may slow down in cooler months but they keep their carnivorous leaves and need no winter rest.

Light

Full sun to bright indirect. More light does two things: it drives dew production, and it brings out the colour. Our red form flushes crimson from the stem to the tentacle tips under strong light and stays green in dimmer conditions.

A south or west windowsill works well, as does a shelf under full-spectrum LEDs. Sundews tolerate more direct sun than butterworts do, so this is one case where you can push the light harder than you would with a Pinguicula.

Water: the tray method

This is the part that matters most. Stand the pot in a shallow tray with about an inch of distilled or rain water in it, and top the tray up as it is drawn down. The soil should stay wet, not merely moist, through the whole growing season.

Use distilled, rain, or reverse-osmosis water only — never tap. The dissolved minerals in tap water accumulate in the mix and damage the roots, and because sundews sit in water continuously they accumulate those minerals faster than any other plant we sell. This is the single most common way a Cape sundew dies.

In winter, when growth slows, you can let the tray run dry for a day or two between top-ups. Do not let the mix itself dry out completely.

Soil

A 1:1 blend of peat and perlite. That is the whole recipe. Do not use potting compost, do not add fertiliser, and do not use anything containing lime or added nutrients — sundews are adapted to nutrient-poor, acidic ground and ordinary potting mix will burn the roots.

Pots can be deeper than you would use for a butterwort. Cape sundews build a substantial root system and are happy in a 3 to 4 inch pot as they mature.

Humidity and air

Cape sundews are far less humidity-dependent than their appearance suggests. Anywhere from about 30 to 80 percent is fine, which covers most homes. They do not need a terrarium.

If your plant looks dewless in a dry room, the usual culprit is light rather than humidity. Dew production is driven mostly by how much light the plant is getting. Very dry moving air — directly above a radiator, or in front of an air conditioning vent — can reduce dew, so move the plant rather than reaching for a humidifier.

Feeding and what it catches

A Cape sundew on a windowsill will feed itself. The dew-tipped leaves trap fungus gnats, fruit flies, and other small insects on contact, which makes them useful in the same rooms a butterwort earns its keep — with the advantage that a sundew wants a wet pot, so it suits growers already watering on a tray.

Never fertilise the soil. If a plant is genuinely catching nothing, it is easier to move it near the pots that produce gnats than to feed it by hand.

Flowers and seed

Cape sundews send up tall stalks of small pink flowers through the growing season. They are self-pollinating and set seed freely, which is how ours are grown — every plant we ship is seed-grown rather than divided.

If you do not want seedlings appearing in neighbouring pots, snip the flower stalk once it has finished. If you do want more plants, let it go: sown on the surface of damp mix, the seed germinates readily and gives you a shelf of sundews within a year. This is the easiest carnivorous plant to multiply that we grow, and unlike Pinguicula it is not done from leaf pullings.

Why yours may not be red

Almost always light. The red form carries the genetics for deep crimson colouring, but the pigment only develops under strong light. In moderate light the plant grows perfectly well and stays green with red tentacles; under strong light the whole plant colours up.

Give it the brightest position you have and be patient — the colour develops over weeks of new growth, not overnight, and existing green leaves will not turn.

Common problems

• No dew: not enough light, or tap water damage. Check both, starting with light.
• Blackening leaves: older leaves blacken and die back naturally as new ones unfurl. If new growth is blackening too, suspect water quality.
• Wilting: the tray ran dry. Cape sundews do not tolerate drying out the way butterworts do.
• Leaf curled shut and staying shut: that is a leaf digesting something. It will reopen in a few days.

Common questions

Is Drosera capensis safe around pets and children?

Yes. Sundews are non-toxic, and the dew-tipped leaves only catch small insects.

Does it need a dormancy period?

No. Cape sundews are subtropical and grow year-round. They may slow in cooler months but they keep their carnivorous leaves and need no winter rest, unlike temperate sundews and Venus flytraps.

Can I use tap water if I let it stand overnight?

No. Standing water off releases chlorine but does nothing about dissolved minerals, and minerals are the problem. Because a sundew sits in its water continuously, tap water damages it faster than it would a butterwort.

Why is the dew not evaporating in dry air?

It is not water. The droplets are a sticky mucilage produced by the plant's glands, so they persist in dry rooms and reform after rain or after the plant has fed.

How big does it get?

Leaves reach several inches long on a mature plant, forming a loose rosette rather than the flat pinwheel a butterwort makes. Give it a pot a size larger than you would a Pinguicula.

Can I grow it in the same tray as my butterworts?

Not comfortably. Sundews want to stand in water continuously and butterworts do not, so they need separate trays even if they share a windowsill.

Where to go next

If you are coming to sundews from butterworts, our guide to choosing your first Mexican butterwort covers the other side of the collection, and the Pinguicula care guide is the reference for those. Both genera are equally effective against fungus gnats.

Shop sundews →