Cape Sundew Care: How to Grow Drosera capensis

The Cape sundew is the plant we suggest to someone who has kept a butterwort alive and wants something different. Drosera capensis is just as forgiving, but it wants the one thing a Mexican butterwort will not tolerate: a pot that never dries out. This is how we grow ours, and where sundew care parts ways with butterwort care.

Where sundews and butterworts differ

Most of what we write is about Mexican Pinguicula, and the differences matter, because following butterwort advice will slowly kill a sundew.

Butterworts are not bog plants. They like to dry out a little between waterings. Cape sundews grow in permanently wet ground in the Western Cape of South Africa, and in a pot they are watered from below, standing in a tray. A butterwort left in standing water rots. A sundew left to dry out collapses.

The trap is different too. A butterwort holds an insect flat against a sticky leaf and digests it where it landed. A sundew catches it on dew-tipped tentacles, then folds the leaf around it over a few hours to bring more glands into contact. You can watch it happen.

The third difference is winter. Many Mexican butterworts switch to a non-carnivorous winter rosette, which we cover in a separate note. Cape sundews do not. They slow down in cooler months but keep their sticky leaves and need no rest.

Light

Full sun to bright indirect. More light means more dew and more color. Our red form colors crimson from the stem to the tentacle tips under strong light and stays mostly green in dimmer spots.

A south or west window works, and so does a shelf under full-spectrum LEDs. Sundews handle more direct sun than butterworts, so this is one plant you can push harder on light.

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 rainwater and top the tray up as the plant draws it down. Through the growing season the mix should stay wet, not just moist.

Use distilled, reverse-osmosis or rainwater and nothing else. Minerals in tap water build up in the mix and damage the roots, and because a sundew sits in its water all the time, it accumulates them faster than any other plant we sell. Tap water is the most common reason a Cape sundew dies.

In winter, when growth slows, the tray can go dry for a day or two between top-ups. The mix itself should never dry out completely.

Soil

A 1:1 blend of peat moss and perlite. That is the whole recipe. No potting soil, no fertilizer, nothing with lime or added nutrients. Sundews come from acidic, nutrient-poor ground, and ordinary potting mix burns the roots.

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

Humidity and air

Cape sundews need far less humidity than they look like they should. Anywhere from about 30 to 80 percent is fine, which covers most homes, and they do not need a terrarium.

If the plant has no dew in a dry room, the cause is usually light rather than humidity. Very dry moving air, right above a radiator or in front of an air-conditioning vent, can reduce dew, so move the plant rather than buying a humidifier.

Feeding

A Cape sundew on a windowsill feeds itself. The leaves trap fungus gnats, fruit flies and other small insects on contact, so it does the same job as a butterwort in a room full of houseplants, and it suits anyone who already waters on a tray.

Never put fertilizer in the soil. If the plant is catching nothing at all, move it closer to the pots the gnats are coming from.

Flowers and seed

Through the growing season a Cape sundew sends up tall stalks of small pink flowers. They pollinate themselves and set seed freely. Every plant we ship is grown from seed.

If you do not want seedlings popping up in neighboring pots, snip the stalk once it has finished flowering. If you want more plants, let it go. Seed sown on the surface of wet mix germinates readily, and you can have a shelf of sundews within a year. It is the easiest plant we grow to multiply. Leaf cuttings floated on water and root cuttings also work, but seed is simpler, and the leaf pulling method we use for butterworts does not apply.

Why yours may not be red

Almost always light. The red form carries the genes for deep crimson, but the pigment only builds under strong light. In moderate light the plant grows well and stays green with red tentacles. Under strong light the whole plant colors.

Give it the brightest spot you have and wait. Color develops over weeks of new growth, and leaves that grew green stay green.

Common problems

• No dew. Not enough light, or tap water damage. Check light first.
• Blackening leaves. Old leaves blacken and die back as new ones unfurl. If new growth is blackening too, suspect the water.
• Wilting. The tray ran dry. A Cape sundew does not tolerate drying out the way a butterwort does.
• A leaf curled shut and staying shut. It is digesting something. It reopens in a few days.

Common questions

Is Drosera capensis safe around pets and children?

Yes. Sundews are not toxic, and the sticky tentacles only hold small insects.

Does it need a dormancy period?

No. Cape sundews are subtropical and grow year-round. They slow in cooler months but keep their leaves, unlike temperate sundews and Venus flytraps, which need a cold rest.

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

No. Standing lets chlorine escape and leaves every mineral behind. Because a sundew sits in its water continuously, tap water hurts it faster than it hurts a butterwort.

Why does the dew not evaporate in dry air?

Because it is not water. Each droplet is a sticky mucilage the plant secretes, so it holds up in a dry room and is replaced after the plant has fed or a leaf has been rinsed.

How big does it get?

A mature plant carries leaves several inches long in a loose, upright rosette, taller than the flat pinwheel of a butterwort. Give it a pot one size larger than you would a Pinguicula.

Can it share a tray with my butterworts?

Not comfortably. Sundews want to stand in water all the time and butterworts do not, so give them separate trays even if they share a windowsill.

Where to go next

If you came to sundews from butterworts, our guide to choosing your first Mexican butterwort covers that side of the collection, and the Pinguicula care guide is the full reference. Both genera work against fungus gnats.

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