Utricularia
Utricularia sandersonii
Utricularia sandersonii: a tiny South African terrestrial bladderwort grown for near-constant small white and lilac flowers rather than for watching it feed.
Utricularia sandersoniiSanderson's bladderwort · Rabbit-ears bladderwort · Angry bunnyFamily Lentibulariaceae
New to these plants? Read the Utricularia group introduction first: it explains what the group is, where the plants grow and how the whole group is cared for.
Quick care
BeginnerDifficulty is an editorial assessment for typical home conditions, not a property of the plant.
- Native range
- Eastern South Africa, in KwaZulu-Natal and the Eastern Cape, at roughly 210 to 1,200 m (700 to 3,900 ft); wet rock faces, seepages and stream-side moss.
- Light
- Bright light with some direct sun, or a grow light. Flowers best in good light.
- Water
- Rain, distilled or reverse-osmosis water. Keep permanently wet by standing the pot in a deep tray or growing it in an undrained bowl.
- Growing medium
- Sphagnum peat moss with sand or perlite, or pure sphagnum, kept wet; proportions are not critical.
- Temperature
- Roughly 15 to 28 °C (59 to 82 °F). Tolerates cooler winters indoors; avoid frost.
- Humidity and airflow
- Moderate; the wet medium supplies most of what it needs.
- Dormancy
- None. Grows and flowers year-round in steady conditions.
- Feeding
- Not needed. The underground bladders catch microscopic animals living in the wet medium. No fertiliser.
Watch out for
- No flowers: usually too little light, or the medium has been allowed to dry.
- Moss or algae covering the surface: harmless but can crowd the tiny leaves; thin it out.
- Plant disappearing from the pot: the medium dried out, or the pot was allowed to stand dry in winter.
- Spreading into neighbouring pots that share a water tray.
- Aphids occasionally settle on the surface leaves.
About this plant
Bladderworts make up the biggest carnivorous plant genus, and their traps are the most sophisticated of all, but you will not see them working. The traps are tiny bladders, a millimetre or two across, on underground stems. Each bladder pumps water out to create a vacuum; when a water flea or other minute creature touches the trigger hairs, a trapdoor opens and the prey is sucked inside in a fraction of a second.
Above ground, Utricularia sandersonii is a carpet of leaves about 1 cm (0.4 in) long and 2 to 3 mm wide, and the whole plant stands only 2 to 4 cm (0.8 to 1.6 in) high. The flowers come on thin stalks 2 to 7 cm (0.8 to 2.8 in) tall, usually one to four to a stalk, each 1 to 1.5 cm (0.4 to 0.6 in) long: white to pale lilac, with a lower lip marked in yellow-green and lilac, a curved spur about as long as the rest of the flower, and two long upper lobes that give the plant its rabbit nicknames. In cultivation it flowers almost continuously.
Light
Bright light encourages flowering. A sunny windowsill with a few hours of direct sun, or a grow light for 12 to 14 hours, suits it. In low light the plant persists but stops flowering.
Water
Keep the medium wet at all times with mineral-poor water. Stand the pot in a deep tray and never let it dry out; the plant has almost no reserves and a dry pot can lose the whole colony. In habitat it grows on dripping rock faces, so there is no such thing as too wet. An undrained bowl works as well as a pot in a tray: wild terrestrial bladderworts sit with the water level at or just above the surface, and flooding the pot from time to time does no harm.
Growing medium
Sphagnum peat moss with sand or perlite, kept saturated, or pure sphagnum, live or dried. The proportions are not critical: anything from equal parts peat and sand to three parts peat to one of sand or perlite works. Shallow pots are fine. Keep fertiliser out of the medium; too much in the soil can kill these plants.
Temperature
Room temperatures are ideal, roughly 15 to 28 °C (59 to 82 °F). It tolerates cooler conditions in winter and may survive a light frost, but it is safest kept above about 5 °C (41 °F).
Dormancy
None. In stable indoor conditions the plant grows and flowers year-round. In winter light it may slow and flower less.
Feeding
Nothing is required. The bladders catch microscopic animals that live in any wet medium, fungus-gnat larvae among them, and the plant takes what it needs. There is no useful way to feed it by hand. Some growers mist terrestrial bladderworts with fertiliser at about a quarter of the label strength, roughly monthly in the growing season, but fertiliser reaching the medium can kill the plants, so the safest course is none.
Repotting
Repot when the colony fills the pot, roughly every one to two years, ideally at the start of the growing season. Propagation is simply division: cut a plug of the moss-like growth with its medium and set it into a new wet pot, where it spreads to fill the space. Alternatively, lift half the contents of the pot and backfill with fresh medium. It will also colonise any neighbouring pot that shares its water tray.
Common problems
A dry pot is the main danger. Otherwise the plant is close to trouble-free. A green film of algae on the surface is harmless; a thick layer of moss can be thinned if it starts to shade the leaves. Aphids sometimes settle on the surface leaves; they are easy to see against the pale green carpet.
Species-specific notes
Several terrestrial bladderworts are grown in the same way, including Utricularia livida and Utricularia bisquamata. Utricularia sandersonii is the one most often recommended for beginners because it flowers so freely. It is vigorous enough to have escaped: small naturalised populations are recorded in the Blue Mountains of New South Wales and on New Zealand’s Coromandel Peninsula. A form with broader, bluer flowers is also in cultivation; unlike the typical plant, it sends thread-like runners into neighbouring pots.
Sources
References for the facts on this page.
- International Carnivorous Plant Society: Growing Genlisea and terrestrial Utricularia (accessed )
- RHS: Utricularia sandersonii (accessed )
- Kew Plants of the World Online: Utricularia sandersonii (accessed )
- Conn, Brown and Fairley (2004) Utricularia sandersonii (Lentibulariaceae), a new record for Australia. Telopea 10(4): 811-814, Royal Botanic Gardens Sydney (accessed )
- New Zealand Plant Conservation Network: Utricularia sandersonii (accessed )
- Rice, B. (1994) Utricularia sandersonii, Bulletin of the Australian Carnivorous Plant Society, reproduced on the author's site (accessed )
- Peter D'Amato, The Savage Garden, Revised Edition (Ten Speed Press, 2013), The Bladderworts chapter. ISBN 978-1-60774-410-8