Trichocereus hahnianus | Live plant

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A harder-to-find Trichocereus species from Paraguay. Live plant.

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Trichocereus hahnianus | Live plant

(syn. Echinopsis hahniana, Harrisia hahniana, Mediocactus hahnianus, Soehrensia hahniana)

After much searching, we eventually managed to obtain some of the elusive Trichocereus hahnianus cacti – available from our shop as live, rooted plants!

Trichocereus hahnianus (synonymous with Echinopsis hahniana, Harrisia hahniana, Mediocactus hahnianus and Soehrensia hahniana) is a rather novel species which is native to Paraguay. It’s named after the German horticulturist Adolph Hahn, as the species was described by Curt Backeberg using Hahn’s plant as reference. However, there are no known plants or herbarium specimens extant from the original collection that this plant would have necessarily derived from.

Compared to the many of its relatives among the Trichocereus genus, this plant’s growth habit is quite distinct, as it tends toward creeping, pendulous or prostrate form, putting out new roots from parts of its stems which make contact with soil. It’s actually somewhat reminiscent in appearance to several Selenicereus species, in our view. Stems – up to roughly three centimetres in diameter and one-metre or so in length – are relatively fragile, bright to dark green in colour and typically form eight shallow ribs. Spination is moderate (nine to twelve spines), thin, up to approximately two-and-a-half-centimetres in length and whitish-yellowish-brownish-red in colour.

Younger areas of stems produce nocturnal, white-whitish-cream-tan-coloured flowers, relatively small (roughly twelve-centimetres in diameter once fully open) and with a pleasant aroma. Hahnianus bears reddish-green, ovoid fruit – hairy, lightly-thorned and approximately three-centimetres long by two-centimetres diameter (at its broadest point).

Some researchers believe hahnianus to form part of a clade with Trichocereus bridgesii (also known as the ‘Bolivian Torch’ cactus), Trichocereus camarguensis, Trichocereus thelegonus and Trichocereus vasquezii, which all share a specific chromosome (2n = 22, apparently). The species is currently listed in the IUCN’s Red List of Threatened Species as “Data Deficient”.

In general, hahnianus prefers to grow naturally in USDA Hardiness Zones ten and eleven, on limestone rocks, at between two-hundred and five-hundred metres above sea level. The locality type of a more recent hahnianus collection grows in the thin, alkaline clay of shady, dry woodland around the Department Presidente Hayes, situated within the vast, yet sparsely-populated, Chaco region, north-eastern Paraguay. However, the original collection, made roughly four-hundred kilometres away, in the Río Apa (Apa River) zone, grows in an area which reportedly receives an average of five-hundred millimetres more annual rainfall than does the one at Department Presidente Hayes.

We’ve only been cultivating this species for a short time as of writing, but it seems to respond well to similar treatment to its fellow Trichocereus species so far. We plant ours in a mildly-alkaline to mildly-acidic, well-drained mix of equal parts soil and perlite (or similar), watering only when the top few centimetres of soil have dried out completely. If planting straight into the ground, make sure to leave roughly a metre to a metre-and-a-half between plants, so they have enough room to spread out. Lightly fertilise two or three times each year and avoid frosts and you can expect to enjoy the company of this elusive species for many years to come!

Product Details

Product Type

Live plant


1 rooted plant


~10 cm tall, ~21 cm tall







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