Begonia pseudoedulis „Shiwanshan“ - Care

Bright to partial shade with plenty of indirect light, similar to the filtered light under a forest canopy, allows the Shiwanshan to grow most vigorously. You should avoid direct sun, as the leaves will burn quickly. If there is a lack of light, growth will be noticeably weaker and the leaves will remain smaller than with sufficient lighting.

The substrate should be kept evenly lightly moist, without ever becoming waterlogged – water again as soon as the top 1 to 2 cm have dried out. Shiwanshan reacts to waterlogging and prolonged dry spells with wilting leaves or rotten spots on the rhizome, so a consistent watering schedule is more important than with hardier houseplants. Room-temperature, low-lime water is best tolerated; always pour off excess water from saucers or cachepots. In autumn and winter, when growth slows down, watering is noticeably reduced.

If Shiwanshan is actively growing and producing new, large leaves, you can provide it with a highly diluted liquid fertilizer every 3 to 4 weeks during its growth phase (one quarter to a maximum of half the recommended amount). Since it produces significantly larger leaves compared to many small terrarium begonias, it can tolerate slightly more nutrients, but it remains sensitive to high salt concentrations. A general guideline for begonias is a pH of about 5.2 to 6.0 and rather low values of 0.5 to 1.3 mS/cm. Follow the manufacturer's instructions on the respective packaging for precise dosage. If the plant is only placed by the window in autumn and winter, the light will be weaker, and fertilization should be reduced accordingly or paused. However, if it grows year-round under sufficiently bright plant lights, the usual rhythm can be maintained without further reductions.

We consciously alternate between different fertilizers for our own plants – currently including COMPO COMPLETE, Foliage Focus, Liquid Gold Leaf, and Hesi TNT-Complex, supplemented with Hesi Root Complex, Hesi PowerZyme, and CalMag as needed.

A loose, well-draining yet moisture-retaining substrate is most suitable for the Shiwanshan – a mix of potting soil, perlite, and some bark or sphagnum moss works well. Repot approximately every 1 to 2 years or as soon as the rhizome visibly grows over the edge of the pot; choose a pot that is only slightly larger than the existing root ball so that the substrate does not remain wet for too long.

Unlike many true terrarium begonias, the Shiwanshan can also be grown outside of a closed terrarium in a normal living space, but it grows noticeably more vigorously and produces larger, plumper-looking leaves when the humidity is higher, starting at around 60 %. In persistently dry, heated air, it tends to develop brown leaf edges. A humidifier or a location with consistently higher humidity will help alleviate this. In terms of temperature, it prefers consistent warmth year-round, ideally between 18 and 26 °C; it does not tolerate sudden temperature fluctuations or cold drafts well and reacts to them by shedding leaves.

In contrast to many compact terrarium begonias, Shiwanshan does not stay tiny: under good conditions, it develops into a stately plant with large, decorative leaves and can certainly become an eye-catcher on your shelf. It grows rhizomatously, meaning via a creeping, ground-level rhizome from which new leaves and roots constantly emerge. Botanically discovered only in 2021 and scientifically described in 2023, the species is still relatively new in commerce. A distinct dormancy period has not been documented, but it grows noticeably slower in winter.