Propagating Tonina fluviatilis by Cuttings

An advanced guide to propagating the demanding star plant Tonina fluviatilis by cuttings, with the very soft, low-KH, low-pH, high-CO2 conditions it needs to survive.

Overview

Tonina fluviatilis, the star plant, is a South American stem plant of the Eriocaulaceae family with star-shaped rosettes of narrow leaves at each node. It is widely regarded as difficult and is an advanced-only plant: it demands very soft, acidic water and rich CO2, and it can collapse if those conditions swing.

Propagation succeeds only once the plant is genuinely thriving. With strong light, rich CO2 and adequate ferts, leaves stay green far down the stem, growth can be quick — up to several centimetres a week at low KH — and the plant forms side shoots that become cutting stock.

Propagation Method (Cuttings)

Tonina is multiplied by cuttings. You top a healthy, actively growing stem and replant the upper portion; the base then produces side shoots that you can later separate. The key is not the cutting technique itself but maintaining the soft, acidic, CO2-rich water that lets a cutting recover instead of melting.

Step-by-Step

1. Work only with a vigorous stem that is growing actively and staying green down its length.
2. Cut the top 5-10 cm with clean scissors, just above a node on the parent so the base can branch.
3. Remove the lowest rosette or two to expose a clean node for rooting.
4. Replant the cutting into nutrient-rich (peat-based) substrate without disturbing the soft-water chemistry.
5. Hold KH below 4 (ideally 0-2), pH at or below 6.5, with high CO2 and strong light while the cutting establishes.

Conditions for Healthy Growth

KH is the critical parameter: keep it low, below 4 dKH and ideally 0-2, while GH is far less important. pH must sit at 6.5 or lower. Pair this with very rich CO2 and high light. A nutrient-rich, peat-based aquasoil performs better than inert substrate. All Tonina species share this same low-KH, high-CO2, low-pH requirement.

Trimming & Maintenance

Trim every few weeks, around the three-week mark, topping and replanting to keep stems dense and to harvest cuttings. Keep water parameters absolutely stable between trims — sudden changes in KH or pH are far more dangerous to Tonina than the act of cutting itself.

Common Challenges

Browning and melting are the usual failures, almost always traced to KH or pH that drifted too high, or to insufficient CO2. Cuttings will not recover in hard water no matter how cleanly they were taken. Because it is so unforgiving, Tonina is best attempted only after you can hold rock-stable soft, acidic parameters.