Propagating Persicaria sp. 'Sao Paulo' from Cuttings

A practical guide to multiplying the fine pink-orange stem plant Persicaria 'Sao Paulo' by cuttings, with light, CO2 and trimming advice for vivid background color.

Overview

Persicaria belongs to the knotweed family Polygonaceae and was segregated from Polygonum, which is why this plant is sold both as Persicaria sp. 'Sao Paulo' and Polygonum 'Sao Paulo'. The genus has alternately arranged leaves and stems that are usually erect and self-supporting.

'Sao Paulo' is a controlled, fairly straight-growing stem plant: it has small ridged leaves that stay light green with red-to-maroon stems and flush bright pink-orange under strong light, making it a colorful background plant.

Propagation Method (Cuttings)

'Sao Paulo' is propagated through cuttings — aquarists routinely triple the number of stems from a single plant this way. As with any stem plant, you cut the top few centimetres of a stem and plant it directly into the substrate, where new buds and roots form at the internodes.

Step-by-Step

Select tall, well-colored stems and cut the top 5–10 cm with sharp scissors.
Strip the lowest 2–3 cm of leaves so the buried node stays clean.
Push each cutting a few centimetres into the substrate, keeping a little space between stems instead of one dense bunch.
Leave the trimmed bases — removing the apical bud triggers side shoots that bush out the planting.
Replant the colorful tops where you want fresh, vivid growth at the back of the layout.

Conditions for Healthy Growth

'Sao Paulo' is a moderate-difficulty plant. Its pink-orange flush depends on strong light, and like other stem plants it shows much more pronounced branching in CO2-injected tanks; higher nutrient, CO2 and light levels all promote bushier growth. It converts from emersed to submersed form and then grows actively under good conditions.

Trimming & Maintenance

As a fast background plant it needs frequent topping. Trim a clump while the lower stems are healthy — once, twice, up to about three times — then replant the tops and discard tired old stems and roots. To even out the canopy, pick out and cut the longest individual strands rather than shearing the whole bush flat.

Common Challenges

Without enough light the plant stays green instead of pink-orange, and shaded lower leaves deteriorate over time. When the bottom of a clump thins out, replant the healthy tops rather than trimming yet again.