Persicaria Praetermissa

Quick facts

Identity

Also known as

Ruby Smartweed; Polygonum Ruby

Synonyms

Polygonum sp. 'Ruby'; Polygonum praetermissum; Persicaria sp. Ruby

Environment

Freshwater

Native to

Tropical Asia, Australia

Habitat

Marshes, wet ditches and muddy margins of still or slow-moving water, growing amphibiously emersed on wet ground or fully submersed when flooded

Sourcing

Aquacultured

Conservation

Not Evaluated

Care

Care level

Moderate

Growth form

Stem

Max height

3 – 14 in (7.6 – 36 cm)

Spread

6 in (15 cm)

Growth rate

Fast

Placement

Midground, Background

Water

Temperature

64 – 86 °F (18 – 30 °C)

pH

5.0 – 7.0

GH

2 – 6 dGH

dKH

0 – 14 dKH

Flow

Moderate

Light

Medium

CO₂

Beneficial

Planting

Substrate

Nutrient-rich preferred

Feeds from

Both

Fertilizer needs

Medium

Colors

Red, Brown, Orange

Feeding & breeding

Propagation

Cuttings

Something wrong or missing? Submit a correction

Care guide

Overview

Narrow, spearhead-shaped leaves take on copper, magenta and reddish-brown hues underwater, deepest under strong light and steady CO2. Growth leans diagonally rather than upright, letting stems drape over hardscape and fill the midground. Fast growing and shrimp safe, it wants a nutrient-rich substrate and regular thinning to keep lower leaves from shading out.

Care

This knotweed stands out among stem plants for its diagonal, sprawling growth habit, with shoots leaning sideways rather than racing to the surface, so it fills the midground and drapes over hardscape rather than forming a vertical hedge. Underwater the narrow, spearhead-shaped leaves shift to brown-red or copper tones, most intense under strong light with CO2 and consistent nutrient dosing, though the plant will survive on less at the cost of color and density. It is not a demanding species by the standards of colored Persicaria, but it stalls and fades in dim, lean setups, so plan for moderate to high light and a fertilized substrate.

Planting & trimming

Plant cuttings directly into open substrate, spacing them enough to allow the sprawling shoots room to spread sideways rather than crowding vertically. When a stem wanders too far across the layout, trim it back to a node and replant the cut top to keep growth dense and controlled. It converts readily between emersed and submersed forms, so it can also be grown emersed in paludariums or as a start-up culture before flooding.

Fertilizing

A nutrient-rich substrate supports root development and vigorous growth, since this plant draws nutrients through both roots and the water column. Regular liquid fertilization with iron helps maintain the deeper copper and magenta leaf tones, and pale or washed-out new growth is usually a sign of insufficient iron or light. CO2 injection is strongly recommended, as growth and coloration are noticeably weaker without it.

Propagation

Propagation is by stem cuttings: cut a healthy shoot below a node, remove the lower leaves, and replant the top section in substrate where it will root within a couple of weeks. The original base often continues to branch and produce additional side shoots that can later be harvested as further cuttings.

Problems

Lower leaves can drop or thin out if light or nutrients are inadequate, and stems tend to stretch and lose color in shaded tanks. Because the sparsely branched shoots grow diagonally, lower portions of the plant can become shaded by their own upper growth or by neighboring stems, so periodic thinning helps keep the base healthy. Algae can settle on slower-growing sections in tanks with excess nutrients relative to light and CO2.

Sources

1. Persicaria praetermissa care: light, CO2 and placement · TankBud
2. Persicaria praetermissa - Flowgrow Aquatic Plant Database
3. Persicaria Praetermissa / Ruby aquarium plant | AquaTank Rare Aquarium Plants

More Stem plants

Alternanthera Amabilis TricolorAlternanthera Bettzickiana GreenAlternanthera Bettzickiana RedAlternanthera LilacinaAlternanthera Red Broad LeafAlternanthera Reineckii