Lake cress

Rorippa aquatica

Also known as Water horseradish, Water cabbage, Armoracia aquatica, Neobeckia aquatica

FreshwaterStemPlantletsCuttings

Lake cress (Rorippa aquatica) — Aquarium Plants Factory · Used with permission

Care at a glance

Light: Medium light
CO2: No CO₂ needed
Temperature: 64–79°F; 18–26°C
Max height: 5.9 in; 15 cm

Growth rate: Slow
Placement: Midground
Type: Stem
pH: 6.0–7.5
Hardness: 2–15 dGH
Spread: 4.7 in (12 cm)
Nutrient uptake: Root + water column
Growth region: Submersed or emersed
Difficulty: Medium
Family: Brassicaceae
Origin: Native to slow streams, ponds, and swamps of central and eastern North America.

Overview

Lake cress is a slow-growing stem plant for the midground, and it forms a low, feathery rosette underwater. It is a plant of medium difficulty.

Did you know

Lake cress is a favorite of plant scientists. Its leaf shape changes with temperature, and researchers study it to learn how plants control leaf form.

Caring for lake cress

Strip the lower leaves from each stem and push the stems into the substrate one at a time, a little apart. Lake cress belongs in the midground, where it reaches about 6 in (15 cm).

Give it medium light and a rich substrate. It needs no added CO2. It feeds through both its roots and its leaves, so root tabs and a liquid fertilizer together cover it. It prefers cooler water, 64 to 79°F (18 to 26°C).

Growth is slow even under good conditions, so it rarely needs trimming. It spreads mainly from plantlets that form on detached leaves floating at the surface. Collect those and replant them once they have a few roots. Cuttings root as well, and the stump left behind grows new shoots.

Good to know

Lake cress is a member of the mustard family, Brassicaceae, and has also been known as Armoracia aquatica and Neobeckia aquatica. Underwater it grows deeply cut, almost fern-like leaves, while its leaves above water are simpler and toothed. Botanists call this switch heterophylly.

In the wild

Lake cress is native to slow streams, ponds and swamps of central and eastern North America. It grows floating or rooted in the shallow margins.

Common questions

Does lake cress need to be planted in the substrate?

Yes. Strip the leaves from the lower part of each stem, then push the stems into the substrate one at a time, a little apart.

Does lake cress need CO2?

No. Lake cress grows well without added CO2.

How much light does lake cress need?

Lake cress wants medium light. A light sold for planted tanks covers it.

Does lake cress need root tabs?

They help. Lake cress takes nutrients through both its roots and its leaves. Root tabs near its roots and a liquid fertilizer cover both.

How do you propagate lake cress?

Lake cress propagates by plantlets and cuttings. Small plantlets form on the plant and can be detached once they have a few roots. Cut off the top of a stem and replant it, and the stump left behind grows new shoots.