Onion plant

Crinum calamistratum

Also known as African onion plant, Curly crinum, Crinum natans var. calamistratum

FreshwaterBulb / tuberBulb offsets

Onion plant (Crinum calamistratum) — Krzysztof Ziarnek, Kenraiz · CC BY-SA 4.0

Care at a glance

Light: Low light
CO2: No CO₂ needed
Growth rate: Slow
Placement: Background
Type: Bulb / tuber
Temperature: 68–82°F (20–28°C)
pH: 6.0–8.0
Hardness: 2–15 dGH
Max height: 23.6 in (60 cm)
Spread: 9.8 in (25 cm)
Nutrient uptake: Root feeder
Growth region: Submersed
Difficulty: Easy
Origin: West-Central Africa (Cameroon)
Family: Amaryllidaceae

Overview

Plant the bulb at an angle with the top third left proud of the substrate so it does not rot, and be patient because it establishes and grows slowly. It is a heavy root feeder, so root tabs or a rich substrate keep the curly leaves dark and healthy, and it does not need CO2. The tough leaves are ignored by most plant-eating and cichlid-type fish, which makes it a durable centrepiece or background specimen for large tanks.

In the wild

Crinum calamistratum comes from West-Central Africa, growing in fast-flowing forest streams and rivers around Cameroon near Kumba. It roots as a bulb in the streambed and trails long, dark green, strongly crinkled ribbon leaves in the current. It lives fully submersed and, unlike some Crinum relatives, does not adapt to emersed growth.

Good to know

It is a true bulb-forming member of the amaryllis family (Amaryllidaceae), related to terrestrial garden lilies rather than to typical stem or rosette aquarium plants. The name calamistratum refers to the curled, crimped leaves ('curled like with a curling iron'). It forms several smaller bulbs and, unlike the larger-bulbed Crinum species, is undemanding on light while responding to brighter tanks with more compact, flower-prone growth.

Did you know

Given enough time and space, Crinum calamistratum will send up a stalk and bloom underwater or at the surface with a spidery white amaryllis-style flower, something few aquarium plants do.