Onion Plant

This is a true bulb plant, not a rhizome or tuber, and it behaves like a submerged lily. Crinum thaianum comes from Thailand, where it grows in slow-moving streams and shallow ponds. The bulb can reach the size of a small onion — hence the common name — and the leaves extend as long, wavy ribbons that can exceed one metre in a large tank.

The leaves are dark green, soft, and slightly curled along the edges, growing directly from the bulb in a dense cluster. Unlike many rosette plants, the bulb must not be fully buried — keep the top two thirds of the bulb exposed above the substrate. A nutrient-rich substrate helps, and root tabs near the bulb provide steady feeding.

It is one of the easier large aquarium plants. Moderate light, temperatures from 22 to 29 °C, and pH 5.5 to 8 cover its range without special demands. The main challenge is space: in a 200-litre tank or smaller the plant quickly dominates, shading everything beneath it.

Allow the bulb time to settle and watch for healthy new leaves. Propagation is by bulb offsets — small bulbs form at the base of the parent and can be separated once they have their own roots. It also flowers above the surface, producing white, lily-like blooms.