Alisma plantago-aquatica
Water plantain
Common names: European water plantain, Mad-dog weed
At a glance
- Light
- Full sun
- Pot size
- from 50 l
- Lifespan
- Perennial
- Flowering
- Jun–Sep
- Hardiness
- Hardy
- Origin
- Native to Germany
Photo: Christian Fischer · CC BY-SA 3.0 · Source
Description
Alisma plantago‑aquatica, commonly known as frog’s‑bit, is a native riparian plant that produces conspicuous, loose white flower spikes that float above grass‑like leaf rosettes from June to September. It prefers shallow water at pond margins or permanently wet marsh zones, where it readily spreads to form natural stands. The plant attracts insects such as hoverflies and bees, making it a valuable component of naturalistic pond gardens. The plant is toxic; fresh sap contains irritants that can affect skin and mucous membranes, so it should not be consumed and gloves are recommended when handling or propagating.
Care instructions
Frog’s‑bit thrives best in shallow water 5 to 20 cm deep over the root ball, or in a pot with loamy pond soil. Place it in a sunny to partially shaded spot on the bank for most reliable flowering. Deadhead spent spikes in late summer to control seed spread and keep the plant compact. The root mass remains frost‑free underwater in winter; pruning dead leaves in spring is sufficient maintenance. Divide larger clumps every few years in spring to rejuvenate the stand and prevent uncontrolled spread in the pond.
The care notes were machine-translated from German.
Garden year
FloweringJun–Sep
Soil & site
Soil pH
Soil type
moist, nutrient-rich, loamy, clayey
Water plantain prefers to grow with its roots directly in the water or in permanently wet mud at the pond edge. A nutrient-rich, loamy to clayey base gives it the support and the nutrients it needs for its strong leaves. Waterlogging is not a problem here but the basic requirement; an ordinary garden bed is unsuitable for it.
Feeding
Medium feeder
Months
May–Jun
In a pond, the natural nutrients from dead plant material and sediment are usually quite enough. If you would like to feed in addition, work a little mature compost into the planting baskets or the bank mud in late spring. Avoid mineral fertiliser at the pond, as it pollutes the water and promotes algae.
Overwintering
Water plantain is hardy and withdraws in autumn; the above-ground leaves die and can be cut off. As long as the rootstock sits below the frost line in the water or mud, it survives even harsh winters without problems. In shallow ponds or tubs it is worth sinking the planting basket deeper, so that the roots do not freeze through.
Propagation
Methods
- From seed
- Division
The easiest way is to divide the rootstock in spring and put the pieces straight into new planting baskets. Water plantain also likes to self-seed: the fine seeds ripen on the tall flower heads and fall into the water, where they germinate in the moist mud. If you want to propagate deliberately, collect the ripe seed heads in late summer and scatter them directly on moist ground or in shallow water. Patience pays off: it often takes two years until the first flowering.
For your garden
Grow Water plantain yourself
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