Callitriche palustris
Water star
Common names: Swamp water star
At a glance
- Light
- Full sun
- Pot size
- from 50 l
- Lifespan
- Perennial
- Flowering
- May–Aug
- Hardiness
- Hardy
- Origin
- Native to Germany
Photo: Christian Fischer · CC BY-SA 3.0 · Source
This description was machine-translated.
Description
The water star (Callitriche palustris) is a native submerged plant that forms small, star‑shaped leaf rosettes at the water surface in ponds and shallow water zones. It is one of the most reliable oxygenators in garden ponds, helping to keep the water noticeably clearer. Tiny, inconspicuous flowers appear between May and August, providing food for microscopic organisms. The plant remains low and grows densely, making it suitable for small ponds and ornamental water features.
Care instructions
Plant the water star in shallow water zones up to about 30 cm deep, preferably directly in planting baskets with loamy substrate and no fertilizer. A sunny to partially shaded location promotes dense growth and high oxygen output. Trim excess shoots in spring and summer before they overrun the pond, and regularly remove dead plant material from the water. The water star is hardy; it retreats in autumn and re‑emerges in early spring, around week 12 to 15 of the year.
The care notes were machine-translated from German.
Garden year
FloweringMay–Aug
Soil & site
Soil pH
Soil type
moist, humus-rich, nutrient-rich, loamy
The common water-starwort grows submerged or floating in still to slowly flowing waters with a soft, nutrient-rich muddy bed. A humus-rich, fine substrate on the bottom of the water is quite enough as a root anchor. Look for clear water that is not too chalky, and the plant forms dense underwater lawns. It tolerates heavy silting or foul sludge poorly.
Feeding
Light feeder
In an established garden pond the common water-starwort needs no additional feeding; it draws its nutrients directly from the water and the substrate. Pond water that is too rich in nutrients encourages algae rather than the plant itself, so it is better to stay restrained. A little mature compost in the planting basket when planting is enough for a good start. You should generally avoid mineral or synthetic fertilisers in the pond.
Overwintering
The common water-starwort is hardy and usually survives the cold season as a rosette on the bed of the water, as long as the water depth does not freeze solid. In shallow ponds or containers it helps to move the planting baskets into deeper, frost-free water zones before the first frost. Shoots above the surface often die back in winter; that is normal and no cause for concern. In spring the plant reliably shoots again from the overwintered parts.
Propagation
Methods
- Cuttings
- Division
The easiest way to propagate the common water-starwort is by tip cuttings, which you simply insert into shallow water or moist substrate. After only a few weeks the cuttings form roots of their own and keep growing independently. Larger clumps can also be divided in spring: carefully pull the rosettes apart and plant them separately. Propagation works best from May to August · week 18 to 32, when the water is already warm enough. Make sure the young plants are not immediately overgrown by fast-growing neighbours.
For your garden
Grow Water star yourself
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