If the garden pond freezes over in winter, the plants used in it are at greatest risk. If you do not want to replace them every spring, it is better to use hardy pond plants that can withstand even the lowest temperatures relatively easily. It is even better if you choose species that actively fight algae in the pond and can largely prevent them - in a completely natural way, because they are in direct competition with them for nutrients.
Hardy pond plants
You know that from the garden: with plants that are hardy, you have significantly less work. They don't have to be brought inside during the cold season and often don't need special protection either. They cope well with cold, ice and snow. Finally, this resilience also saves a lot of money, since they do not have to be renewed every spring. The same applies to pond planting. Here, too, there are varieties that can withstand even the most extreme loads in winter. Even a frozen pond surface doesn't bother them. Basically, you have to distinguish between three variants when planting ponds:
- the bank planting
- plants floating on the surface
- the underwater plants
For all these variants, there are versions that are hardy and cost only slightly more than their more sensitive siblings. However, it is advisable to specifically ask about them in specialist shops and to have their winter resistance confirmed separately.
notice: You should always make sure that all three variants are hardy. It makes little sense, for example, to equip the shore with it, but then to go a different way with the underwater plants.
shore plants
The name already suggests it: riparian plants are planted in the transition area between the land and the pond. They are therefore also directly exposed to the prevailing weather extremes in winter. The following species are considered hardy:
Meadowsweet (Filipendula ulmaria)
Thrives best in semi-shade on rather swampy ground. All meadowsweet varieties are more or less hardy. The real meadowsweet contains salicylic acid, which reduces fever and relieves pain. The flowers are therefore used as an infusion or tea in natural medicine.
Filipendula ulmaria, Meadowsweet
Lady's Mantle (Alchemilla vulgaris)
Perennial plant that loves moist, calcareous and nutrient-rich soil. It should definitely be cut back after flowering in summer. The aim is for the lady's mantle to sprout again before winter sets in. The young shoots then survive ice and snow without any problems.
Marsh cranesbill (Geranium palustre)
It scores particularly well with its violet flowers in summer and prefers moist to swampy soil. In the shore area it is definitely an eye-catcher. The marsh cranesbill is extremely hardy and gets by in winter without any protective measures.
Pennywort (Lysimachia nummularia)
Abundantly growing, typical ground cover that needs moist and, above all, nutrient-rich soil in order to be able to fully develop. Visually, it scores in summer with its many small, yellow flowers, which give every pond bank a very special touch.
Pennywort, Lysimachia nummularia
Meadow knotweed (Polygonum bistorta)
Also belongs to the ground cover and takes up a lot of space very quickly. It enchants with light pink flowers in the months of May and June, creating a very romantic atmosphere. If the winter is particularly cold, however, it is advisable to protect the knotweed with a cover.
tip: If you want to be on the safe side, you should cover riparian plants with fleece or fir branches in winter. These measures are usually completely sufficient.
floating plants
Floating plants swim on the water surface of the pond and usually absorb the nutrients they need directly from the water. This is also one of the reasons why practically all floating plants are also suitable for combating algae. In addition, by covering the surface, they let less light into the pond, which also inhibits algae growth. The following floating plants are hardy:
Three-furrowed duckweed (Lemna trisulca)
Develops a lot of strength by autumn at the latest, which means that the plant becomes heavier and eventually sinks to the bottom of the pond. There she can then overwinter without any problems and, among other things, draw on her strength. In the spring it rises again to the surface.
Frog bite (Hydrocharis morsus-ranae)
Scores particularly well with its circular to heart-shaped leaves and magnificent rosettes. In autumn, the frog bite forms permanent buds, which then fall off and sink to the bottom of the pond. They remain there during the winter months and then sprout again in the spring.
Crab claw (Stratiotes aloides)
Can only be found on the water surface during the flowering period. By autumn at the latest, the plant will sink to the bottom of the pond and develop what are known as sprouts there. The plant overwinters with these sprouts. In the spring, new daughter plants emerge.
Floating Fern (Salvinia natans)
A fern that needs very chalky water to thrive. In the fall, the floating fern dies off completely and sinks to the bottom. The spores contained in the plant then produce new plants in the coming spring.
Dwarf water lily (Nymphaea tetragona)
Typical type of water lily that is available in different colors. The dwarf water lily is definitely a noble visual treat. It is also and especially suitable for ponds that are not particularly deep. With the exception of the yellow-flowered hybrid Nymphaae helvola, it can remain outdoors all year round.
aquatic plants
Practically all native underwater plants are hardy pond plants and usually survive very well if the pond freezes over. However, this does not mean that the plants cannot be damaged. Very severe frost, for example, often causes both leaves and stems to freeze. However, this is usually not a problem because they will simply sprout again in the spring. Typical native aquatic plants are:
- Reed species such as reeds, broad-leaved cattails, windrows or rushes
- Sweet flag, variegated sweet flag, frog spoon and round-leaved frog spoon
- Marsh marigold and iris
- Cyprus grass
Bulrush, calamus, marsh marigold
These are just a few examples of hardy aquatic plants. It is important to make sure when buying that the aquatic plants are actually native to Central Europe. Then you are usually on the safe side. In most cases, aquatic plants native to southern Europe or the tropics do not survive our winters. They would then have to be replaced by new plants in the spring.
Pond plants against algae
As already mentioned, all floating plants significantly inhibit algae growth. There are also a whole range of other aquatic plants that make life and, above all, growth difficult for algae because they rob them of the nutrients they urgently need from the water. These plants include:
- Water Star (Callitriche palustris)
- Tough Hornwort (Ceratophyllum demersum)
- Needlewort (Crassula recurva)
- Thick-leaved waterweed (Egeria densa)
- Spring moss (Fontinalis antipyretica)
- Frogweed (Luronium natans)
- Water knotweed (Persicaria amphibia)
Most of this species are also very good oxygen suppliers. However, not all are hardy pond plants. Here, too, one should therefore limit oneself to the locals.