Oxygenating Pond Plants

Good choices include submerged species such as hornwort, water starwort, water violet, water crowfoot and suitable pondweeds. The best choice depends on the pond's depth, size and conditions, so using more than one suitable species can provide useful underwater habitat as well as plant diversity.

As a general guide, the RHS suggests around four to five bunches of submerged oxygenators, each containing three to four stems, per square metre of water surface. Avoid excessive planting, as submerged plants also respire at night and overcrowding can cause problems.

Oxygenating plants can contribute to a balanced pond and compete for nutrients that might otherwise support excessive algae growth. However, they are not a guaranteed cure for green water, as water clarity is affected by factors including sunlight, nutrients, plant coverage and the overall balance of the pond.

It depends on the species. Some submerged oxygenators are rooted and can be planted or anchored in aquatic baskets, while others can grow freely in the water. Follow the planting instructions for the individual species rather than treating all oxygenators in the same way.

A pump can circulate and aerate water, but oxygenating plants provide additional benefits such as underwater cover and habitat for pond life. For a wildlife pond, plants are therefore useful for more than simply adding oxygen to the water.

The best wildlife pond plants provide a mixture of underwater cover, surface shade, flowering habitat and places for aquatic insects to emerge. A balanced pond can include oxygenating plants, marginal plants and floating-leaved plants such as water lilies. Native species are particularly useful for supporting UK pond wildlife.