Oxygenating plants play an important role in maintaining the health of a pond, their submerged foliage providing food and cover for wildlife and competing with algae for minerals and nutrients, as well as helping oxygenate the water, of course!
Picking oxygenators for your pond is much like selecting any other plant – a question of striking the right balance between personal taste, the overall planting regime, local conditions and the intended purpose. The good news is that there are plenty of suitable candidates, so you shouldn’t have any problems finding something suitable and even the smallest of garden centres usually have more than enough choice to meet most needs.
That said, the range of plants can sometimes be a bit daunting and many of the more unusual or exotic varieties are not sufficiently hardy to cope with a full-on British winter, so as a starting point, here’s our pick of the tried-and-tested best for you to consider.
Other types of pond plants include: Oxygenating pond plants, marginal pond plants, pond edge plants, floating pond plants, floating pond water lilies and deep water pond plants.
Six Of The Best!
1. Hornwort (Ceratophyllum demersum)
A well established favourite, this native plant has branched stems with dense “bottle-brush” whorls of deep green foliage. A hardy perennial, winter care could hardly be easier – the old stems sink in autumn and new ones emerge in the spring. It is a particularly good candidate for deep water and can be propagated in early summer from cuttings or by dividing clumps and since it does not root, its growth is very simple to keep under control.
2. Curly Pondweed (Potamogeton crispus)
Another British native, the curly pondweed makes an interesting-looking addition, varying in shade from green to red/brown and with 4 inch (10cm) wavy-edged leaves which make it look more like a small seaweed than a typical freshwater plant. As an additional bonus, it also produces delicate pink/white flowers above the surface in early summer.
3. Water Milfoil (Myriophyllum spicatum)
Fine feathery foliage adorning long trailing stems make this another attractive candidate for any pond – even the smallest. It can be planted in depths of up to 3ft (90cm) and from May into August it will hold a succession of reddish-green flowers about an inch (25cm) or so above the water. M. spicatum is a native, but other milfoils are sometimes to be seen for sale – though not all of them are hardy, so it pays to check!
4. Water Violet (Hottonia palustris)
As a group, oxygenators don’t tend to go in for much in the way of big floral displays, but this plant is a bit of an exception, producing – as you might expect from the common name – violet flowers on stems up to ten inches (25cm) above the water-level. It is not the easiest pond plant to get established, particularly in hard water areas, but it does well once it is and the mix of bright green, feathery foliage and showy blooms makes it well worth considering for water up to 2ft (60cm) deep.
5. Hair Grass (Eleocharis acicularis)
For shallower water, this plant, also sometimes called Slender Spike Rush, is hard to beat, creating a dense mat-like underwater “lawn” a few inches high. Although it is probably more familiar as a cold water aquarium plant, many pond-keepers have found it an excellent alternative oxygenator for use outdoors. Ideal for depths between 2 and 12 inches (5–30cm) and suitable for small ponds, tubs and water features, it is easy to propagate by splitting clumps in late spring.
6. Water Starwort (Callitriche verna)
Starwort is a great candidate for wildlife ponds, the dense mass of small oval leaves organised in the star-shaped rosettes, which give it its common name, being a haven for all manner of pond-life and particularly aquatic insects. Like the water violet, it can be a little difficult to get going, but its wildlife value makes it definitely one to consider.
Best Of The Rest
There are, of course, plenty of other kinds of oxygenators to choose from, including:
- Willow moss (Fontinalis antipyretica) – a good choice for ponds with spawning fish or wildlife, and tolerates the full range of sun or shady conditions.
- Mare’s tail (Hippuris vulgaris) – more familiar as a marginal, it can be grown in deeper water as a very effective oxygenator (but don’t confuse this with the “horsetail” – a pernicious garden weed! )
- Water buttercup (Ranunculus aquatilis) – suitable for almost any pond, this plant brings plenty of interest, with white buttercup flowers and different foliage above and below the water.
- Goldfish weed (Lagarosiphon major) – also sometimes sold as Elodea crispa, it is a great oxygenator, but although it is less invasive than E. canadensis it will still need to be kept in check.
Although water plants can sometimes be a bit awkward to establish or slow to get going, if you plant a few different varieties, you should soon have a pond to be proud of, but whatever you eventually buy, do remember not to overdo things, however tempting it may be. Those plants will grow soon enough – so no more than five individual plants or bunches per square metre, or you’ll be forever pulling out the excess!