Brighten up your pond

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We’re paying more attention to our ponds than ever before, so why don’t we make them as colourful as possible?

April through to September (erratic British weather pending) is a time for koi, goldfish, pumps, filters, and setting up or maintaining ponds. But it’s also the key time for pond plants. 

Pond plants have enjoyed a surge in popularity in recent years, largely down to Covid. With many working from home, sales have risen dramatically as more and more people choose to spend money on brightening up their gardens. 

Well maintained foliage is good for ponds and their inhabitants. For one, wildlife benefits from the extra aquatic flora. And note that plants aren’t just an aesthetic addition to your pond but also a functional one. They utilise nitrates from the pond water, using it to feed themselves and denying it to nuisance algae, all while creating a beneficial ecosystem for both fish and wildlife. And, if chosen well, they can bring a startling palette of colours with them.

Different plants serve different roles, and these should be considered to utilise them to their best. Some cover the water, like the leaves of long-stemmed, deeper-dwelling waterlilies, Nymphaea spp., or Floating ferns, Salvinia natans, where the whole plant lives on the surface. Either will provide shelter for pondlife to lurk beneath, as well as creating a barrier to sunlight that could otherwise cause unsightly algae. 

Meanwhile, submerged oxygenating plants may be used a spawning medium, doubling up as protection for the developing eggs and young. 

Know your zones

Plants like to be within their ‘comfort zones’ in ponds — some like to be fully submerged, whereas others may just like to be a little bit soggy. Kept in the wrong zones they may even die, so it is important to know the placement for each. Most plants come with labels that tell you which area to place them, but failing that an experienced retailer can point you in the right direction. 

There are five zones to be aware of. In zone 1 you’ll find those plants which like to be a little wet, that sit outside of the pond but are kept moist — think bog garden plants like Primula. These are often used to soften the edges of the pond, making it blend seamlessly into your garden. Bog garden plants love the nutrients that can be found in regular garden soil, but when kept too wet they can suffer with root rot and fungal diseases.

Zone 2, somewhere between 0-15cm deep, is where plants start to dip into the water properly, and is suitable for most marginal plants as well as some potted oxygenators. Marginals usually sit on a little shelf at the edge of the pond, but if no shelves are available then an upturned plant pot will do just as well. Put these plants in the water so the pots are only just submerged, but don’t let them drop lower than 5cm below the water’s surface. 

Zone 3 is deeper, from 15cm to around 40-45cm, and is best suited for deep-water marginal plants. Tall, grassy types of marginals like Lesser bulrush, Typha angustifolia, as well as potted oxygenators like Water crowfoot, Ranunculus aquatilis, all do well here.

Zone 4 is the bottom of the pond, and home to the quintessential waterlilies and other deep-water species such as Water hawthorn, Aponogeton distachyos. These plants will spend their life at the bottom of the pond around 50-100cm depth. If lilies are placed in an area that’s too shallow, they will die. Adversely, if they are too deep then they will fail to flower.

Finally, zone 5 is the open water, for those plants that float on the surface. These are some of the easiest to keep as they don’t need to be potted or contained.

With that covered, let’s now take a look at some of the more colourful plants you can use to spruce up your pond…

Marsh marigold, Caltha palustris

The Mash marigold is an all-time favourite. A native British plant, its striking buttercup yellow flowers and hardy nature make it perfect for that initial pop of colour early on in the season. 

It grows to around 60cm into a beautiful dome of upright stems and will come back every year. If it’s cut back after its initial flowering it will then flower yet again in late autumn.

 As the name suggests it’s suited to zone 1 bog gardens, but it’s so versatile that it will also happily take to zone 2 — pop it on a shallow shelf and watch it grow. The nectar from its yellow foliage caters to insects that appear early on in the year and it also provides much-needed cover for frogs. A truly well-rounded plant.

Water mint, Mentha aquatica

As the name suggests, Water mint produces a gorgeous aroma of mint when the wind blows or the leaves are brushed against. Producing delicate round clusters of mauve-coloured flowers in the summer and reaching a height of 30cm, its nectar-rich flowers attract a number of pollinators such as butterflies and bees, making it functional and aesthetic. For best growth keep it in zone 1 or 2, but note that allowing this plant to dry out will leave it susceptible to rot. Try to keep it in a part of the pond where it receives full sun, or dappled shade at most, and it will thrive.

Scarlet lobelia, Lobelia cardinalis spp.

‘Queen Victoria’ Lobelia cardinalis produces a mass of striking scarlet flowers through summer on tall, deep maroon stems growing to 90cm in height — this is truly one of the more colourful marginal plants out there. The contrast of the red against the greens of other flora makes it a perfect choice for those wanting something different. Because of its height I would suggest you tie it to a supporting cane to maintain its structure, or it may become a little unruly or end up breaking clean in half. This is another versatile plant that can be in the moist conditions of zone 1 and into a zone 2 position of the pond itself. A beautiful magnet for butterflies and insects, just remember to cut back any dying foliage in autumn.

Creeping jenny, Lysimachia nummularia

A hardy British native plant with an abundance of yellow flowers in summer on low trailing green leaves. It reaches around 45cm in length, and is great to blur the edges of the pond in either zone 1 or zone 2. In the latter, the leaves can raft across the surface of the pond providing cover for creatures beneath. You can also find a ‘gold’ version available where the leaves are paler and golden coloured for that extra contrast.

Barred Horsetail, Equisetum japonicum

Tall and fleshy evergreen stems with black bars around them give this plant its common name, and although this species will not produce a flower, it is coveted for its markings alone. It grows tall, eventually to over 80cm, and is particularly valued for adding interest in winter as it keeps its attractive green foliage. The Barred horsetail can take its place anywhere from zones 1 through to 3, though at the deepest end the water should not be more than 15cm above the pot. As a marginal plant its reed-like structure can act as protection for small fish and visiting frogs and newts. The spread of this plant can be quite vigorous, so if you are planting in zone 1 you might want to consider keeping it confined to a container to restrict its growth and stop it spilling out into other areas of your garden.

Water liles, Nymphaea spp.

A pond plant list isn’t complete without the water lilies. Ask someone to think of a pond plant and their immediate go-to will usually be one of these hardy flora – and with good reason. They come in a range of colours from red to pink, white to yellow, and even copper. Large lilies (Alba, Marliacaea Carnea and Gladstonia) may spread over 2m square of a pond’s surface, while smaller versions called pygmy lilies (Pygmaea helvolva, Pygmaea rubra) are available, and these will only cover an area around 50cm. Although lilies are generally hardy, they can be a little fussy. These are all true zone 4 plants, and most comfortable under the surface of the water at a depth between 50-100cm. The use of upturned plant baskets to raise up the lily is especially useful when first introducing it to your pond — you want to lower it in stages, avoiding plunging it too deep at the start.

It’s important to keep lilies away from running water, including waterfalls, filter returns and fountains as they prefer still water. If your pond is in full sun the lilies will thrive, but it’s always worth feeding them, either with a fertiliser stick that you push into the pots, or a liquid pond feed, as they are vigorous and hungry plants. In terms of flowering, they do this from June through September if kept in optimal conditions. Each flower lasts around four days, opening and closing daily. Do not be disheartened if it does not flower in the first year, it is just getting used to its surroundings. Patience is a virtue with all pond plants, especially so with lilies.