Choosing Aquatic Plants for your Greenseal Liner

Choosing Pond Plants

Pond plants will oxygenate the water and keep it clear. Unfortunately many non-native aquatic plants readily obtainable from garden centres are invasive and will soon dominate the pond completely to the detriment of everything else.Carefully selected native species should remain in a relatively balanced state and will support more wildlife. Plants can be introduced to your pond approx. 1-2 weeks after the initial filling with water,when tap water nutrients such as chlorine and fluoride have evaporated. The best time to plant is in spring or summer when plants are actively growing. Plants can be planted into soil held in old string onion bags or baskets.

Four zones for plants

There are four ‘zones’ in which pond plants may be grown; try to have plants in each zone. The four zones are:

1. Totally submerged (in deeper water)- oxygenating plants

2. Submerged but with floating leaves (also in deep water) - oxygenating plants

3. Emergent (in shallower area) and

4. Marginal (growing in the pond edge and bog areas.)

A useful rule of thumb is to provide one oxygenating plant per 100cm2 of open water.

The taller, marginal/emergent zone plants are better on the northern edge where they won’t cast shade over the rest of the pond. In the wild, the four zones are not really distinct at all but merge into each other. Some marginal and emergent plants therefore are interchangeable.

Plants suitable for each zone, and plants to avoid,are listed below:

Pond plant lists

Recommended Plants:

Submerged oxygenators

Spike Water Milfoil Myriophyllum spicatum

Hornwort Ceratophyllym demersum (pollution intolerant)

Shining Pondweed Potamogeton lucens

Horned Pondweed Zannichellia palustris

Fennel Pondweed Potamogeton pectinatus (pollution tolerant)

Water Starwort Callitriche stagnalis (pollution intolerant)

Floating-leaved

Water Crowfoot/Buttercup Ranunculus aquatilis (pollution intolerant)

Bladderwort Urticularia spp

Frogbit Hydrocharis morsus-ranae

Broad-leaved Pondweed Potamoeton natans (pollution tolerant)

Curled Pondweed Potamogeton crispus (pollution tolerant)

Emergent

Branched Bur-reed Sparganium erectum (tall; can be invasive, but a good alternative to Typha)

Amphibious Bistort Persicaria amphibium

Arrowhead Sagittaria aquatilis

Water Crowfoot Ranunculus aquatilis

Water mint Mentha aquatica (can be invasive: also strong scent deters some insects)

Flowering Rush Butomus umbellatus

Water Plantain Alisma plantago-quuatica (tall)

Water Forget-me-not Myosotis Scorpiodes

Stinking Iris Iris foetidissima (tallish)

Marsh Cinquefoil Potentilla palustris

Swamped grasses - good for pond invertebrates

Yellow flag Iris Pseudacorus (can be a little invasive)

Marginals

Flowering Rush Butomus umbellatus

Lady’s Smock Cardamine pratensis

Marsh marigold Caltha palustris

Purple Loosestrife Lythrum salicaria (tall; a wonderful bee plant)

Gipsywort Lycopus europaeus

Sedges large and small

Meadowsweet Filipendula ulmaria (tallish; good for birds in autumn)

Brooklime Veronica beccabunga

Ragged Robin Lychnis flos-cuculi

Soft Rush Juncus effusus

Water Forget-me-not Myosotis scorpioides

Bungle Ajuga reptans

Water Avens Geium rivale (spreading)

Marsh Woundwort Stachys palustris (tall)

Great Willowherb Epilobium hirsutum (tall)

Hemp Agrimony Eupatorium cannabinum (tall)

Fleabane Pulicaria dysenterica

Rough grassland with Creeping Bent Agrostis stolonifera,

Marsh foxtail Alopecurus geniculatus.

Fool’s watercress Apium nodiflorum

Common Spike-rush Eleocharis palustris

Water pepper Persicaria hydropiper

Silverweed Potentilla anserina

Creeping Jenny Lysimachia nummularia (low growing ground cover)

Water Dock Rumex hydrolapathum (may be invasive)

Plants to AVOID at all costs:

1. Australian Swamp Stonecrop/New Zealand Pygmyweed Crassula helmsii akaTillaea recurva

2. Water Fern Azolla Filiculoides

3. Parrot’s feather/Brazilian watermilfoil Myriophyllum aquaticum

4. Floating Pennywort Hydrocotyle ranunculoides

5. Himalayan Balsam Impatiens glandulifera

6. Canadian Pondweed Elodea canadensis

7. Curly (Canadian) Pondweed Lagarosiphon major or Elodea crispus

8. Nuttal’s pondweed Elodeanutalli

Native plants that tend to become invasive;

only recommended for larger ponds:

1. Floating sweet-grass Glyceria fluitans

2. Reedmaces Typha latifolia and Typha angustifolia

3. White water lily Nymphaea alba (pollution tolerant);usually prefers deep water 2m deep (could be grown in submerged pots)

4. Yellow water lily Nuphar lutea (pollution tolerant) (could be grown in submerged pots)

5. Fringed Water lily Nymphoides peltata (could be grown in submerged pots)

6. Lesser and Greater Spearworts Ranunculus lingua and R. flammula (could be grown in submerged pots)

7. Bogbean Menyanthes trifoliata

Pond open for business: attracting wildlife

A wildlife pond may take over 5 years to become fully established. Certain animals can be encouraged to visit by providing particular features:

A patch of unmown long grass, logs and stones bordering the pond - for froglets, newts also butterflies.

Floating leaved plants - for dragonflies and damselflies to lay their eggs upon.

Logs and stones on a sunny open bank - that some dragonflies like to perch upon.

Tall emergent plants with hollow stems - for damselflies and dragonflies to lay their eggs upon.

These insects may take 3 years to mature, so need a relatively stable habitat with lots of other pond creatures to eat.

Damp bare earth - which house martins and other birds will use to help build their nests.

The plant Water Starwort - seems to be favoured by newts for egg laying.

Shallow areas - for birds to bathe in; the sound of dripping water attracts some warblers.

A nearby compost heap - may be used by grass snakes to lay their eggs in if you are lucky.

Night-scented plants like honeysuckle and the provision of batboxes - may attract bats.

A beach or chicken wire hedgehog ramp - so thirsty hedgehogs can have a drink (or a swim) without getting trapped.

Meadowsweet - will be perched upon and the seedheads eaten by finches later in the year.

Duckweed - attracts frogs by smell early in the year.

Important a wildlife pond should NOT have any fish, nor pumps, filters or fountains.

Fish will eat all the other wildlife; pumps will suck in and destroy all the smaller creatures that other wildlife depends upon for food.

Maintaining your pond for wildlife

General rules

1. Avoid chemical treatments at all times.

2. Be careful when digging or raking near or in the pond - an impetuous spade can puncture a rubber liner very easily; if using a rake, make sure the tines are pointing upwards!

3. Avoid disrupting the pond in spring and summer; try to carry out maintenance work in autumn and winter instead.

4. When introducing pond plants, native species are usually of more benefit to wildlife than exotics. For the wildlife pond purist, pond plants could be native not just to the UK but also specifically to Northumberland.

The secret to looking after a wildlife pond is to maintain a stable balance of plants and creatures, similar to what would be found in the wild. This can be achieved by ensuring that sufficient plants are present in each of the four depth zones and that there is a healthy population of pond creatures - both predators and prey. Tiny animals like Daphnia, the waterflea will graze on plants and algae and be a source of food for all the other ponds inhabitants such as dragonflies, beetles, nymphs, frogs and newts. This is why it is important not have fish or motorised pumps and filters in a wildlife pond - these will effectively remove whole sections of the pond ecology and make it very difficult to achieve a natural balance.

Practical maintenance of a wildlife pond

If the pond can be kept in this relatively balanced ecological state, it shouldn’t need very much maintenance at all. Problems don’t usually start until the pond is over 5 - 6 years old. The main things to watch for are:

Build up of dead organic matter such as fallen leaves and dead vegetation at the bottom of the pond. The water turns brown as all available oxygen is used up by the decay process.

Some dead organic matter is useful however as a substrate for other plants. Eventually, a layer of silt accumulates which makes the pond shallower. Again this silt layer can be a useful feature - for overwintering minibeasts and hibernating frogs. Providing there are no other problems, de-silting can be carried out approximately once every 5 years. The best time is in autumn before wildlife and minibeasts go into hibernation and after plants have finished flowering. Leave dredging on the edge of the pond for a few days so that minibeasts can escape back into the pond.

Encroaching vegetation. After a while, some pond plants may be growing too abundantly; these can be pulled out or divided once every year or once every two years, reducing their presence by about one fifth to one third/one half. Once again, this should be done in the autumn before minibeasts go into hibernation. Some plants can be grown in pots, which limits their spreading. Aim to make sure that at least 10%, but less than 30% of the pond surface is open for 60% of the plants present. Once again leave vegetation on the banks of the pond for a few days so that minibeasts can escape back to the pond.

Winter and summer. It is important that the pond does not become completely frozen solid in the winter. Ponds deeper than approximately 60cm do not usually become frozen right to the very bottom and should be safe. However, it is still necessary to provide some open water so that oxygen can diffuse into the pond. An easy way is to float a ball on the pond that can be removed, leaving a hole in the ice.Or rest a hot pan on the surface (remove before the ice melts completely!) Using hammers and boiling water is not recommended, as this sets up shock waves or boils wildlife.

In summer the pond may need to be topped up in hot weather. Tap water is the most convenient source, but the high level of nutrients such as fluoride and chlorine may induce algal blooms, whereby the water turns a vivid green pea soup colour. This should fade after a few days as the pond recovers its balance. Rainwater is preferable if you have a water butt. It is better to refill little and often rather than in one go. If you have an adjacent bog area, this may also need to be watered in summer.

Caring for creatures. Make sure there are sufficient areas of habitat such as logs, stones and rough vegetation at the pond edge, especially during winter when these will be used as hibernation sites by frogs, newts and others.

A note about bog habitat areas. In the wild, bogs are usually kept damp not only by inhibiting drainage from above but also by drawing up water from underneath. This is very unlikely to happen in the garden,which means that over time the bog may become progressively more acidic. One way to counter this is to bury a perforated hose under bog area. This can then by connected to a water supply so that the bog canbe watered from below.

Above article is published with the kind permission of Nothumberland Wildlife Trust.

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