Last updated: Saturday, 29 July, 2006 3:19 PM

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A

AQUIFERS (fountains)
AUTUMN POND CARE

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An Autumn pond looking rough and overgrown. What to do?

Autumn is an excellent time to deal with a neglected pond. Remove all debris from the water and thin out oxygenators from the bottom of the pond — remembering to place them at the side of the pool for a few days to allow any aquatic animals to return to the water.

Dead or diseased foliage should be trimmed back from water lilies and marginal plants, especially where the vegetation is likely to fall into the water. If you want to lift and divide overgrown marginal plants, this can also be done now. Finally, fallen leaves must be kept out of the pool to prevent them rotting and fouling the water, so place a fine mesh net over the surface, or scoop out any foliage every few days.

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B

Blanket weed or filamentous algae –whatever you call it (photo) – is a woolly, green menace, which invades ponds, especially at this time of year (May/June). It does little harm to pond life but looks awful.

Blanket weed needs three things to thrive: light, nutrients (from tap water, rotting leaves and fish faeces) and little competition for the first two from higher plants. It often comes in when you establish a new pond with tap water or when an established pond gets too much sun early in the season and last year’s organic matter is left to build up in the water. It’s good to have plenty of surface cover plants, such as water lilies, to take care of the light problem.

As for the nutrient problem, make sure you’ve plenty of underwater plants, some which shade the surface. Keep stripping bits out to keep it tidy and to deliberately impoverish the level of nutrients in the water. Duckweed and underwater oxygenators such as hornwort are ideal. Do it regularly and put the unwanted stuff on the compost heap too.

If none of these solutions work, the only option is to start again around late July or August when the least disturbance is caused to amphibian life.

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D

DUCKWEED

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What can I do to remove duckweed from my small garden pond?

Lemnaceae, or as it's more commonly known, duckweed, is a tiny green plant that floats underneath or on the surface of water. It has small, green shoe-shaped leaves, which absorb sunlight, and grows mainly in fresh water, except for 'fat' duckweed, found in slightly salty water. It creates a blanket-like effect and once it is in your pond, it is almost impossible to eradicate. But duckweed does have benefits, including oxygenating the water and providing food and cover for fish. There are several ways to control it. The first is to remove as much as you can using a fishing net, disposing of it carefully so it does not contaminate other wet areas. Alternatively, you can buy some grass carp, which relish duckweed, but you'll need quite a few to keep it in check. As your pond is not very big, you could empty it and wash away the duckweed. But be thorough: if you leave any traces, it will soon multiply and you will be faced with the same problem again.

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F

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Juncus ensifoliusFlying Hedgehogs’

This dwarf rush thrives in damp conditions, so it’s perfect for fringing around the edge of a pond. The seed heads look like little brown pompoms wavering over the dark green foliage and to it at its absolute best plant it en masse. It grow to a height of 25cm. Buy it directly from Mr Fothergill’s online at www.fothergills.co.uk or tel. – 0845 166 2522. Mr Fothergill’s seeds are also available at selected garden centres. £1.99 for 25 seeds. (Dec. 2005).

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Which floating plants should be used in a garden pool?

Floating plants will survive in deep or shallow water, and are very low-maintenance. The easiest one to grow is water soldier (Stratiotes aloides), which has rosettes of sword-shaped leaves and white summer flowers, as it is hardy and can be left in the pool all year round.

Other floating plants that are often used include fairy moss (Azolla filiculoides), which has small fern-like leaves that turn red in summer; water chestnut (Trapa natans) for its dark, serrated foliage; and water hyacinth (Eichhornia crassipes), with its beautiful violet flowers. These are vulnerable to frost and should be overwintered indoors between October and May in plastic containers filled with pond water.

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Should the surface of a pond be left frozen over during the winter?

It is a good idea to prevent the pond surface freezing for long periods. Freezing stops an exchange of gases between the water and the outside atmosphere, so that toxic gases (caused by decaying organic matter) can build up, either harming or killing fish and other wildlife.

There are several ways to stop this but the simplest is to install a low-voltage pool heater. Or you can create an air hole to let gases escape by placing a warm kettle on one corner of the pond (away from dormant plants) to melt the ice, although on cold days this can soon freeze over again. Under no circumstances should thick ice be smashed, as shock waves will be released to the detriment of fish

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P

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Do I need to cover my medium-sized garden pond during the autumn?

If any deciduous trees and shrubs are near the pond, it is important to cover the surface throughout the autumn, as this will stop falling leaves polluting the water to the detriment of fish and other wildlife.

The best material to use as a cover is a sturdy sheet of fine plastic mesh; this should be positioned a few inches above the water surface and secured around the edges with tent pegs or bricks. Check the mesh regularly and always remove any foliage that accumulates on top, otherwise the combined weight may damage it. If any leaves do manage to get underneath the cover, use a fishing net to scoop them out.

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Pools of calm

Forget plumbing, pumps and paraphernalia - still waters bring drama and lyricism to even the smallest space

Still water has a way of making gardeners run deep, and nowhere is this more evident than in the new generation of water features. Limpid and intimate, many of these pools, tanks and tubs are no more than a metre square. Most are liberated from the lawn, and instead promoted to starring roles on terraces, rooftops and balconies (weight permitting), made centrepieces of borders and parterres, or set deep among trees and shrubs. They might be serenely empty or stocked with plants and fish; rigidly formal or artlessly rustic; sunken or raised; purpose-designed or craftily improvised. They have little in common, apart from their size, their stillness and their gift to the garden of drama and lyricism.

But there are some things that they are not. They bear no resemblance, for instance, to the variety of horrors spawned by TV garden makeover shows, from pre-plumbed, high-voltage crystal grottoes to die-cast rockpools that look as if they have been filched from the Thunderbirds set. Nor are they reminiscent of the old world of aquacultural DIY, with all its nightmarish technicalities. The new water feature is small and still, smart and simple, a delight for even the most confirmed horti-hydrophobics.

I was forced to take the plunge myself recently when my partner took the extraordinary step of buying some koi. Extraordinary because she had forgotten – or chosen to ignore – the fact that our garden lies on a bed of concrete and is barely large enough to accommodate a bird bath. With a clutch of carp to house and no way of digging down or moving outwards, I had no choice but to create a small, freestanding pond – a water feature – and fast. In its infancy, it resembled a cramped and primitive spa bath: a raised bed, basically girt with bamboo, filled with soil and with a pre-cast pool in the centre. The koi were happy; I, less so. Then the gardening began and prospects brightened.

It became possible to grow a small water lily such as Nymphaea ‘Pygmaea Helvola’ and to have it close enough to smell its chrome-yellow flowers. For high summer camp, we might plunge a pot of the white calla lily Zantedeschia aethiopica, or a peach and flame-flowered water canna such as C. x ehemanii, or cast adrift a lilac, orchid-like water hyacinth (Eichhornia crassipes). In autumn, I could watch the curious seasonal diving habits of the water soldier (Stratiotes aloides), a native plant that resembles an aquatic bromeliad and that sinks to the bottom of the pond in winter to resurface for summer. For the margins, there were the rush Schoenoplectus lacustris ‘Zebrinus’ with
ivory-banded quills, and the lime-and-gold sedge Carex elata ‘Aurea’. For tumbling over the edges, we used cushions of golden mind-your-own-business (Soleirolia soleirolii ‘Aurea’) and a finesse of ferns.

There is, of course, no need for quite this degree of abundance, and you can forget all the grief of construction, too – a micro-pond, for a terrace or balcony, say, can be made using a large ceramic pot: just smother its base with aquarium sealant to block any holes. Nor is naturalism, asymmetry or chaos de rigueur. In fact, the saving of the small still-water feature has been its move into the realms of minimalism and formality. A raised boxed pond in wood, steel or slate, or a sunken, sharp-edged rectangular rill, will look breathtaking in summer with a few pots of the white calla lily below its surface.

All plants can be found at most good garden centres. Specialists include Bennetts Water Gardens, Weymouth (01305 785150; www. waterlily.co.uk); Dorset Water Lily Co, Yeovil (01935 891668; www.dorsetwaterlily.co.uk); Paul Bromfield Aquatics, Hitchin (01462 457399; www.bromfieldaquatics.co.uk); Stapeley Water Gardens, Nantwich (01270 623868; www.stapeleywg.com)

DESIGN NOTEBOOK

Size and container

Aquatic plants can be grown year-round  in water-filled pots or tanks. For submerged plants such as the water lily Nymphaea ‘Pygmaea Helvola’ (above), a water depth of at least 30cm over the crown of the plant is required. For more elaborate pools housing a variety of plants and even a few fish, a minimum volume of 160 litres is needed with a depth of at least 60cm. Any kind of impermeable container will do, but siting matters: if it is to support life, the pool must not overheat or freeze for long periods.

Plants and pots

In a small pool, you are unlikely to be able to create shelves for plants requiring different water depths. Instead, plant them in water-lily baskets or clay pots and submerge the pots to the required levels, standing them on bricks if necessary. Several plants of the same group (say, three marginals such as a rush, a sedge and a water lobelia) can be planted together in one basket to make a miniature bed. 

Use a soil-based compost that is low in feed (water-lily compost is ideal); top-dress the containers with gravel, and ensure that the pot is below the water. Tender aquatics such as canna, Thalia and (in cold areas) Zantedeschia can be removed in winter and kept moist and in bright, frost-free conditions until the spring.

Water quality

To avoid stagnation and compensate for evaporation, replenish the water by about a third every fortnight between late spring and autumn; simply run a hose into the pool or pot and allow the water to run over. Algal bloom is inevitable where soil and light combine with water; but it usually decreases with time and as other plants begin to thrive. In a small space, its worst manifestation (blanket weed) is easily removed. Adding a non-toxic black dye to the water can also mask a greenish bloom.

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Struggling to keep a pond clean? Bulrushes taking over? How to prevent this.

Ponds are prone to free-floating algae (the green stuff), which thrive in sunlight where there are high levels of mineral salt in the water. To control that, you need oxygenating plants to absorb the salts and cast shade on the water. Some of these can be invasive, such as Myriophyllum aquaticum (parrot feather), Myriophyllum verticillatum (water milfoil) and Lagarosiphon major (goldfish weed), so avoid them. You are better off with plants such as Eichhornia crassipes (water hyacinth), which floats on the water and produces orchid-like flowers; Pistia stratiotes, or water lettuce (store indoors in a container of water during the cold season); and water lilies (Nymphaea).

Once you've got algae, however, it needs to be removed, and this can be done in several ways: 1) Use a stick or rake and simply twirl it like candyfloss (leave the algae on the bank, to give wildlife caught in them the chance to escape); 2) Barley straw placed in water is said to destroy algae. You can buy this in ready-to-use pads; 3) There are numerous chemicals for pond clearing, but read the instructions carefully or you may lose more than algae.

Now to those dreaded bulrushes. Typha angustifolia (or latifolia) is a deciduous perennial that grows to over 2m. Controlling it is a problem, so think about alternatives such as Acorus calamus 'Variegatus' (sweet flag), which is tangerine-scented with variegated leaves that turn pink in spring. To get rid of the rushes, I think it's best to wade into the pond and pull up the plants (do not leave any roots in the soil). You can use Round-Up (or any other weedkiller containing glyphosate), though this will kill all other greenery with which it comes into contact. In general, I don't recommend chemicals for pond cleaning, because they don't do wildlife any good. If the pond has a polythene liner, take out all plants and animal life before any sort of cleaning. And remember: using chemicals can cause more algae to be produced.

 

ALSO

 

Lettuce Luck
So many articles appear relating to the dreaded blanket weed that I felt I should share my experiences. After years of keeping aquarium fish, I was a little nervous of starting such a large project as my new pond. I was especially worried about green water and blanket weed due to the pond being in full sun. Therefore, I installed a UV to tackle suspended algae and an electronic blanket weed controller.

However, I believe that the luckiest find was the water lettuce (Pistia stratoites)! We were keen to achieve a fully planted pond and wanted some floating plants too. So we bought some water hyacinths and water lettuce. The water lettuce multiplies at an unbelievable rate which you then ‘harvest’.

After a little research on the web, I found that in some countries there are real environmental problems with water lettuce clogging up rivers and lakes so badly that boats are unable to travel through! However, for our pond this was ideal as the water lettuce a healthy competitor for the blanket weed by removing nitrates from the pond.

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A pond covered with duckweed that chokes the water lilies. What can be done?

High nitrate and phosphate levels encourage duckweed (Lemna). To reduce these, pull up the Lemna , then encourage a more varied planting scheme, including submerged (for example, Elodea crispa ) and marginal plants (for example, Calla palustris) as well as floating ones (such as lilies or water hyacinths). Plant leaves should cover a third to half of the pond's surface. A long-term solution is to put in submerged oxygenating plants and algae-consuming fish. Avoid ducks: they destroy plants. For information, call The Ponds Conservation Trust, 01865 483249.

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September is the time to repot overgrown marginal plants, so they can establish before winter. Perforated baskets are perfect for small fish ponds, but if you keep koi you will need to use a solid sided container and to cover the surface with heavy stones to prevent the plants being uprooted. (Planting up a marginal basket).

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1.

Do you need to put oxygenating plants in a pool?

Oxygenating plants are aquatic species that live in the bottom of ponds. They are vital to the health of the pool and, as the underwater leaves grow, they absorb carbon dioxide and excess minerals — this deprives algae of nutrients and helps to limit their spread and ensure the water stays clean. The production of oxygen is less important, despite their common name. Oxygenators also provide a home for pond creatures and fish.

When planting — May or June are the best months — fill a 6in perforated plastic container with aquatic soil to 1in below the rim and firm the rootballs into the earth. You will need three bunches of oxygenators per pot and one bunch for every two square feet of surface water. Before placing in the pool, spread gravel over the soil surface to prevent the plants from being washed out.

 

2.

August

A pond has become overgrown and is now choked with oxygenating plants. Is it possible to remove these now or should it wait until winter?

Now is an excellent time for lifting and dividing oxygenating plants. This allows the growing oxygenators to settle and re-grow a little before the onset of winter.

Be as gentle as possible so that you do not excessively disturb the pond. It is important to leave enough oxygenators to do their job. Also, leave enough to give the fish somewhere to hide.

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Watch your step (February)
Ponds and streams — such calm places. Time to add a little drama, says Stephen Anderton

One of the great things about water in a garden is the risk, the danger. Of course, water can be calming, and it’s good for wildlife, and it’s pleasant to hear it tinkle and splosh. But crossing a stream or pond — physically coming to terms with the water below — is when it can become exciting.

Riskiest and most rewarding are stepping stones. You can take raised blocks of stone across a stream and have water swirling beneath your feet. You can take a path straight across a formal pond by making low stepping stones, raised barely above the surface of the water and set far enough apart to require careful negotiation rather than easy marching.

Bridges, by comparison, are a much more civilised game, but even these offer varying degrees of excitement. To add a little drama, for example, you can raise a bridge higher over the water by putting steps at either end, or you can take a gulley of water under a set of rising wooden steps.

Maybe the real difference between a bridge and stepping stones is that stepping stones are meant to get you across as quickly as possible, but a bridge is safe enough to enjoy stopping and looking at the water below. It is a place for lingering and should be designed that way.

People admire arched bridges for their reflection and conspicuous strength. But an arch also encourages you to stop and look down at the water; watch the fish, maybe, or admire your water lilies, before descending the other side.

Where you have enough water to play with, it is fun to make a devil’s bridge which changes direction halfway across (the Devil notionally has to cross water in straight lines). You might make a platform at the bend — somewhere to sit and place your feet in the water. You might even make a little gazebo there, with chairs and candlelight.

Some bridges cross streams not at right angles but on a longer diagonal. The result can be charming, especially when the path approaches the stream at the same oblique angle, slicing across both garden and water.

A bridge with a simple rail or balustrade is almost always more enticing than one without. It suggests that there is plenty of water there (to fall into, that is), and is another chance to make shapes for reflection. It also offers somewhere to stop and lean, so it is worth adding a rail to almost any bridge more substantial than a plank crossing. You can elaborate railed bridges to become aerial pergolas draped with climbers planted on the banks. You can make bridges with rails splaying on to the land like funnels, sucking you into the narrows of the bridge itself. I know one garden bridge where the first board is sprung so that, as you step on to it, tiny Indonesian bells chatter along its rails.

It is a bigger challenge to make the crossing over a small, simple watercourse interesting. One way would be to design an arrangement of wooden sleepers that extends for a few feet across the bog-garden banks of the stream to form a raised walkway as well as a bridge. The narrowness would create a sense of negotiating a rope bridge across a gorge and would also draw your eye down to the planting. Alternatively, place a single stepping stone in the stream, between grassy banks. Or set a large paving stone in the water, as if it were a piece of path shrunk a few inches away from the bank. If the path either side is paved in the same material, so much the better. The stone is supported by invisible piers, so the water seems to flow freely underneath and the path to float. Isn’t this the best of all worlds — a comfortable path which, apparently, could be washed away at any moment?

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February 01, 2004

 

Reflections on pond life


Adding a pond to your garden will bring a calming presence and encourage the local wildlife. It needn’t be expensive either, advises Joe Swift, but regular maintenance is essential

A pond is a great way to introduce the calming element of water into the garden and appeal to the local wildlife. If you stick to a simple design without moving water (which would necessitate a pump) and are prepared to engage in some DIY, you should be able to install one from about £150.

If you have a formal town garden, then the pond should be similarly formal, using a strong geometric shape such as a square, rectangle or circle. These shapes are also the easiest to execute successfully. Think about whether you want it sunken or raised — what will you see in the reflection in both cases? The advantage of a raised pond is that you can build the edges at a perfect seating height, as it is always tempting to sit close to water, and there is less spoil to deal with from the digging process because you will not be digging so deep.

Although there have been many advances in durable and flexible pond materials and reliable pumps, there is no denying that ambitious water projects are the most problematic of all landscaping jobs and need careful consideration. Remember that water is extremely heavy (one tonne per cubic metre) and there is little room for error. If you are not a dab hand at construction work, it may be worth calling in a professional. Your local garden centre may be able to help or you could contact the Society of Garden Designers to find suitably qualified designers.

It is important that the pond is maintained properly. If not, it will deteriorate and detract from the garden as a whole by looking messy — and probably smelling, too. So think about maintenance before installing one. Who will look after it and how long will this take? At particular times of the year (when cleaning it out in autumn, for instance), a pond can be time-consuming. These questions will help to decide the scale and type of the water feature you choose.

There are various ways of installing a pond. Butyl has a 25-year lifespan and is the most flexible and reliable way to line a pond. It can be bought on a roll and neatly folded for awkward shapes, or you can get it “box welded” by the supplier with proper corners, so that it can be easily slipped into a pre-dug geometric shape. Another advantage of Butyl is that you can build on top of it with concrete or cement to create stepping stones or waterfalls, without fear of tearing.

Ponds should be at least 2ft deep for fish and plants, so that when the water freezes, there is room for them to survive under the ice. Put at least 2in of soft sand or some pond underlay beneath the liner to stop any sharp stones from puncturing it. Slowly fill the pond with water, so you stretch the liner evenly (preferably on a warm day, as this makes it more malleable) to create smooth sides.

Concrete ponds with a waterproof render can also work successfully, but it is worth placing a liner of some sort underneath as eventually all concrete ponds crack. Prefabricated fibreglass liners are available in a variety of shapes from aquatic garden centres. They can be the simplest and cheapest way to install a pond, but over time they will usually become brittle and possibly crack.

There is nothing worse than seeing a lot of liner around the top edge of a pond. Think about the edge of the pool and how you are going to integrate it with surrounding materials, as well as how to disguise the liner. Evaporation in the summer will lead to a drop in the water level, so make sure the construction allows for the inner edge to be visible without showing any liner. This can be done by laying a course or two of stone or engineering bricks below water level and on the inside face of the liner. If you have young children, consider installing a grille just under the surface of the water as a safety measure.

You could create a “soft” edge with plenty of planting. A shallow sloping pebble beach leading through the planting into the water looks good. Or create a shelf around the edge, 6in to 8in below water level, on which to stand marginal plants. I generally put this shelf on the edge furthest from the house so the pond and its reflections aren’t obscured, but the far edge of the liner is.

The balance of plants is essential in a pond to ensure good water quality — dirty or cloudy water is not going to look attractive whatever style of garden you have. If there is no filtration system or regularly moving water to help oxygenation, it is important to plant the pond well. When the sun hits the surface of the water in spring it will encourage algae to grow, which turns the water green. All ponds go a bit green in the spring, but if they are healthy they will quickly clear up. Covering the surface with plants will keep the sunlight off the water and help keep it clear.

Ideally, at least 50% of the water surface should be covered and this will also make hiding places for any fish. Try not to throw pond-clearing chemicals into water. Just be patient and concentrate on getting the planting right.

The planting of water gardens should be approached in a similar way to a terrestrial garden. Simple repetition of selected plants, rather than a collection of many varieties, will give a more designed look to the garden as a whole.

Water plants are basically split into three groups — oxygenators, marginals and aquatics. Oxygenators are fully submerged and will help to keep the water clear. Canadian pondweed Lagarosiphon major and Ceratophyllum demersum are two of the most reliable and quick-spreading oxygenators. They generally come with small weights so they sink to the bottom immediately and quickly multiply.

Marginals include Typha minima, a dwarf bullrush with a stiffly upright stem and strong, simple outline. The arum lily, Zantedeschia aethiopica, is a reliably flowering stately plant that can be grown successfully as a bog plant or a marginal. It has an unmistakable creamy-white spathe in early summer.

Sagittaria sagittifolia has the most elegant, arrow-shaped leaves and quickly forms dense clumps. The loose clusters of white three-petalled flowers appear as an added bonus in mid-to-late summer.

Aquatic plants include the water hawthorn, aponogeton, which is planted to a depth of up to 75cm. Its dark green long and oval leaves float on the surface of the water. The unusual forked white flower spikes have a strong vanilla fragrance. Another group of aquatic plants with leaves that float on the surface are the much-loved water lilies. There is a water lily to suit every pond size and they come in a wide range of colours. They need quite a bit of sun to flower and prefer still water.

Plants and pumps:
Bromfield Aquatics, 01462 457 399, www.bromfieldaquatics.co.uk;
Stapeley Water Gardens, 01270 623 868, www.stapeleywatergardens.com.

Liners:
Butyl Products, 01277 653 281, www.butylproducts.co.uk.

Child-safe grids:
Safapond, 01623 428 873, www.safapond.com.

Society of Garden Designers, 01989 566 695, www.sgd.org.uk  

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Growing water lettuces in an ornamental garden pool

Water lettuce (Pistia stratiotes) is a floating aquatic plant that forms an evergreen rosette of blue-green leaves. It is native to tropical regions and, in this country, is too tender to survive outdoors all year round. However, water lettuces can spend the summer months in the garden, as long as the pool is situated in a warm and sunny spot and the plants are positioned on the water’s surface once the fear of frost has passed — early June is ideal.

Lift the plants out of the pool in September and place them in a plastic container filled with water (from the pool) and a little aquatic compost. Overwinter in a well-lit greenhouse or conservatory at a minimum temperature of 10C. Water lettuces are available from Maidenhead Aquatics (01344 453 666, www.fishkeeper.co.uk).  

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1.

A shallow trough filled with floating aquatic plants makes a delightful water feature for the garden or terrace. Choose easy-to-grow, maintenance-free varieties, such as water hyacinth (Eichhornia crassipes) for its spikes of lavender flowers; the sword-like rosettes of water soldier; or the tiny, fern-like mats of fairy moss.

2.

Select a decorative, watertight container at least 6in deep (a stone trough is ideal) and position on a flat surface in a sheltered, sunny spot. Fill the container to within 1in of the rim with fresh water and scatter a few handfuls of aquatic compost in the bottom – this will provide nutrients for the plants.

Allow the water to settle for a few hours until it reaches the outside temperature, then place the floating plants on the surface.

In warm weather, keep the water level topped up and always scoop out any algae or debris with a fishing net.

Most of the plants are slightly tender, so remove them from the trough in the autumn and overwinter in old ice cream cartons filled with water and a little aquatic soil in a well-lit, frost-free spot, such as a conservatory or greenhouse. Replace the water occasionally to prevent it from becoming stagnant.

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Both the Water Hyacinth (Eichornia crassipes) and the Water Lettuce (Pista stratiotes) are tender floating aquatic plants from the tropics which require a hot summer to succeed. Unfortunately, they will only survive the winter if protected indoors.

The Water Hyacinth is a beautiful plant with glossy green leaves and striking blue and lilac flowers. Each plant can produce a series of plantlets over the summer, and it is these that are over-wintered and the parent plants usually discarded. The Water Lettuce also produces small plantlets and is treated similarly. The velvety green foliage of this unusual plant gives no hint that it is a member of the arum family, as the flowers are also quite insignificant.

The plantlets of these tender plant species should be taken inside at the end of September and over-wintered in an aquarium or in pans of moist heat until they burst unto growth the following May.

There are two hardy forms of floating plant that you might like to consider as alternatives. One is the Water Soldier (Stratiodes aloides), an extraordinary plant with rosettes of leaves that resemble a pineapple top. It spends the winter submerged on the bottom of the pond and floats to the surface each spring to form dense colonies. Although not as striking as the Water Hyacinth, its large creamy white flowers are very decorative. The other plant is the Water Chestnut (Trapa natans), which forms rosettes of serrated edged shiny leaves that float on the surface and are complimented by pretty small white flowers. This plant dies back in winter and renews itself by seeding freely in the pond. You can, if you wish, gather some of the ripe fruits in the autumn and over-winter these indoors in a bowl of water as insurance against a severe winter.

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Holes eaten into water lilies. Is it the fish?

The damage has been caused by the water-lily beetle. The adults are small and brown in colour and emerge in early summer to lay eggs on the foliage. Black grubs soon hatch and, along with the adults, eat furrows and holes in the upper surface of the leaves — eventually the foliage will shrivel and rot. A cure for this problem is not easy but you should remove badly affected leaves and then use jets of water (from a hosepipe) to knock the beetles and their grubs off the remaining foliage and into the water — the fish will then eat them. This process may have to be repeated several times, as the beetles can have two or three generations in a season. The adult beetles hibernate in vegetation at the side of the pool, so clear away plant debris and dead growth from marginal plants in the autumn.

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Growing a water lily in a small container. Which varieties can to use?

Dwarf water lilies are the most suitable for waterproof containers or wooden half-barrels, as long as they are positioned in a sunny, sheltered spot in the garden. Bear in mind that they need to be planted at a depth of between 4in and 10in, and spread about 1ft to 2ft over the water surface. The best ones are Nymphaea tetragona, which has star-shaped white blooms and leaves with purple undersides, and Nymphaea ‘Pygmaea Helvola’ for its long-lasting pale yellow flowers. The ideal time for planting is late spring, as they lie dormant during the autumn and winter and can be prone to damage if placed in a container while the water temperature is close to freezing.

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