Creating a Garden Pond – Part 2
Welcome back to my blog on garden ponds. If you have followed the first blog from last month you have reached the stage, either in theory or practice, where you have a lined hole which is full of water but is not yet a pond! You may also have finished off edging the pond with your chosen materials and may even have gone further by constructing a waterfall and/or stream course on a raised area at one end of the pond. Such features can of course be made from scratch by using sections of flexible liner, rocks and mortar but they are also available as pre-formed sections in plastic or fibreglass. Have a look on line to see what is available if this is something that you think would enhance your pond but don’t forget that even without these you can still have movement of water in the pond with a basic pump and fountain.
From this in April 2018 to this in April 2019!
The white flowers are those of the Water Crowfoot, the yellow flowers are Marsh Marigold
Now we move on to the stage of bringing the pond to life, something which will begin to happen naturally as soon as the water is added. Birds will start to use the pond for drinking and bathing and some insects will appear as if by magic. However, it is the addition of plants which really transforms any pond and for me, and I suspect most other gardeners, a pond without plants is of little interest except perhaps to Koi carp specialists so it is worth spending a bit of time and thought in getting the planting right. There are basically three types of plant which ponds need in order to be healthy, attractive and balanced- Surface water plants, Oxygenating plants and Marginal plants, some plants falling into more than one of these groups. The easiest and first group to get established are the oxygenators. These as the name suggests produce oxygen during the process of photosynthesis and therefore sustain all the insect and animal life of the pond. However, they bring many other benefits in addition, for example by absorbing mineral salts in their growth they help to control the growth of algae by competing for their food source. They also provide food, shelter and spawning sites for pond organisms as well as absorbing waste products from organisms such as fish which they convert into plant proteins. These oxygenators are usually sold as bunches of unrooted cuttings held together at the base by a piece of lead and as such can simply be placed in the pond and allowed to sink to the bottom. As they get their nutrients directly from the water they don’t have to be in soil although they will root into any soil which in time builds up on the bottom of the pond. They can also be planted into plant crates or baskets and then placed in the shallower parts of the pond or on planting shelves around the edge. For garden ponds, especially smaller ones, planting in these baskets is preferable to planting into layers or pockets of soil within the pond. Plants grow extremely well in ponds and some can become unmanageable very quickly if given a free rein. Planting in baskets allows the gardener to control this growth when necessary and as we do in the rest of the garden to act as a referee in the battle between plants. These planting baskets are black, perforated plastic containers in various shapes and sizes and can be used for all three groups of plants. Rather than using garden soil or potting compost which generally have too much organic matter and fertiliser it is best to use a special aquatic compost covered with a layer of gravel. With a new pond it is generally recommended that around five bunches of oxygenators are used for every square metre of water surface area so finding a friend with a pond and spare plants is always a good idea. In established ponds by April/May time the water is warming and with more sunlight the oxygenators will be growing strongly and often need to be thinned out in the spring and summer so plenty are available either for giving to friends or to put on the compost heap. As with any pond plants destined for composting just leave them at the edge of the pond overnight so that any pond life can return safely to the water. Some oxygenators are very fast growing and might even be considered to be invasive so my advice is to choose carefully. For many years the only one I ever saw available for sale was Canadian Pondweed (Elodea canadensis) which is still widely available but in my mind rather too fast growing especially for a small pond. I prefer to use British natives such as Water Crowfoot (Ranunculus aquatilis) which has two types of leaves, the submerged foliage which is finely dissected and the aerial or surface foliage with its three-lobed leaves. In addition in spring the surface growth is covered with many five-petalled, snow-white, yellow-centred flowers. Another good oxygenator if you can get it is Hornwort (Ceratophyllum demersum) with dark green, toothed leaves which float just below the water surface. As you can see from these descriptions both of these plants are not only oxygenators but are also surface water plants.
Surface water plants are also vital for the overall health and balance of the pond and need to be added as early as possible to the new pond. They reduce the amount of light entering the water which in turn reduces the growth of algae as well as competing with the algae for the available mineral salts. In the period of May to September it is generally considered that between a half and two thirds of the water surface should be covered by some form of surface leaf in order to keep the algae growth in check. Most people in terms of surface plants immediately think of water lilies and these are certainly great surface plants but there are many others such as the two oxygenators which I have already mentioned. As for the water lily itself it is thanks largely to the Frenchman Joseph Latour-Marliac working in the latter part of the 19th century that there are now many wonderful hybrids available which are suitable for different sizes and depths of ponds. We went for two of the medium growers for our 8ft by 5ft by 2.5ft pond (2.4mx1.5mx0.8m) with a view to covering about third to a half of the surface area. These were Nymphaea ‘Gonnere’ with double, white flowers and golden-yellow anthers and N. x marliacea ‘Chromatella’ which has yellow flowers and reddish-brown mottled leaves. Water lilies are best planted in square or round baskets so that they can be lifted every 3 or 4 years for the soil to be replaced and which can easily be lowered gradually the bottom of the pond as they mature. At planting time the basket should be placed on a shelf or brick so that the leaves are floating on or near the surface and lowered into the pond further when the leaves start growing above the water surface. In spring each year I push a couple of slow release fertiliser tablets into the container of each plant which seems to keep them flowering well. Individual flowers don’t last very long but as they open out over a few days they are spectacular before they begin to sink back below the surface. I usually remove the flower spike at this stage to reduce the build-up of organic matter in the pond. There are some other good surface water plants apart from the water lilies and I think two of the best are Water Hawthorn (Aponogeton distachyos) and Floating Heart (Nymphoides peltatum). Water Hawthorn has elongated leaves and beautifully scented, white flowers with black anthers. It is best started off in water that is no more than 6” (15 cms) deep and then later moved to deeper water, up to 18”(45 cms) as it matures. Floating Heart is a small floating plant which resembles a small water lily with its rounded, green leaves and dainty yellow flowers which are held clear of the water, planting depth 4-18” (10-45 cms).
Nymphaea x marliacea ‘Chromatella’ and Water Crowfoot flowers and the beautiful N. ‘Gonnere’
The third group of plants, the marginals, are planted more for their aesthetic value than for establishing good water quality although they do provide shade, shelter and cover for a range of water organisms and as they also take nutrients from the water they help to reduce the growth of algae by competing for food. They are referred to as ‘marginals’ because most are happy in the shallower water at the edges of ponds which is why planting shelves at different depths are built into pond construction. Different plants have they own preferred planting depths which refer to the depth of water above the crown of the plant ie. above the top of the planting basket. Their great attraction for the gardener is that between them they can offer flower colour for long periods, many have vertical shapes which contrast well with the horizontal shapes offered by the surface plants, they provide homes for many insects and small creatures and they soften the often hard edges of ponds with their different styles of growth and shapes and sizes of leaves. There are many to choose from, arrive in garden centres in late April and into May and are usually clearly labelled in terms of planting depth. Some of my personal favourites include the Marsh Marigold (Caltha palustris) with its very pretty, yellow, buttercup-like flowers in spring and sometimes again in autumn, the blue flowered Brooklime (Veronica beccabunga) which grows out across the pond as a surface raft giving good cover for fish and other creatures, Dwarf Spearwort (Ranunculus flammula) with its narrow green leaves and small yellow flowers throughout the summer, the Pickeral plant (Pontaderia cordata) with its glossy, pointed, green leaves and pink flower spikes and the Flowering Rush (Butomus umbellatus) with its narrow green leaves which start bronze-purple followed by umbels of pink flowers held well above the water on strong, wiry stems. The latter is a good example of the vertical shapes which Rushes, Reeds, Irises and Reedmaces will also provide but beware some are very strong growing such as the native yellow Flag Iris and are best avoided for garden ponds. We chose the Japanese Rush (Acorus gramineus), Reed Sweet Grass (Glyceria maxima) and the miniature Reedmace or Bullrush (Typha minina). We also grow some other grasses in the ordinary garden soil just outside the pond which help to suggest that the pond is larger than it actually is.
Showing some of the vertical shapes provided by marginal plants. The large grass on the right is actually a Miscanthus planted outside the pond.
The white flower in the centre is Water Crowfoot with its rounded surface leaves. The plant in the upper left is new growth and roots on Brooklime and in the upper right is the submerged, dissected foliage of the oxygenator Hornwort. In the bottom right is Nymphaea ‘Chromatella’.
Brooklime with its blue flowers, Hornwort and Nymphaea ‘Chromatella’.
As you can hopefully see from the above the planting up of the pond can be a really interesting part of the project and will really make the pond come alive and become an integral part of the whole garden. However, can I just add a word of warning concerning pond plants. Try at all costs to avoid any invasive plants many of which come from overseas as they will quickly choke the pond and if they get into the wider water system can lead to problems for our native plants and wildlife. These include:- New Zealand Pygmy Weed (Crassula helmsii), Parrot’s Feather (Myrophyllum aquaticum), Water Fern (Azolla filiculoides), Floating Pennywort (Hydrocotyle ranunculoides) and all of the Horse Tails (Equisetum).
By the time you get to this stage in the creation of the pond the final stage of the process will have already begun without much help from you! I refer of course to the life of the pond. Almost as soon as it was filled the pond will have begun to attract insects and usually the first to appear are the Pond Skaters and Water Boatmen. Also by adding plants to the pond many creatures will arrive with them such as snails, or at least snail eggs, especially if you have managed to get some plants from a friend’s pond. Snails by the way are to be welcomed into the pond unlike into the rest of the garden as they tend to eat decaying vegetation as well as the unwelcome algae. If you can also try to get some water and mud from an existing pond as these will introduce many forms of microscopic life. This helps to establish the new ecosystem literally from the bottom up which will in turn attract creatures higher up the food chain such as insects like Damsel and Dragonflies and the amphibians such as toads, newts and frogs which when not in the pond will be doing a great deal of good in the rest of the garden! All these and the water itself will in turn attract other creatures such as birds to drink and bathe, hedgehogs and other mammals to drink and larger birds to search for food. Although it is hard to watch, this year I saw Blackbirds trying to pick off tadpoles and Magpies pulling newts out of the pond margins. Actually if the truth be known I spend hours watching the wildlife in and around the pond and take great pleasure from it. From April to September there is always something to catch the eye.
I also love watching fish but I know that the pond won’t be as rich in wildlife if I introduce fish to it so I have resisted the temptation, so far at least! However, I accept that for many people the main reason for having a pond is to keep fish in it and this is the stage in the process now that the pond has had a chance to mature when fish can be added. I would just suggest keeping the stocking levels low so that the rest of the pond life has a chance to live alongside the fish. Fish also create a good deal of waste material so if you haven’t already thought about if before this is a good time to consider adding a pump, filter system and fountain or even a small waterfall. Not only does this add to the attraction of the pond by creating movement and sound it will keep the water well aerated and much cleaner. Good aeration is vital in the warmer months especially if there are quite a few fish as warm water can hold less oxygen than cooler water. We chose to add a pump even though there are no fish simply for the movement, sound and better water quality. There are of course lots of different pumps and filter systems to choose from but unless you are keeping Koi carp the simplest solution is to go for a combined, in-pool unit. This comprises a pump, built-in filter system and an ultra-violet bulb. Our pump pushes water up a hidden pipe to the back of a small waterfall, the water then falls back into the pond to create movement and sound and at some stage is sucked back into the pump. It is then forced through the filter system and passed the ultra-violet light which kills off any algae. The filters do need cleaning from time to time but I find that once a year in spring is enough (it would need to be more often if we had fish) and the bulb does need replacing again about once a year but the resulting water quality is really good and is well worth the effort. We only run the system when we are in the garden to hear and see the movement but this seems to be enough to do the job. As I mentioned earlier electricity and water do not mix well so get professional help if you don’t feel competent yourself. For our power supply we run the cable from the pump through a protective pipe to the power supply in the nearby shed so that there are no outside connections. If you do have such connections they must be made with waterproof connectors and when I have used them in the past I have always placed them in some form of plastic box for extra protection.
At this point you have the beginnings of a real pond and not just a hole full of water and within only a few weeks and months it will begin to look as though it has been there for ages. I never cease to be amazed at how quickly ponds mature. You will now be able to sit back and enjoy all the plants and wildlife which it will no doubt deliver. As with all gardening, however, there are a few jobs which need to be carried out during the year but none are very onerous and I find that they just give me more opportunities to pond gaze! There is not a lot to do until March and April apart from ensuring that at times when the pond is frozen over that a patch of water remains open so that gas exchange between the water and air can take place. This is especially important if the pond is stocked with fish. The simplest way is to drop a ball into the water, even something as small as a tennis ball will do, which will be moved slightly by currents and the wind so that the area immediately around the ball remains unfrozen. If it gets too cold for this to work then simply, as I have been doing during the cold spell of the last few days, place a plastic tub on the ice and pour hot water into it. This will melt a hole through which gas exchange can take place. Please don’t be tempted to physically break the ice as shock waves through the water are not welcomed by its inhabitants! For fish ponds, particularly those with expensive Koi carp, a pond heater can be used to keep a small area ice free. These float in the water in a polystyrene collar but obviously need to be connected to an electricity supply. By March and April the pond will be coming back to life as the days lengthen and the water warms. Any old growth on the marginal plants can be removed at this time as the plants begin to show growth and some like the Marsh Marigold actually flower. This is also a good time before the plants put on too much growth to clean out the pump filter, change the UV bulb if necessary and to feed the water lilies. I also remove any leaves and other dead vegetation which I can easily reach but just remember to leave this on the side of the pond overnight as even at this time of year there will be pond creatures mixed in with it. After this tidy up I tend to leave the pond alone so that its life can get on with making new life unhindered by me! However, this doesn’t stop me from enjoying seeing the signs of all this new life in frogspawn, tadpoles and newtlets (probably my own word for them!)as well as the insect life. If you have fish this is the time to start thinking about feeding them again after the winter break. As the water warms they will become more active and can be given a little food which can be gradually increased over the next few weeks. Just one word of warning with feeding fish, don’t be tempted to overfeed, give them an amount which they finish off in say 5 minutes. If you give them too much and it remains uneaten it adds a lot of nutrients to the pond which will encourage algae growth. By May and June the breeding season is largely over and the main pond task is to thin out the rapidly growing pond plants, repot older water lilies and perhaps to add a few new plants. The second and third week in May are generally considered to be the best time for this as the water will not be too cold for you to work and for the plants they have the whole growing season in front of them. As the weather warms it is important to run the pump to help aerate the water and stop algae becoming a problem and in dry spells to top the pond up with rainwater if at all possible. Ponds don’t suffer too much from pests and diseases but aphids can be a problem for some plants and the best way to deal with these is to wash them off the plants with a spray of just water, nothing else!, and let the pond life enjoy a little extra food! In July and August the main tasks are to keep the water well aerated and the pond topped up if possible. There may also be some blanket weed to remove as even a well- balanced pond can have problems in hot, sunny spells. The best way is just to twist it around a cane in order to lift it out of the water. Again leave it on the side overnight before composting it. There are chemicals available to combat blanket weed and algae in general but I like to avoid adding anything unnatural to the pond if I can. By September and October life in and around the pond is beginning to slow down and a little more tidying can be carried out. As leaves fade on the marginals they can be removed and the oxygenators can be thinned again if necessary. The tidying up of marginal plants and the removal of leaves from nearby trees is about all that can be done in November and December apart from watching out for ice in the pond. If you have fish they do not need to be fed after the beginning of November. Their metabolic rate drops as the water cools and they live of their stored fat until feeding starts again in March or April when they begin to show signs of activity.
So that is all there is to it to create a beautiful pond which will give you many hours of pleasure. I hope that these two blogs have inspired you to have a go. I am aware that I have only covered the basics of pond building and if you have any questions about aspects I haven’t covered please feel free to get in touch via the comments box at the end of this blog.
The next blog will be ‘The Garden in March’ when we can really get into this year’s growing season and all that it has to offer. Until then keep safe and well and good gardening.