Water gardens and water quality

reprinted by kind permission of Peter J May, the Perfect Pond Detective

Hi, it’s the merry month of May,

Water Garden Chronicles time again. A bit late this month, but the excuse is that this is the month things really notch into gear in the UK. My time has been taken up with trying to keep ahead of the deadlines on articles and also getting a look in on the flurry of Flower Shows that starts in May. They are always good for new planting ideas and the show gardens, which always have a water garden as a centrepiece or focal point, are a fantasia of landscaping ideas. For those of you desperate for inspiration on the water garden design line check out the Royal Horticultural Society website . The RHS organise all the biggest shows in the UK, starting the season off with the Malvern Spring Flower Show. The Malvern Spring Flower Show has just happened but the gem of gems of all flower shows in the world is the Chelsea Flower Show starting on the 20th May. They will have all the major gardens on display on the website and some of them will be in ‘360degree-zoom-in- zoom-out’ mode. The Hampton Court Flower Show at the beginning of July is particularly inspirational for water gardeners because there is a special section of display gardens that are exclusively water gardens. As flower shows go, it is probably the biggest in the world.

I was giving a talk at one of the shows, the Alexander Palace Flower Show last Sunday. It was called “The Balancing Act With Plants”. Whether people came expecting to see me tight rope walking with a flowerpot in each hand, I don’t know, but I had a full auditorium. The main message I was tying to put over was that unless you resort to technology or chemicals the only way to keep the water clear in your pool is with plants. The Anglo Aquatic Company proved this the year before last at the Hampton Court Flower Show with ‘The Swimming Pond’. This was a 7ft deep pond in the middle with a huge planting of a complete range of water plants around the edge and these would be guaranteed to be effective in keeping the water clear for 90 percent of the year. The centre was kept clear of plants so that people could use the water to swim in which they did. One little girl spent the best part of day in there and said she it was a hundred times better than a chlorinated pool because she would never have been able to stay that long in a chemically cleansed pool. Apparently ‘Swimming Ponds’ are ‘big’ in Austria were there over 8,000 of them!
In your own fish pool or wildlife pool, the same applies with plants, but here the most important plants are the oxygenators. The underwater plants that feed the environment with oxygen that is not only essential for the wildlife of the pool but also the bacteria that inhabit the bottom breaking up the muck and detritus that ends up there into nitrates, chemical that can be ingested by the plants as plant food. This is one of the essential cycles of life that makes your pool or pond a completely self sufficient little world. Algae that in profusion cause the green water we have all commonly grown to accept would consume the nitrates eagerly, so what is required is a range of other higher plants that can get to them first.
After the oxygenators there are the lilies and other deep water aquatics that are gross feeders of these nitrates in quantity. They also provide a bit of shade for the pool that discourages the growth of algae, which need sunlight as much as any other plant life. Floating plants too are useful but many of you over in the States and South Africa have ‘hit list’ of dreaded floating plants, so choose with care. Then there are the marginals. These blend the water garden into the rest of the garden, softening the edges and provide cover for wildlife. Also many of them are amazing at helping keep the water clear although it does tend to be the ones that get out of hand, growth wise. It’s a bit like using Hells Angels as bouncers at party, they are great at doing the job until the point they decide ‘they’re going to party’. The best one, one that actually oxygenates water and absorbs all sorts of toxins, not only the nitrates but including radiation, is the humble common Reed. In the UK it is known as the Norfolk Reed because it has taken over Norfolk and most of Suffolk and most anywhere else it goes in the world as its Latin name testifies Phragmites australis.
The other point that I was making in my talk was that although some of these plants are pretty tough wily old birds which given the light of day just completely take over, in fact virtually any water plant will take over a pool without any competition about, it is by taking a balance of plants from across the spectrum of all these water garden types that helps keep them all under some sort of control.

Jobs for the month.
Keep your eyes peeled for the herons. A lot of my customers and clients are having problems with herons as building developments of flood plains forces them to exploit new habitats. If you fish have disappeared from view and lurk shyly in the bottom of the pool and don’t feed, suspect you’ve had a visit. Look into ‘heron scarers’.
Now you can go to town adding new plants to the pool. A good time to get lilies and or divide them now,
Check new plants for clusters of snail’s eggs. You don’t want them to end up as fodder for these pests. If you are going to have snails get the ramshorn shaped ones. There are much less likely to consume your water hawthorn and oxygenators.
Watch for fish spawning . If the pool is highly populated, you could rescue some and hatch it in a tank.
Now is the time that everything seems literally burgeoning and if the problem of algae does not begin to subside then if you do something about it now then you can push the balance over to a more favourable position. Start with ecological solutions like eco algicides, barley straw and extra plants before the heavy chemicals and the mechanical technology. If you live in a hot sunny part of the world then you will have had to resort to biofilter technology as a routine. I will go into this a little more some time in the future, so be patient especially if you are just starting up. It can take anything up to 6 or 8 weeks to get that old nitrogen cycle rolling.

Plants looking good are the Water Hawthorn (Aponogeton distachyos), Bog Bean (Menyanthes trifoliate), the foliage of Houttynia cordata in all its forms is looking good and there’s good looking Hostas out in the bog garden along with the Globe Flower (Trollius europaeus). The double Marsh Marigold (Caltha palustris plena) is following in the wake of its cousin. Lots more to come by the end of the month including some of the Irises.

So good ponding, and I’ll speak to you soon.
Pete