Water garden in November
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reprinted by kind permission of Peter J May, the Perfect Pond Detective Hello, its me again, with what to do in the water garden in November. In the UK, normally the season of mellow fruitfulness is over and the feeling and look of a grey blanket settles over everything. The relatively hot summer has given a spectacular autumn display of colour, especially from the Beech trees that has lasted much later than usual, but the grey blanket has settled over everything today. It’s not cold though. Not so cold that the pools, ponds and water gardens have definitely gone to sleep. But remember if that water in the pool has cooled below 7°C, don’t feed your fish, especially the Koi, and between 7 and 10°C only feed your Koi either wheat-germ or some other top quality winter feed. Many people who have tall grassy plants around the pool and who haven’t cut them back are congratulating themselves because there is still cover for the wildlife that is still moving in and out of the pool, unable to settle down, but also it is looking very good. It is the first time I’ve really noticed an autumn blaze from the likes of Cyperus longus, Sweet Galingale and the indigenous species of Carex or sedges. Meanwhile the scented rush, Acorus calamus and its tufty variegated cousin Acorus gramineus have stayed evergreen.
If you do decide to cut back the undergrowth, cut it right down to water level. Leave the likes of Acorus and the Carex ‘Bowles Golden’ unless they are looking particularly sorry for themselves.
Now assuming that November does actually come up trumps with some seasonal weather we should be thinking in terms of the normal routine of cleaning out pumps and removing altogether in cold districts and storing away. If there is a biological filter, the filter pump should be repositioned onto the marginal shelf so that just the top few inches of water are being turned over, rather mixing up the whole lot. As water gets to around 4°c, it becomes its most dense and sinks to the bottom of the pool. Fish are quite content to live down in this water that is oxygen rich. If the water were to get any colder it would rise up in the pool (contrary to any physical behaviour of any other liquid or even water at higher temperatures) and as it approached the magical 0°C it would turn into the solid that we know as ice. This naturally enough is not to fishes’ liking. So, if we are turning over the whole volume of the pool through a filter or waterfall and the cool extremes at the surface, we would find the whole system cooling down like refrigerator down the temperatures at the surface. So try to keep the lower reaches of the pool undisturbed.
As things get colder the biological filter is operating less and less on a biological level. If conditions freeze then the filter needs to be stopped. When things warm up, and you turn the filter back on, it will be like a ‘two slug Russian Roulette’ as to whether it will or will not deposit toxic filth into the pond, at a time when it least can cope. So the best bet here is to clean it out now. Clean out the filth in the bottom with rain or pool water and rinse out the sponges and the filter medium. If you have an ultra violet clarifier that is easily detached, bring that in or make sure it is empty of water.
If the pool does ice over, don’t break the ice with hammer. This knocks the fish senseless. Two or three days ice wont do the fish any harm. If however there is a lot of muck in the bottom of the pool and there may be a build up of noxious gases in this time, sit a pan of hot water on top of surface until it melts a nice hole. This will enable any build up of gas to be released. It will also relieve the stress the ice may be causing on the fabric of the pool liner or its structure. These are the two reasons many people float something soft and rubbery in the pool as a guard against mild freezing. Twenty years ago, a friend of mine called Charles Maplethorpe invented a device that was a ring of polystyrene that held a small round aquatic plant basket of pebbles in the centre. The pebbles were half submerged and cocooned in the insulating polystyrene float that formed a frost-free link with the water and the outside air. This worked to surprisingly low temperatures and sold in the thousands for years until lost its credibility one year of extremes temperatures when pools froze solid.
If it does get really cold, take Lobelia cardinalis under cover. By the way, if you’ve invested in any slightly exotic plants like Cannas or floaters like Eichornia crassipes – Water Hyacinthe (for those of you in the US and SA- yep! They actually grow them on purpose in the UK.) and Pistia stratiotes, Water Lettuce, take them into a frost free greenhouse and grow them in a tray. Water Hyacinthe can actually be planted up in a pot to make it more winter hardy.
Plants flowering at this time of year? The hardy South African Aponogeton distachyos- the water hawthorn, and in the bog the other plant from around there, Schizostylis coccinea, once commonly referred to as the Kaffir Lily, now it is considered more politically correct to refer to it as the River Lily. It is a fantastic show at any time of year, let alone blazing away in the dull washed-out blear of the sad grey English garden in winter.
Keep warm and dry. All the best Pete
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