Water garden calendar, June

June into July is the time for the most elegant of plants, the Irises in all its forms. Try to get to the Hampton Court Flower Show to see this plant in all its amazing variation from the true water iris, I. laevigata to the adaptable I. siberica, I. versicolor to the many forms of the Japanese iris, I. ensata.

Varieties of Iris ensata with Lysimachia punctata variegata at the Anglo Aquarium Plant garden at the 2005 Hampton Court Palace Flower Show.)

If youve have a potentially good harvest of froglets from tadpoles this year, now is the time that they will start to emerge from the pond and sit indecisively amongst the surrounding sward of lawn, so take care with your mower as you fly by the pool or fire up the barbeque in anticipation of a feast of mini frogs legs!

The European Edible Frog.

Of course this is the time of the year that Aquatic retailers eagerly await the return of their early season customers who only bought a pool and a few plants. They return in their droves looking for submersible pumps for fountains, waterfalls and filters. As the weather warms up, the new fish start gasping at the surface despite the new pond keepers following all the recommendations of getting in the right number of plants, especially oxygenators in the water.

REMINDER Allow one bunch of oxygenators per 0.2 sq m (2 sqft) of pool surface

Allow one lily for every 2.3 sq m (25 sqft) of pool surface.

Marginals: allow at least one plant for every 0.5sq m (5 sqft).

However in a new pool especially with Koi carp and even if it has a filter system, if the fish have been added before the whole system has matured, the pool has to go through a phase where the ammonia level rises before the bacteria that break down that ammonia, get well established. What I would propose as a good idea is to add one or two fish to start the whole process going because it is their faeces and fish food that produces the ammonia that the bacteria feed on. These are effectively Kamikaze fish, martyrs to pond environment in the sense that the environment you have introduced them to is going to go through some pretty unhealthy phases before it gets robust enough to support a full population of fish at 2inches per square foot of surface area. The worst bit is when then the ammonia is partly broken down to nitrite chemicals and you have a cocktail that is poisonous and damaging to the gills of the fish. This is when they start gasping. So you can see that they are in for a pretty rough time.

If you are in a position like this with a large or small population of fish struggling for survival, the best action is get plenty of oxygen in there. Large partial water changes are best, but just running water in hard from a hose is also good. The oxygen in the water will sustain the fish and the bacteria in the bottom of the pool, or the filter if you have one, with the essential oxygen they need to make the chemical break down.

The next phase is the break down by the bacteria of the pond detritus is conversion of the nitrites to nitrates. Once in the form of nitrates, the plants around and in the pond then greedily absorb the compounds.

So if you havent got a fountain or a waterfall and you have some precious fish recently installed, think about getting one if only for emergency oxygenation. And if you have created this watery habitat for the sake of some beloved fish, then seriously think about a biological pool filter, especially if it gets warm on a regular basis. You must also consider that without a filtration system, your pool needs to be two thirds covered by plants at this time of year in order to maintain a balance that ensure anywhere near clear water.

A simple fountain jet is one of the most effective water oxygenators, at the same time hypnotising.

So another reminder: allow 4 to 6 weeks for a pool to really establish its microbiology. There are proprietary pool starter mixes available to get things going more quickly, or you could try borrowing a couple of gallons of water from a friends pool that you have long since admired for its crystal clear water and lack of blanket weed. Apparently spitting into the pool can have the same effect! The bacteria we carry in our mouths are pretty much the same as those found in the bottom of a pond. Ahh! So thats what the smell is.

Jobs for the Month

1.Dead head early flowers like the Marsh Marigolds and irises. Now begins the period where water gardeners look enviously at their friends with bog gardens. These can work as a spectacular backdrop to a pool. The flower and foliage affects that can be achieved here carry on much further into the season. Even now some plants are only just beginning to come into flower; plants like the Day Lily Hemerocallis, Rodgersia, Ligularia and Hosta. However water gardeners still have their lilies to enjoy and these can still be planted.

2. This is the best time of year for planting out lilies. Some of the old time water gardeners would only think of planting lilies at this time of year.

3.Look for pests on leaves. Aphids can be abundant on lily leaves and marsh marigolds. Knock them of with a harsh sprayer or a finger and thumb. The fish will soon gobble them up.

July

If the weather gets really hot and the water in the pool is warming up, look to see if the fish are getting lethargic. If the fish look as though they are in distress, there is the emergency remedy of a partial water change of a third of the volume of pool water will do them the world of good. Alternatively blast fresh tap water in there from a height and let the pool just overflow. If you have a fountain or a stream, ensure it is running.

If it is a really well established pool, and a little (dare I say) sludgy on the bottom, the fish in these pools will be suffering the most, especially in the evenings; what makes the situation worse is that water will not retain oxygen very easily the warmer it gets. The bacteria in the sludge will be using up the oxygen, and any oxygenating plants, despite their worthy role of giving out oxygen during the day, come night-time they begin to take in oxygen as well. If there are Koi in there, theyll be using up the resources like nuclear subs and will be the first to be panicking on the surface.