Dig it Part 5, How to Put in a Garden Pond Part 7. Water Plants

WATER PLANTS AND PLANTING THE TYPES and THE CHOICE

NEW POND, NEW WORLD

The moment your new water garden begins to fill with water is the creation of a new environment in the garden. Here is a place for new possibilities but if left to its own devices would very quickly turn into a noxious lagoon of pea green slime. I am not knocking algae, even though algae in the form of microscopic single celled plants are what cause the green hue and goo, they are also responsible as a whole for the production of most of the oxygen on this planet. Algae have their place in the cycle of life in every pond, but they do need to be restricted. Like any bare piece of ground in a garden, if the gardener does not put in his own plants then nature takes over with what we usually regard as weeds. Algae are effectively the 'weeds' of water and can only be restricted with competition and suppressed by encouraging the growth of other plants in the environment. These higher plants have other functions too and they all work together to ensure a healthy environment in which all the animals and plants themselves can flourish.
Some plants produce oxygen in the pool for the aquatic life. Any plant that grows below the surface of the water will produce oxygen as a by-product of its natural photosynthesis. This is the process by which the plant manufactures sugars for its own growth and sustenance when the green chlorophyll in the plant leaves reacts to sunlight. One of the most important uses for this oxygen is in the breakdown of organic matter in the bottom of the pool. As plant detritus, fish muck and uneaten food sinks to the bottom of the pool it is decomposed by fungi and bacteria. A lot of this would be broken down to poisonous Ammonia compounds if it were not for the Nitrosomonas bacteria, which with the use of oxygen convert these chemicals to nitrite compounds. These are still pretty poisonous, but hopefully there are Nitrobacter bacteria on hand, again using the presence of oxygen, that convert Nitrites to Nitrates. Nitrates are the perfect food for plants, and if there are plenty of plants on hand to make use of them, they take them up before opportunistic algae use them. The plants flourish and then die and so the circle continues. Meanwhile these other plants provide cover to the water surface restricting sunlight to the algae and providing somewhere to hide for fish and animals. Nitrosononas and Nitrobacter that are oxygen dependent are described as aerobic bacteria. There is a process by which the nitrates, can be broken down further to oxygen and nitrogen in a much slower process by bacteria that are not in fact oxygen dependent, i.e. anaerobic, but as nitrates are readily taken in by most plants and used for growth then it is as well to have efficient plants for doing this in residence.

This is in fact a subtle balancing act and although some plants are really good at taking up nitrates they do tend to be very strong growers. Because of this it is best to have as wide a range of species as possible to inhibit those of more rampant habits. Unfortunately for some people it seems that the pool is just beginning to look completely overgrown before a reliable balance is achieved, because to keep the water in your pool clear, altogether there must be two thirds of the pool surface covered with plants or oxygenators just below the surface. If you feel too much plant life will obscure your view of the fish then I am afraid, if want to guarantee seeing them, then you must resort to technology. (see Filtration later in the year)

FILLING THE POND

If you are filling your pond with tap water - it is dead inert stuff, it has plenty of mineral nutrition for algae, but not much else - leave it for two to three days for the chlorines to waste away and a few of the other additives and minerals to drop out.

A successful pond.....

....is not just about...

....what you see!

These things will help to discourage an almost inevitable algae bloom that comes after 3 to 10 days and lasts for about a month. Do not be discouraged by this, at least when this happens you know the water will sustain life. To make doubly certain of this, you must check the pH before you put in any fish with a water testing kit available from any aquatic dealer. If the pH remains high above the level of the ordinary tap water and the hue has an almost creaminess in the green, then there may lime leaching in from cement or stonework. Several changes of water may be necessary before you can keep this down. Better to do it now than when you have got all the prospective residents of the pond lined up to go in. Also there is nothing the dreaded blanket weed, the cotton woolly filamentous algae, appreciates more than a 'limey' pond.

ESSENTIAL INGREDIENTS

For a healthy and balanced pond you need four basic ingredients or classifications of plants:

What do you do if you inherit a pond?

Oxygenators - properly known as submerged aquatics, which are basically any plants that are happy with their foliage submerged. Usually these plants will absorb all they need in terms of carbonNymphaea Masaniello dioxide and oxygen and nutrients directly from the water through the surface of their leaves and often the whole surface of the plant. During the day time they will be absorbing carbon dioxide from the water and giving off the life sustaining oxygen for the fish, fauna and bacteria in the pool.

Deep water aquatics have their roots in the bottom of the pool and their leaves floating on the surface. Generally speaking these include the water lilies, Aponogeton distachyos or Water Hawthorn and the Nuphars and Nymphoides peltata, which are close relatives of the Water lily. All of them provide very useful surface cover for the pool by inhibiting the sunlight that would encourage algae to proliferate and providing protective cover for the fish and other animals.

Marginal plants provide protective cover too, especially for animals going to and from the pool. Their other uses in the pool environment are that they are great users of nutrients and also serve to ‘landscape’ the pool into the garden scene. They are called ‘marginals’ because they are generally planted around the margins of the pool, however, many of them they are tolerant of a quite range of water depths and in some cases even dry ground. For our purposes they thrive in depths of water between 5 and 15cm above the soil they are planted in. This tolerance distinguishes them from Bog plants in that these will only tolerate moist soil where the water is draining away from the plant and not in a static slop.

Floating plants: they provide cover to the pool surface and use up nutrients, some of them having an almost magical effect on water clarity.

Animals and insects that are part of the very essence of a healthy pool or pond come of their own accord whether you want them to or not. This is part of the magic and wonder of water gardening. They wont feel welcome though if the plants are not there in force to greet them!