Plants for the Garden Pond

The attraction of a good pond is about far more than just the water. Once the pond is installed you can grow a wonderful selection of aquatic and moisture-loving plants with colourful flowers and foliage that combine to make your pond a truly stunning feature. Not only are aquatic plants immensely ornamental, but they are also essential for creating a balance of nature in your pond, ensuring that it stays healthy with the minimum of maintenance. Aquatic and moisture-loving plants are broadly divided into the following five groups:

  1. oxygenating plants
  2. floating aquatics
  3. flowering aquatics
  4. marginal plants
  5. bog garden plants

Oxygenating plants

The reason we have pondweed, or oxygenating plants, in our ponds is because they provide oxygen. This helps to keep the water stable and in good condition. Of all the plants we can add to our ponds, oxygenators are perhaps the least interesting, yet they are almost certainly the most important and should always be included.

By day, oxygenators convert dissolved carbon dioxide, given off by the fish, into oxygen. They also consume minerals and nutrients that otherwise would be used by opportunist and troublesome algae. A good selection of oxygenating plants will also provide effective cover for all manner of water creatures —protecting fish against marauding herons, and providing spawning grounds for fish as well as amphibious and insectivorous wildlife.

Most garden centres will offer oxygenating plants, normally kept in outside tanks, and generally sold as small bunches of stems linked by a lead weight (which often is not sufficient to carry the bunches to the bottom of the pond where they will root, so it is a good idea to supplement this weight by attaching a pebble to the bunch with an elastic band). You just have to drop these bunches into the pond — you don’t need planting baskets or compost. The weights will take the plants down, where they will find their own level (depending on the amount of leaves) and start to grow.

Most oxygenators will grow rapidly, especially in warm summers, and can cause the pond to become congested. You should, therefore, hook out a few bucketsful of excess ‘weed’, and perhaps do this two, or even three times during the summer period. This will, curiously, make the weed grow faster, and in turn make it more efficient at filtering and conditioning the water.

Carefully check through the foliage as you are removing it. Spread it out by the side of the pond and leave it for a day, so that any creatures caught up in it can crawl back into the water.

Floating aquatics

Floating water plants really are floating plants —they are not anchored by roots, although some do produce a few straggly roots that just dangle in the water. Consequently, they do not require ‘planting’ in the usual sense.

Aquatic plants such as waterlilies — have floating leaves but roots which are firmly anchored in pots or in the soil at the bottom of the pond. There are, however, plenty of free-floaters, with no discernible rooting or anchorage, such as water hyacinth (Eichhornia), duckweed (Lemna) and water chestnut. ‘Floaters’ actually help to maintain clear water; by blocking out some of the sunlight, they effectively check the development of algae — miniscule plant cells that are at their most prolific in well-lit water. As with the oxygenators, floating plants also offer refuge for small aquatic creatures, which can hide in comparative safety in the warmer waters just beneath the surface. These plants tend to die down during late autumn, to survive the winter as dormant ‘buds’, resting in the mud at the bottom of the pond. In spring, when the weather warms, they burst into life again.

Some floating plants increase their size and number rapidly and, as with the oxygenators, can cause overcrowding in the pond. It is for this reason that there is a restriction in the sale of such plants in some warmer climates, including some of the southern US states, where the winters offer less of a check to their growth.

Flowering ‘aquatics

Flowering aquatics grow within the pond, anchored in the mud, or in planting containers. Depending on the plant, they will need a water depth of anything from 30cm (12in) to 1.2m (4ft), or even more in the case of some vigorous species.

Flowering aquatic plants generally produce leaves and flowers that sit on top of the water or rise above it. Waterlilies are the classic flowering water plant, and they typify one of the most important aspects of the group, in that the vigour of their surface spread, and the depth of water to which they are most suited means they must be chosen with great care.

Marginal plants

Gardeners have argued for years over the true definition of a ‘marginal’ plant. Some say it is the sort of plant that always has its roots in soil under water. Others say that it is a plant that has its roots in soil that is permanently moist, whilst others even maintain that it is a plant that has its roots growing in soil that is either wet or under water, but which in arid conditions dries out completely.

Water lily in full bloom

Image via Wikipedia

In reality a ‘marginal’ should be considered to be any plant that grows at the very edge of the water, regardless of the moisture content of the soil in which it is growing. This means that the marginal plants discussed later will have a wide range of habitat requirements, spanning all soil conditions from being permanently under water to semi-dry. If we are not careful, however, marginal plants will graduate, almost imperceptibly, into bog garden plants.

Bog garden plants

Bog garden plants — sometimes referred to as marsh or poolside plants — generally dislike dry, clay soil that can turn concrete-like in hot, dry weather. Also, they tend not to perform well if they are in a position exposed to high winds and the full strength of the sun all day long. Other than that, they enjoy a wide and varied selection of growing conditions.

Many have colourful flowers and lush, attractive foliage, and they make the perfect transition between pond and garden (as long as the soil is moist).

07. March 2012 by admin
Categories: Garden Ponds, Plants, Water Garden Plants | Tags: , , | Comments Off on Plants for the Garden Pond

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