I discovered quite by accident really, that one of my favourite herbs – the Vietnamese Coriander, normally grown in soil, and which has a lovely piquant aromatic flavour, also grows very well in several inches of water. Even when there is a thick covering of ice in the winter, the plant dies back but recovers again next year from some of the woody stems left underneath, eventually growing into a thicket of leaves that need to be harvested regularly to prevent it taking over.

Vietnamese Coriander and bogbean flower

So that’s one useful herb for growing in the pond, and another I’d like to mention is more obvious, and that’s watercress. Some of the garden centres, aquatic centres and pond shops seem to have a form of cress which is sold as an aquatic plant, or you may get given some from a neighbour, but I think it’s more important to get the right variety for culinary purposes so what I do is this. When I buy a bag of watercress in a plastic bag from a supermarket for use in salads, if there are any stemmy parts with white roots already growing out, I throw one or two pieces in the pond. They look a bit sad floating there on their sides, but in few days will find their feet and start spreading. Watercress is a useful water plant for filtering harmful nitrates out of the pond water in any case, but if it spreads well then you can cut and wash some for eating purposes, and the tiny white flowers are quiet attractive too. Like the vietnamese coriander, the watercress seemed to survive a frozen winter last year as well, but in previous years I have had to start all over again, which is easy enough given the method I have already mentioned.

So there are two edible plants which can be grown in a small garden pond. I wonder if you can suggest any more please?

I moved into a property about 3 months ago which had a small pond in the back garden. The approximate size of the pond is about 4ft x 3ft x 2ft. It had no filter, pump, or plants at the time, just the butyl liner in the hole in the ground and a disused waterfall feature. My wife was quite keen to have some fish so we put in about 20 small goldfish that we bought from a local garden centre with fish pond supplies. We also added a pump (1000 litres per hour) which I connected to the waterfall feature and sometimes switch over to a fountain. The pump does seem very underpowered as when I connect it to the waterfall there is little more than a dribble of water returning at the bottom to the main pond. We do leave the pump on 24/7. The fish have been fine for a couple of months, feeding well and seem healthy. However, now one or two of the fish have died and the others don’t seem well at all.They seem to congregate at the top near the edge of the pond as if they are gasping for air. I know that sounds daft as they are fish and don’t need air??? I would like to sort the problem out but don’t know what to buy. Do I need a filter? Do I need a bigger pump? Do I need plants (I have none). I have added two treatments to the pond, both Tetra products. One I add when I top up the water level with tap water which isn’t very often, and the other is an algae clear additive. I do live in the UK so temperature is dropping a bit now were approaching Winter….is that a factor? Any advice gratefully received… Regards Ed.

Well Ed, the good news is that you don’t need t spend any more money on gadgets from the fish pond supplies shop! Oh, is that bad news sorry!

You have too many fish for a small garden pond of that size, and as they grow they are demanding more oxygen than the surface of the pond can provide. Adding some plants may help, and will get rid of the need to add algicide which doesn’t seem like a very good idea anyway. But unfortunately, as the fish grow, with that number in the pond then there will be deaths until a sustainable population of about half a dozen is reached. It will usually be the largest fish that die first. So if you can take some of the fish out and give them away to somebody who has a a much larger pond, that would be a great idea. You could also see if teh fish pond supplies shop will take them back.

You’ll notice that the goldfish didn’t seem to like it much when the underwater camera was lowered into the fish pond. They went and hid under a stone. So the kind of technique we’ll need to look into more will entail leaving a camera on the bottom of the pond for some time, so that the fish and other pond creatures get used to it. That means the camera needs to have a long life power supply, and probably a remote controlled way of turning it on and off when submersed in the pond water.

If you have any experience with pond cams or underwater photography in general please can you help us out a little here in the comments?

Miniature or Dwarf water Llilies are a favorite for small water gardeners because they bloom profusely and add a pretty accent to the edge or when placed in the middle of a shallow pond or small water garden feature. There are now several varieties of miniature water lilies available in aquatic plant centres. All will need full sunshine and can be grown in small ponds down to about a foot and a half i depth. Their pads and flowers are small, only about a third of the size of a normal water lily’s. This makes these water plants especially suited for container water gardens as well as fully sunken small garden ponds.

dwarf water lilies for small garden ponds

The centre is golden and the leaves or lily pads are quite large but don’t tend to overcrowd the small pond with a little maintenance.

The variety of water lily is essential to determine before planting, and this one is probably Nymphaea “Amabilis”

Water lily in small pond

Ideally there would be such a large reservoir of rainwater collected from a big roof area into huge storage containers that tap water would never be necessary, but that isn’t practical with the setup I have here at the moment. Rainwater is generally preferable to tap water because the tap water contains a background level of nitrate which is not good for the animal and small insect life in the pond, also the PH of tap water is treated to be less corrosive to pipework whereas the pond life is happier, I think, with the slightly more acidic rainwater.

Not only that but also tap water has been expensively treated to make it suitable as drinking water for humans. Its really a waste to use it for other purposes unless absolutely necessary.

Another way to cut down on the need to top up any small pond is to cut back the vegetation somewhat. Water irises once they have flowered can be taken right back to near the surface level, although then you will miss out on the spectacular seed heads.

Irises in the small pond - cut back to save water?

floating Plant White Flower

The leaves look a bit like buttercup and the flowers stick out of the water on short stems, white with a small yellow centre. It’s not frogbit.

I’ll be able to post a close up picture of the sample of this plant in my own small pond later.