Wednesday, 30 January 2013

Ponds Part 3 - Plants

We showed why we believe that everyone should have a pond and how anyone can make such a feature in their own back yard in the previous parts to this series. This time I would like to give you a few ideas on what to plant around as well as into your pond. The plants I mention here are by no means a complete list, nor are they essential.

Aquatic plants

Aquatic plants are plants that live all or most of their lives in water. Some are sitting at the edge of the pond and dip their roots into the water just at the bank, some are completely submerged and others float around on top of the surface. Before I start mentioning individual plants I would like to say that there is no such thing as an invasive plant. There are opportunistic plants and some of them might be unwanted, but just because we don't want them in our pond does not make them a pest. I think people automatically label anything that isn't deliberatly put at its place in the garden as a pest. According to one of my neighbours, nearly everything is a pest. Bedstraw, alders, dogwood, you name it, it's a pest....apparently. Of course that is nonsense.To show you what I mean I will start with a very common water plant, that is often seen as an invasive pest, the common duckweed.

Pic 1 Duckweed Lemnoideae sp.
Duckweed floats on top of the water and multiplies with an extreme speed. Once it takes hold, it can completely cover the surface area of your pond within mere days. A lot of the time, much to the demise of the owner of the pond. But here is why you shouldn't be upset about it. Duckweed is both an indicator of contaminated water and a cleaner. A clear and healthy pond does not support the growth of duckweed due to the lack in necessary nutrients. Duckweed is often found in still waters that are influenced by pollution. The good thing about it, as I mentioned is that the duckweed feeds on the origin of the pollution and in doing so, can remove unwanted chemicals (I use the term in it's actual sense, not as something describing man-made pollution). If those chemicals are not replaced, by continuous pollution for example, the pond will get cleaner and in time the duckweed will recede as there is nothing left to feed on, leaving organic matter behind to fuel the system. So as you can see this "pest" is actually quite useful and I have heard of constructed wetlands that utilise duckweed to clean the water.

If you really don't like the look of the duckweed and would rather get rid of it, you can simply scoop it off the surface using a large net and use it as mulch or compost. This counts for any aquatic plants by the way. The production of biomass is so high in the aquatic environment that you will, sooner or later, have to resort to the removal of some plants and using them as fertiliser is the best way to deal with the "problem".

Aquatic plants, including submerged, produce oxygen during the day by converting dissolved CO2 and water into energy and O2 just like our terrestrial plants do. This is how water is oxygenated in the natural systems and how the plants help support fish and other animals to live in the water. So even though you don't see a lot of the the submersible plants as they are often completely submerged, it really helps keep your pond healthy to introduce a certain amount of them. One of those plants is Elodea canadensis also called Pondweed. The only time you can see anything of this plant on the surface is when it is flowering. It has a tiny white flower that is attached to a fine thread connecting it with the rest of the plant.

Pic 2 Elodea sp.
There are numerous plants that produce high amounts of oxygen and those are the plants that you should establish in your pond in the beginning, BEFORE stocking any fish. But I will probably write another post on how to stock fish into your pond later.

Then of course there are the surface living plants. The most commonly known would be the water lilies (Nymphaeaceae sp.). I don't think I have to explain much about water lilies. I never met anyone who didn't know a water lily when they saw one and I also never met anyone who didn't like the look of water lilies (although I am sure there are some people). Water lilies are also very efficient in cleaning your water. I haven't got any water lilies in my pond yet. The reason being that I found them far to expensive to buy (our local garden center sells them for $40 a piece. and they weren't in good condition). There is a lake that I frequently visit during the fishing season, which has a lot of water lilies, but you wouldn't believe how hard it is to unearth one of those buggers.

At this stage I would have to put out a disclaimer. BE VERY CAREFUL WHEN TAKING AQUATIC PLANTS FROM THE WILD!

First of all you can introduce diseases and parasites into your pond which is bad in any case. But if you decide to take wild plants please make sure that they are not an endangered species and that you don't cause any irreparable damage to the ecosystem you are removing the plants from. I love Jack-in-the-pulpits and really wanted some for my pond. During a fishing trip I came across a truly amazing specimen which was at least 60 cm in diameter. But the population of those plants are in decline and they are better left where they are. I bought mine from a wonderful person who lives in the city close to us and specialises in native and endangered plants ( So please be responsible about taking wild plants. 

Another aquatic plant that actually volunteered itself in our pond is pickerel weed. Pickerel weed is very prominent around New Brunswick. I am not sure yet, whether pickerel weed might become a problem in our pond. Judging from the speed it took hold it might become necessary to remove it at some point. But it does look nice and for now it is restrained to the edge where the water is shallow. 

Edge plants

Along the edge of the pond is where the biomass accumulation becomes most apparent. Here you can see all the plants that are competing for space and form symbiosis with each other. 

I already mentioned the Jack-in-the-pulpit plant. Jack-in-the-pulpit is a carnivorous plant and a kind of pitcher plant. It has pitcher-like leaf formations that contain a liquid that attracts insects. When an insect lands on the slippery leaf it often falls into the liquid and is unable to get back out. The liquid is actually the digestive juice of the plant and the trapped insects are slowly digested to nourish the plant. The upside for us humans of course are less bugs (less mosquitoes, yesssss....). Although I think our native frog population does most of that work already. But I will discuss the fauna diversity of the pond in the next post.

We also brought in some water cress which has really nice white small flowers and grows all around a large part of the banks by now. Water cress is edible, although I have not yet tried it.

Pic 3 Water cress Nasturtium officinalis
We also introduced American Sweet Flag (Acorus americanus). Sweetflag is a native plant with edible fruits that look quite phallus-like. Again, I haven't tried them yet. Care should be taken when eating Sweet Flag. Some strains produce a procarcinogenic compound called beta-asarone. The strains native to North America though seem to be void of this compound.  Be also careful not to confuse this plant with the very similar looking Blue Flag. As usual, when it comes to eating plants from the garden or the wild, don't eat anything that you can't 100% identify.
Both Blue Flag and Sweet Flag belong to the sedges or rushes. In general those plants have a tremendous ability to clean the water they contact with their roots. Rushes are in fact so good at cleaning water that they are heavily used in constructed wetlands for water purification purposes. Depending on the resting time of the water, a combination of rushes and charcoal can turn even black water into something that is fit for consumption. In order to do this properly you really need to know what you are doing. Constructed wetlands are a complete topic on their own and I might start a series about how to construct one later. The internet is also full of information about those features.

As mentioned in part 2 of this series we have a lot of bullrushes and cattails in the area where we dug the pond and those plants are still very very prominent. I recall a lecture from Bill Mollison, the founder of Permaculture, where he urges anyone to get rid of any cattails along the pond. This is due to the enormous opportunistic properties of the plant. But for now I leave them be. And the fresh shoots taste and smell a lot like cucumber. In fact every part of the cat tail is edible at different times of the year.

Pic 4 Cattail with seedpod opened
There are many plants I still want to incorporate into the system. Water is the best biomass accumulator and some of the fastest growing plants are aquatic plants. While plants like kang kong (Ipomoea aquatica, aka water spinach) do not grow in our climate, other edibles do. One candidate high on my list is water chestnut. The production of edible nuts is supposed to be very prolific. 

Surrounding the pond

Going a little bit further away from the pond's edge is where we started to plant several other shrubs and trees. On the northside of the pond (which is the start of the slope we built with the excess dirt described in part 2) we planted a plum and a cherry tree. Both of those trees are cold-hardy types and they should be able to cope with the winters here

Pic 5 Afton planting our Cherry tree (Montmorency)

A pond or lake can be utilised to extend your growing season for fruit bearing trees and bushes. The large amount of water acts as a heat sink (in the hot times) and as a sun reflector (meaning the suns rays have a stronger affect in the cold times). Sepp Holzer, a Permaculture farmer in Austria, has created multiple microclimates using ponds at his farm, that allow him to even grow citrus fruits at altitudes higher than 1,000 m above sea level.

Furthermore, around the pond we planted blueberry, blackberry, raspberry and haskap berry bushes that all benefit from both the constant supply of water and the additional climate buffering properties of the pond and we benefit from the healthy and delicious fruits and berries that these plants produce. Win-win I say.

As I said before, there are so many plants you can incorporate into your pond and it helps to read up on them all to see how you can build guilds of plants that interact positively with each other and their environment.  So let your imagination run free and happy planting.

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