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On a Chalk Hillside August 2018

Constructing a pond – water plants

I know I mentioned the weather last month, but we have had no rain in July bar a day of windy drizzle towards the end, after none in June.  The muggy heat in May that turned into serious heat in June and an actual heatwave in July has really caused the garden to suffer, particularly as we only water the vegetables and plants in pots.   It is a struggle to keep the vegetables hydrated enough to survive, but so far the only crop that is thriving in the heat is the courgettes.   The raspberries were early, small, and dry.  After I picked the first ripe ones the next flush simply dessicated on the plants without ripening.  Our soil is like dust, and to a depth of at least 30cm, so it is a mystery to me how the shrubs can stay alive in such circumstances.  I have lost many plants in pots that I have simply not been able to water often enough to survive.  We have had to top up the pond several times as the water level goes down from several causes - all the wildlife come to drink from it and bathe in it as well as water loss from evaporation and the plant life in the pond.  We try to top up with rain water to minimise disruption to the pond water ecosystem, but the waterbutts are not getting refilled.  Enough complaining, let's turn back to creating the pond.
In order to determine how deep to dig the pond we needed to determine what plants we wanted in the pond.  Naturally our first thoughts were of water lilies.  This was a bigger pond than we had had before, so we could have a more expansive water lily.  This meant the pond needed to be about 1m deep.  This took SOME EFFORT.  In fact it was very difficult, as the hole shape and size meant that spades couldn’t be freely wielded, or indeed pick axes to loosen the soil for shoveling out.  Soil had to be shifted into buckets and then carried to wheelbarrows and barrowed to the storage bags in the orchard. Slow and hard work.  
Here is the hole and buckets:-

You may notice a couple of wooden pegs in the ground roughly opposite each other sticking about 15cm out of the soil?  The top of those pegs represents the intended water level.  The next stage was to put some carpet in the bottom to help protect against those flints you can see:-

  Then underlay, (Don’t worry we filled in the gap!):-

Then we had a jolly good wrestle with the butyl liner.  An enormous piece of butyl that it really does pay to lay on a warm day – it is so much more pliable if you do.  Here are some wrestling shots (obviously most of the time it involved both of us manoevering, so this is mainly later stages) where we tried to smooth out the wrinkles as much as possible by using the weight of the water to help:-

When thinking about water plants it seems there are three different “zones” with different plants in each for the pond – floating, submerged and planted.  You also need to take into account oxygenation of the pond.  If you are having a still pond (as we were) you are reliant on plants to oxygenate the water rather than the moving water.   As I considered different plants I also checked whether they helped oxygenate.  So naturally the very first water plant that went in was Canadian pond weed Elodea canadensis to aid with oxygenating (a submerged plant). The second was Water Soldier Stratiotes aloides. This is a floating plant, which you just chuck in – see below:-

Stratiotes aloides is a great plant, very hardy, evergreen, and is a good indicator for me of the seasons as it sinks below the water in autumn and comes back up for its leaves to break the water surface in spring.  It even has little white flowers.   Here it is emerging in June 2016:-

And here is a shot of it flowering in June 2017:-

This illustrates that it is water temperature rather than just day length that affects when the Water Soldiers rise up, as the second shot is from the 2 June 2017 (with blanket weed suddenly blooming in the warmer water as well as the Water Soldiers in flower) whilst the first one was taken on 7 June 2016 and the plants are just beginning to emerge – a good two weeks behind horticulturally.   Here is a closer shot of the flower:-

Another floating plant I wanted was Frogbit – Hydrocharis morsus-ranae.  Beguilded by the description – it looks like a baby water lily with three petalled white flower – how could I resist, and it is an oxygenator, and native to Britain.

 I believe I still have it in the pond – I have chucked bits in twice now, but whilst I see the leaves occasionally I think the Water Soldiers are preventing it spreading much.
In terms of other oxygenators I was on the look-out for Water milfoil – Myriophyllum verticillatum which particularly likes alkaline water, and although a submerged plant put feathery stems above water.  I visited a yellow book garden just as we were completing the construction of the pond and the owner had a completely circular pond reflecting the clouds with a 15cm collar of Water milfoil round it.  I asked questions.  The very generous owner reached in a pulled me out a clump from her pond.  She had hers rooted in soil at the edge of the pond, and indeed my book said Parrots Feather could be propagated by cuttings pulled off in the spring and rooted into submerged mud.  So I divided the clump I’d been given and poked bits into the soil on the marginal shelf.   I believe now that the plant I have is Myriophyllum aquaticum, as its stems are very red, and if we have a harsh winter when the pond freezes over it dies down to a crown in the water.  For a couple of winters after the pond was made this is the sort of winter we had, and it grew well but not too rampantly.  Then we had mild winters, and it took hold and went wild.  I pull out armfuls of this at least twice a year when there is less risk of tadpoles or damsel and dragonfly eggs being on it.  The newts love it and hide under its mat and lay their eggs there.   It is the most beautiful plant, has a lovely reddish coppery tinge to it at times, but it is so deeply rooted into the soil of the margins I cannot dislodge it, only contain it.   Here it is on 11 June 2015 as a back drop to some red Damselflies sitting on a Water Soldier leaf:-

You can probably see in the above photo another of my floating plants – duck weed (Lemna minor).  I promise I didn’t plant this, and indeed for many years we didn’t have any, but some passing bird must have come for a drink or a wash and left us this present.  Now, I shall quote Stefan Buczacki who has a soft spot for duck weed - “As a child it was because of the pleasure I gained from seeing frogs poking their heads through its light green, all embracing carpet.  Since, I have admired it botanically as one of the smallest of all flowering plants, with each tiny frond or thallus being a complete individual.”  Hmmn he does also admit it spreads a lot, and that once you’ve got it, you’ve got it.  So it is another plant that gets removed regularly.  On the plus side, it is covering the surface of the water which does help to keep the blanket weed down.  
In terms of plants planted in the depths of the pond, initially there were two:-  Pontederia cordata – Pickerel weed - to give blue flowers late in the summer, and Water Hawthorn – Aponogeton distachyos.
I expect you are all au fait with pictures of TV gardeners in waders carefully stepping into their ponds and lifting in or out aquatic pots of plants.  If you think of our shape of hole, this is not much of a goer – so this is how we attempted to plant the pickerel weed…..
As you may recall I said the pond was 1m deep.  Pontederia cordata likes to be in water no deeper than 30cm.  So its planting pot needed to be raised off the base of the pond by about 50cm.  Our low tech solution (which is still working currently) was to weight down a builders' bucket with sections of breezeblock inside it, so that a second builders' bucket could sit in it level, filled with breezeblock bits and finished off with aquatic grit for the actual aquatic plant pot to sit on.   Somehow, my husband managed to lower these in without my having to sit on his legs, AND without falling into the pond!  First bucket goes in:-

Second bucket goes in on top of first:-

Pickerel Weed positioned:-

 At the other end of the pond I put in Water Hawthorn, Aponogeton distachyos, such a favourite plant of mine.  It can cope with depths of around 60cm, so was planted in the top of a builders' bucket and lowered in. Its flowers, which are scented, break the water’s surface early and late in the year.  Here it is in flower just after it was put into the pond at the beginning of November 2009:-

And here it is in May this year in fine fettle:-

From mid-June 2013 here is a shot across the pond to show reflections of the sky, and how the planting had developed:-

By mid-July you wonder where the pond is – see here in 2015:-

By September, the Pickerel weed, Pontederia cordata, is coming into flower against the autumnal hues of the rest of the pond plants:-

Although this year in the drought and the heat, along with many other plants flowering or fruiting early, here it is in flower on 11 July:-

And here is a close up of the flower:-

By the way, have you noticed – no waterlily?  We are still thinking about which one, and whether all the wildlife will like it!!


Sheila May

Posted by Sheila May

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