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On a Chalk Hillside December 2018

Making a Bog Garden

When we created the terrace for the pond, you may remember we also created a space down one side that was to be the bog garden, with a separate Gunnera manicata bed below it, but attached.  Here is a picture showing the bog garden with the bench on it, the boarded out gunnera bed, the start of the steps down the side of the pond, and the path in front of the pond which the wheelbarrow is on.  As you can see both the bog garden and gunnera bed were completely infested with dandelions, (with roots at least a meter deep in some cases as we discovered when we excavated):-

In order to retain water in our light chalk soil the bog garden was excavated of soil to a depth of about 50cm and then pieces of butyl liner left over from making the pond were put in (with a few holes in for drainage).  We then riddled the soil to remove flints and stones – an extremely laborious process!   Here is a shot showing the gradual filling of the bog garden with soil, and the first plant - Rodgersia Aesculifolia ‘Irish Bronze’:-

(A quick aside to say that there is an overflow built into the wall between the pond and the bog garden so if the pond gets too full of rainwater it can run away into the bog garden.)  
From the state of the plants in the above picture you may be able to tell its late September!  Here is a shot showing the first plants going in:-

I am putting in some drumstick primulas (Primula denticulata) beside the Rodgersia, with Iris foetidissima behind it.  The large tray of plants beside the washing up bowl is Soleirolia soleirolii ‘Aurea’ – golden Angels tears which I had propagated up to be ground cover to help minimise moisture loss in the bog garden whilst the plants were small.   The plant you can’t see already planted just the other side of the Iris is Astilboides tabularis, formerly Rodgersia tabularis.  Here it is coming out the next April with some of the primula in front and the Soleirolia  soleirolii ‘Aurea’ around it:-

The Iris has expanded enormously, and its fabulous seeds come out in the autumn and were still shining bright in April this year:-

As you can see, to begin with the Rodgersia Aesculifolia ‘Irish Bronze’ doesn’t overshadow the Iris as its new leaves unfurl in early April: – 

But by early May, the Iris is hidden away behind the fabulous leaves of the two rodgersias:-

The leaves on both Rodgersias are large and impressive, with the big round lime green leaves of Astilboides tabularis, formerly Rodgersia tabularis being up to 45cm across.  These do fade to a duller green as the summer progresses, but in April and May are a great foil for the bronze tinge of the Rodgersia Aesculifolia ‘Irish Bronze’ and the burgundy leaves of the Lysimachia ciliata ‘Firecracker’, as you can see below, with Geranium macrorrhizum ‘Ingwersen’s Variety’ flowering in the bog garden on 10 May this year:-

I love this colour combination, and the bog garden continues the bronze tinge in spring with a continuously spreading clump of Water Avens (Geum rivale) at the end of the bog garden that abuts the Gunnera bed. 
Here a Tree Bumblebee (Bombus hypnorum) is gathering nectar from the Geum rivale flowers towards the end of May:-

To show you the lime/yellow/bronze theme, here is a shot across the pond to the bog garden at the beginning of May this year with the Caltha palustris (Marsh Marigold) flowering in the pond, accentuating the foliage plants in the bog garden:-

Hard to believe that by June the Rodgersias leaves have faded to this:-

As you know, later in the season the Lysimachia ciliata ‘Firecracker’ has small yellow flowers over a long period, and, to reinforce the vision of spikes of small yellow flowers, I also planted Ligularia dentata ‘The Rocket’.  Twice.  It got as far as leaves once, but the slugs loved it with such abandon that it never survived to flowering:-

I also planted Lythrum salicaria (Purple Loosestrife) at the far end to the Rodgersias, at the gunnera bed end for its purple spike of flowers later in the year.  

Above, in later June last year it is in flower, but its spikes continue all summer, and is still in full flower in August – below from 2016 with a Common Darter dragonfly using it as a perch to watch for insects, with the Gunnera leaf in the background:-

Once I finally gave up on the Ligularia, I planted a Crocosmia 'Lucifer' instead for later summer flowering.  This is very short lived in the bog garden – some winters I expect are just too wet for it to survive as it needs moist but well drained soil.  I am lucky I had a quite good supply of this plant from my Step Mother’s garden after she heard a specialist nurseryman speak at her South Penines Hardy Plants Society Group meeting.  He told the group that Crocosmia 'Lucifer' (and I assume other crocosmias) need to be dug up every few years as they make new corms on top of their existing corms year on year and gradually raise out of the ground and fall forward.  So she dug all hers up and retained the parts of the chain of corms she wanted, and put the rest in a big bag for me.  Obviously some parts of the chain of corms were old and deceased, but I lined out in my nursery bed parts that I thought were viable, and once I could see new leaves growing transplanted some into the bog garden.  As it gets to 1.2m high, and flowers in August and September this is a good late summer splash of colour in the bog garden:-

For even later colour I planted a Toad Lily, Tricyrtis hirta.  Here it is flowering in the bog garden that very first October:-

It struggles a bit as it is in more sun than it would like, but is shaded by the Rodgersia for much of the earlier summer.  What an exotic and beautiful flower for October.  
Most of the plants that my husband likes best of all are architectural ones with big leaves.  Ever since we had visited the ravine gardens in Cornwall full of Gunnera manicata so huge you could walk underneath them, their roots in the running streams, he had hankered after one.  My sister eventually offered him her plant – a tired, miserable specimen in a dustbin sunk into a shady bed in her Sheffield garden which on excavating we discovered had “walked” and was trying to escape into the wider garden.  It came home with us in an empty multipurpose compost sack, and was heeled into the bed near the house (as it was the only one in the shade some of the day) still in the sack, which had a few holes punched in it.  It hung on for a couple of years in this situation until we had created the bog garden to plant it in.  
We created a separate bed for the gunnera, dug to more than a meter depth to take account of the amazing long fleshy roots of the gunnera.  Here’s a shot of the lining/sieved soil as with the bog garden:-

Here’s a shot showing the gunnera planted:-

Gunnera originated about 150 million years ago at the very beginning of the Cretateous period – a mere babe compared to the Equisetum and dragonflies I mentioned in my article about the marginal planting in the pond, but still from the times of the dinosaurs.  In all the years planted here I have never yet managed to get a photo of a dragonfly actually ON the gunnera, though as above, it is a backdrop.  Although Gunnera manicata comes from South America and needs to be in damp conditions, covering the crown with its own leaves (or fleece) seems to be sufficient in this garden to help it survive through the winters here, even if the ground freezes.  This is one tough plant, no wonder it has survived from the Jurassic era, and is thought to be over 150million years old.  However, whilst it does get very big, it is in full sun, and whilst it hangs over the paths all round it, you would have to limbo to get under it rather than stroll as we romantically envisioned.  
I quickly discovered that the larger leaved plants overwhelmed the drumstick primula in the bog garden, and so planted some under the gunnera instead.  However, having to leave the gunnera covered until at least late April meant the primula leaves came up underneath and got yellowed, and lacked nutrients, so we created a separate tiny bog garden bed at the other end of the pond opposite the gunnera to put small bog beauties in.  

This has variously had four different drumstick primula, including seedlings from a packet of mixed seed from the HPS seed distribution scheme which you may be able to see in the photo above; several different candelabra primula (such as Primula japonica ‘Miller’s Crimson’); Primula florindae - Giant Himalayan cowslip; and ragged robin, both the native Lychnis flos-cuculi, and a white form, Lychnis flos-cuculi ‘White Robin’, planted round the outside of a clump of Astrantia ‘Buckland’.  Only the astrantia has survived year on year.  The others all cope for a year or so and then fade away.  I feel the bed is too small, and too sunny to stay successfully damp enough for these other plants.    Here is the Primula japonica ‘Miller’s Crimson’ doing its best in May 16:-

I was particularly keen to have the Giant Himalayan Cowslip (Primula florindae) as it is fragrant, flowers for several months in summer and can get over a metre tall.  The pond and the bog garden is just below my Cowslip meadow under the pear trees you may remember me writing about previously, and I thought it would be a nice nod to it to have this plant follow on from the Primula veris.  

Well, though it has an AGM, it clearly doesn’t like my more alkaline than acid soil, the sun and the drying out of the little bed.  It only flowered the one year, making a rosette of leaves the following one, and then giving up entirely after that.  
Next time, that fun winter job – pond maintenance.

Sheila May

Posted by Sheila May

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