Bog gardening – again

On the grounds that if you are going to get wet, you might as well get muddy, I’ve been working in the teeming rain on the bog garden by the pond. Given the amount of rain the British Isles have had this summer, I imagine a few people may be contemplating starting a bog garden. So I thought I’d go back to a few first principles – learned through hard experience. If you also want a professional gardener’s guidance (plus an excellent plant list) I thoroughly recommend Beth Chatto’s ‘The Damp Garden’ – a book that helped me hugely when I was starting to learn about bogs.

Drainage.

It’s no good just finding a wet patch and sticking plants into it. It’s important to know where the water is coming from, where it is going to, and whether there is any flow through the soil. Plants will die if their roots hit the anaerobic environment of stagnant water.

Other than the purely aquatic ones, only a few plants will tolerate waterlogging for any length of time. The primulas here regularly get flooded, but there’s a drain to one side, so the surface water soon disappears. Ideally, you want the water table to be around about a foot (50/60 cms)  beneath the soil surface.

The quickest way to explore what the water is doing beneath your boggy patch is to dig a hole, watch how quickly it fills, whether the level varies much, and whether the soil at the bottom remains damp during a dry spell. Fill the hole to the brim with a bucket of water and see how fast it sinks back to the previous level. If it lingers longer than  few hours, you probably need to improve the drainage. Here’s a place (it’s supposed to be a path)  where a new drain is definitely needed:

If it’s not clear where your water is flowing to, one solution is to create a soakaway at the lowest point of your bog. Dig as deep a hole as you can manage, drop in a layer of rubble, and then fill it with gravel. Then direct your drainage into it. I always leave my drains open. In my experience, no terra cotta or plastic pipe can cope with very fine clay silt or with primula roots, and digging up buried drains is a far worse task than clearing open ones. I dealt with constructing an open drain here, and in subsequent posts, and I’m at work leading further seepage directly into it.

Access

You need to be able to get to the interior of your bog garden without sinking into the ooze, especially if you take a wheelbarrow. Compacting damp soil by treading on it constantly does no one any favours. So a path of some hard material is probably needed, preferably stones or bricks – on end – .Gravel just sinks into the mud, and if you use slabs and drop one in the wrong place on sticky clay, it’s the devil’s own job to shift it. From an aesthetic standpoint, your path should appear to have (or have had) a function other than just leading you into a bog. I try to disguise mine as a rock shelf.

Plants

Weeding a bog garden is the pits, and to be avoided at all costs. This means choosing plants which are big enough to dominate buttercups and other damp-loving weeds. It also means avoiding small damp-loving plants. This is a sacrifice, but believe me, in the long term, you won’t regret it.  Your plants may look nice and manageable in Spring, but by August you will be deep in the wet foliage trying to save your prize specimens from the rampant jungle. Big is best. And, iIf you have enough space for it, gunnera tinctoria takes on everything around it and wins.

Otherwise, I rely on the ligularia and inula families, plus the big rogersiasand tough, rampant hostas. Iris too, of course. Even the semi-wild montbretia, crocosmia x crocosmiflora is happy in a wet soil and forms huge clumps that suppress any intruders. More refined crocosmia cultivars aren’t robust enough .
But of course, the star of my bog garden, seeding itself everywhere, and totally weed-proof  is primula florindae, just now coming into the full glory of its flowering, its heady perfume at its best in the rain.

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17 thoughts on “Bog gardening – again

  1. The quality of light in that final photo is stunning – particularly given that it is raining (again / still). But “…….tough, rampant hostas”? Aren’t your Scottish snails even tougher and more rampant?

    • Minety, I make to claims to understand the mind of the gastropod, but for some reason neither slug nor snail ever touches my hostas. Perhaps they have never learned from their neighbours? Ligularia OTOH need constant protection. Yes, I was pleased with the light in that last shot – pity the primula was out of focus!

  2. So remarkable, all that water. A gunnera died of drought here once. Nice rocks (always) and lovely primula. I’ve never known the fragrance…

    You could use some ferns.

    • I think it’s too wet even for ferns. One day, someone will digitise fragrances, and then we’ll have a scratch ‘n sniff internet….
      What the bog garden now needs is a hummingbird or two.

  3. Great post – I wish I’d read this before starting my Soggy Bottom border. It’s not quite a bog garden but your post makes me think more preparation might have been in order!

    • Hi Libs, If your damp garden flourishes without the need to dig holes and drains it’s all to the good! It’s only when it comes to ‘why is this plant doing well and why is that one dead?’ that you may need to start investigating…..Hope the florindae are enjoying the rain….mine are, although the slugs are scything away at the flower stems.

  4. ‘The Damp Garden’ is excellent Mr K as is your bog garden. I must re-try with the p. florindae (I think I told you that I managed to kill my one) – the thought of it self seeding about the Priory ponds makes me giddy. Dave

  5. Wow, never knew all that work was needed!! OK, yes the water does drain away, but across the lawn, behind the oak, down past the garage, then out down the road. We found that out when we had a really hot, dry summer, the only year the lawn went brown, except where the underground stream is and that stayed bright emerald green! Beth Chatto’s Damp Garden was one of the first books that I bought when we moved here, so useful. Also enjoying florindae at the moment and as you say, the perfume is wonderful!

    • Hi Pauline. An underground stream sounds wonderfully romantic! I just have broken field drains and dripping rocks. Do you use florindae as a cut flower? I usually fill a large jar with them and try to get the perfume indoors. They last well, but the scent is never quite so intense.

  6. Mr. K., I always visit your blog for the exotic enjoyment of lush, green, large-leafed plants but wish I could find something to say other than, “I don’t think those will grow in the desert.” Pretty sure that’s doubly true of your bog plants. I’ve used the soakaway idea, though, only here it’s more of a (hopeful) soakinto.

    • Hi Stacy, You don’t need to worry – I visit your desert blog for a bit of sunshine and heat, but I’ve got nothing much to say either, other than ‘I don’t think that wil grow in Scotland!’ Different climates, different problems, different longings. Do you have hummingbirds? Linnie, http://linniew.wordpress.com/ has hummingbirds, and I so want some!

      • We do get hummingbirds in summer, though not as many varieties as in the Pacific NW. (On the other hand, we have roadrunners, too.) A pair of black-chinned hummingbirds visits my garden regularly and gets into squabbles with all comers, including the butterflies. I don’t blame you for wanting a few!

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