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Running rings around irises

Gardening inspiration can come from the most unlikely sources. Here, firmly in Devon clay, parts of an award-winning roof garden from an RHS flower show are reborn - using concrete drainage pipes!

Royal Bank of Canada Show Garden, RHS Chelsea Flower Show 2013A couple of weeks ago I finally got round to tackling a job that has been on the list ever since the Chelsea Flower Show 2013. Our esteemed curator came back from the show that year inspired by a design and practical solution he’d seen in the Royal Bank of Canada show garden for keeping two vigorous types of iris, the yellow flag (Iris pseudacorus) and Japanese (I. laevigata) separated in water gardens.

Miriam 'manhandling' one of the ringsI would not say I had been putting off this task, just considering all the permutations to avoid any disasters. In order to keep costs down we came up with the idea of cutting concrete culvert pipes into sections to create the desired rings. I investigated the various options and in the end it was decided to opt for reinforced concrete to ensure enough strength is maintained in the cut pieces.

It took some manoeuvring to avoid the bridgeOf course, being fibre reinforced concrete means it’s tough stuff, so cutting through it was a mission; but with a team effort and quite a few diamond-encrusted discs, we got there in the end.

Unfortunately though, the larger of the pipe diameters I ordered is thicker than the depth of our saw blade, so we hastily brainstormed the idea to drill through the remaining uncut depth every six inches, then whack between the holes from inside the pipe with lump hammer and bolster until the sections crack apart. Thankfully it worked, and I was in the clear!

Job well done! Miriam and Jonathan by an installed ringThe next mission was to crane the rings sections into the ponds and get them set in, as you can see by the pictures in was an exciting day, and given a few months to bed in, and once the irises have got going in their new circular homes we are hoping they will be as much of an architectural statement and practical solution as those at Chelsea.

The rings planted with irises

Useful links

See what's coming up at this year's RHS Chelsea Flower Show

Get RHS advice on growing pond plants


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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.