Green Roof – early spring 2017

The vivid lime-green of Euphorbia myrsinites and violet grape hyacinth are creating a striking patch of colour on the green roof right now.

The Euphorbia was only added last summer, so it is good to see it settling in happily. I am aware it can get rather large, so am hoping that the exposed situation and shallow soil (7cm) on the green roof will stop it getting too bit. Its spiky glaucous leaves look good here too. Continue reading

Pasqueflowers re-bloom in August

Purple pasque flowers unexpectedly emerge for a second flush in August

Pasqueflower, Easter flower or Meadow Anemone (Pulsatilla vulgaris), is one of my favourite plants. Almost every stage of its flowering is interesting:  The large flower heads emerge in spring (close to Easter) along with the foliage, all of which is covered in fine silky hairs, and look striking especially when backlit by low spring sunshine. Continue reading

The Green Roof: lessons from the first five years

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This is a visual catalogue of how my green-roof developed over its first five years, following its initial planting in Autumn 2009. My intention had always been to establish a low maintenance bio diverse plant community of drought tolerant garden plants. I now know that this is possible, but looks more like a weedy wild meadow than a garden.

This initial experiment was a success in many ways, as the beautiful photos below show, but by mid-2015 it’s ecological direction was clear: self seeding grasses and annual weeds were destined to win. More than half of the plants varieties I had tried to grow became extinct. Several garden varieties I had not planted turned up and ran riot. The whole area was becoming a seed bank that was infecting the surrounding garden. But I had learned some important lessons and had enjoyed its unfolding beauty along the way. Continue reading

Green roof bulbs triumph

Nothing helps shorten the seemingly interminable English winter more than early spring bulbs – bright and hopeful in the brief moments of sunlight that pierce our typical grey skies.  In this regard the green roof has proved itself unexpectedly successful, and created a fantastic display (of which the above is just a tiny portion) far earlier in the year than I expected.

Following a long dry summer and one of the coldest winters I have known these purple Iris reticulata and cream Crocus have made a triumphal return, far bolder and brasher than the snowdrops that have only just opened in the woodland garden. When I planted this rooftop experiment some 12 months ago I was unsure how well they would do – there was scant information on the web of other green roof gardeners having planted these bulbs, or any bulbs for that matter.  Where I have planted Iris reticulata and crocus sp. in other areas of my garden they have never returned with such vigour – in fact they usually fade away rapidly, with a high percentage coming up blind in their second year. Here on the roof, though, they have come up strong and full of buds! I had guessed the environment of the green roof might mimic their native habitat and thought that a good summer baking would help ripen the bulbs. It would seem from these promising early results that they may, indeed, turn out to be perfect green roof citizens.

The mossy mounds in the photo are of interest too. Those in the foreground are small hummocks I plucked from the tiles of our house roof last year. After placing them on the green roof they sulked, and quickly turned brown as the summer came on. However, having somehow survived the pigeons that scavenged them for nesting material, and after spending a week or two covered with a foot of snow, they have rejuvenated and are now starting to form a happy green carpet (I hope!).

The large mossy mound in the midground is not a moss: it is the Falkland island Balsam bog or Cushion plant (Bolax gummifera) – unlike the moss this stays a fresh green all year round, and is quite firm, even hard to the touch, so the pigeons give up on it tout-suite . Like the other plants in this post it was something of an experiment – I didn’t know how it would cope with summer drought and winter wet – but like the bulbs and true moss it appears to be quite a success as a green roof moss mimic.

Gallery of triumfal bulbs:

The Green Roof – in June

Here is a view across part of the green roof, showing how far it has come on since my last Green Roof update. The plants have become establishes, and I have added many new plants which are all thriving in just 7 to 13cm of soil, with only occasional watering – once or twice per month – to help them through their first year.

The secret of success in these situations is to choose plants that grow naturally in hot, dry, exposed situations. In the above picture, middle, foreground you can see  Lampranthus cooperi – a half-hardy Mesembryanthemum relative with succulent foliage and bright magenta daisy flowers (which are closed up in the photo). It loves these conditions, although it may struggle to make it through a wet British winter – we will see.

The seed heads here are from the Muscari bulbs that finished a while ago. Top left is a new addition –Dianthus deltoides ‘flashing lights’ – many small dark red flowers over dense dark green (almost black) foliage. In the bottom right corner you can see some crimson stonecrop (Sedum spurium ‘Coccineum’)

Here, biting stonecrop (Sedum acre) is colonising a bare patch of gravely soil. Small fragments dislodged by birds probably, have rooted and started to grow. The main clumps are about to come into flower.

Dianthus ‘Flashing lights’, surrounded by the grey blades of Festuca glauca.

The pink lollipop flowers of thrift do so well in this situation – flowering for weeks on end. The grass to the left is Ponytail grass (stipa tenuissima) with very fine tall blades, held upright, but not stiffly, catching the slightest breeze. The inflorescence is equally delicate, transparent, like a veil.

An experiment that is proving highly successful: On the left – a fern polypodium vulgare, and on the left, golden Creeping Jenny (Lysimachia nummulariaAurea‘). Both of these plants tend to be associated with damp shade, but both are just fine in the extreme conditions of the roof-garden it seems. I have seen our native polypody fern as an epiphyte on old oak trees in Devon, colonising dry stone walls in Wales, and covering the top of the high stone walls of the ruined Abbey at Winchelsea – exposed, dry and sun-baked. So I shouldn’t be surprised to see the five clumps on my green roof putting out new fronds quite happily.

Three recently added plants, left to right: Silver shamrock (Oxalis adenophylla) – blue-green pleated foliage and transparent pink flowers in May; Sedum spathulifolium ‘Cape Blanco’ silver-grey succulent clumps; A red Houseleek (Sempervivum var.) – which is spreading rapidly – it likes the sun and exposed aspect.

The Green Roof – two months after planting

Only a couple of months after planting and the thrift is in flower. The Ice plants (Sedum spectabile) are fleshing out into stocky clumps with their old seed heads still providing textural interest and contrast. The clump of pale green grass in the mid-right foreground is Carex ‘Evergold’, to the far left Festuca glauca. The seed heads towards the top are from the white Pasque flower (pulsatilla vulgaris  ‘Alba’) which I added a few weeks ago.

This closeup shows rain drops clinging to the ponytail grass (Stipa tenuissima). This grass has such a fine blade, standing upright and flowering with delicate golden heads in a month or two. Its downside is that it seeds like crazy – so I may regret introducing it to the roof!

Notable in this view is the candy pink flowers of alpine catchfly (Lychnis alpina) with its bright green tufty clump of foliage and the mound of purple stonecrop (Sedum spathulifolium purpureum). I am pleased with how quickly the plants are creating an alpine meadow effect.