Horticultural

Green roof update - six months after planting

As years go, this probably wasn't the best for establishing an extensive green roof - too dry by half, and I know I am anthropomorphising but the crows and pigeons seemed to take a vindictive joy in pulling out my plug plants and spreading them around the garden. Nevertheless, things have changed a lot since I first planted it up back in March. It's useful to look back and remember the bare expanse of soil which is now, well, still a bit patchy but there's a lot more green to be seen.

Yesterday I planted out the sedums I'd been growing from seed (using T&M rock garden mixed), and was pleased to see that some of the sedums and sempervivums I planted earlier in the year have established really well. You can also see in the picture to the right some surplus-to requirements Verbascum 'Silver Lining' that I planted up there in some of the deeper areas as an experiment. I am still expecting it to look rather bare in the winter when all the annual wildflowers die back, but I know they've been self-seeding (with a bit of help from me) so there should be a great new flush of grwoth in the spring.

There are some odd things up there - for instance, loads of amaranth* in red and greeny-yellow which I think must have come from one of the rather panic-bought packs of 'meadow mix' I bought when things were looking much barer. There's also some pink cosmos (ditto) and lots of alyssum. Some grasses are getting established (which as Kate Bradbury has pointed out on her recent post on the Guardian gardening blog, are an important thing to include). I've removed some things - fat hen in abundance, couch grass and a few ragwort-type things, but at the moment until the bareness is completly gone, I am letting things take their course.

One of the strange things about the roof as a "garden" is that it's only really visible from my bedroom window, although I do rather like the little line of plant silhouettes  you get when looking up at the roof from the side passageway - just visible in this shot.

There's a full set of photos on Flickr. I would love to be able to identify everything, so do take a look: for instance, what's this little pink flower, above - anyone? My plants for next year are not very strategic - I think it's going to take at least another year to settle down. I'd like more grasses, in the Briza media vein, but would welcome any other suggestions - preferably stuff I can grow from seed.

*I'd like to harvest the amaranth grains - any advice on the best method would be welcome!

 

Side passageway at sunset: what no Nicotiana scent?

I like this shot because not only do the big leaves of the Nicotiana sylvestris look good under the light, you can also see the silhouette of the plants on the green roof at the end.

This part of the garden has been an object lesson in the benefits of "backdoor gardening" - because these beds are literally outside my back door, I spend lots of time tending them. It's also interesting to compare this picture with one of the same scene from May.

The only minus is that the nicotiana smells of precisely nothing: I even got the other half and his rather more sensitive nostrils to confirm my fears for me.

On the wall you can see the second of my "controversial" mirrors - safe to say this one's just about as unpopular as the other. It breaks up the fence screening, though, doesn't it?

One thing: where's all the delicious night-time nicotiana scent I was promised? Perhaps this little cold snap means the scent isn't wafting as it should. Oh, who cares, they look great and I have a terrible sense of smell anyway.

 

On the verge: why my garden can't possibly live up to the delights of the A421

I am not such a great driver right now. Whenever I am on the road, I keep getting distracted by the verges, like this one on the A421 towards Cambridge.

I could bash on about how nature does it so much better than us, but you've probably heard that all before. It is interesting, though, how similar some road verges are to some of the planting at Chelsea this year, as Alys Fowler pointed out to me when I bumped into her at the show. I keep seeing amazing specimens of milk thistles (I think), but not in places I can stop the car!

It's the fullness, the boldness and the sheer exuberance of the poppies lining this drainage ditch that I want to recreate in my own garden. And on my green - by which I mean still mostly brown - roof. I am hoping that through my complete lack of intervention, something wonderful will happen up there and I'll end up with a lovely motorwy verge-style display to be enjoyed from my bedroom window. Perhaps today's rain will get it on its way. Otherwise I shall have to publish a rather ridiculous thing that's been rattling around my head the last few days, a sort of sub-Muddy Waters number entitled "I Got the Green Roof Blues".

Anyhow. Having long since run out of money for new plants for my still yawningly empty beds, I have resorted to sowing lots of perennial seeds, as I have already said. For some reason that's mainly verbascums right now - who knew they were ridiculously easy to grow? Cenolophium denudatum, on the other hand, scorns me. As does Eryngium bourgatii and some unusual clematis from Everett Leeds of the Clematis Society. Humph.

So the verbascums will have to do for the minute, but I am taking inspiration from the Leeds City Council garden at Chelsea, which featured them along with British native fox and cubs or Pilosella aurantiaca. I've already got P. aurantiaca up on the roof, will have to consult the green roof literature and see if the verbascums will have a chance up there, too...

Planting up the green roof

Ever since the garden office was finished I've been panicking about planting up the green roof. What to put up there, will it grow, will it leak, will I fall off the roof? I set aside this morning as 'roof time' and offloaded the kids onto my other half so I could dedicate myself to the task without distraction. And I am delighted to say that I survived the experience without any broken bones and hey, I actually enjoyed it!

When it came to what to plant, I'd originally plumped for a fairly dull sedum matting roof, but after consultations with the wonderful and very helpful green roof expert Dusty Gedge I decided to opt for something a bit more interesting. Dusty's the co-author of a superb guide to green roofs which I'd recommend to anyone wanting to undertake their own domestic green roof project. He advised that providing the roof could take the extra weight (which it could), a mix of sedum and wildflower plugs plus a sowing of annual cornfield flowers was a much cheaper and more diverse option than sedum matting. The idea is that the annuals grow up to provide a temporary riot of colour while the other plants settle in.

The plug plants, prepped and ready to go ...

The technical stuff (scroll down for me clonking myself on the head with a ladder)

The substrate - a special lightweight soil designed for green roofs - had already been applied by my builers at a depth of around 70-100mm, and planted into that are two trays' worth of plugs (a total of 208 plants) from British Wildflower Plants*: the money was running out by this point, so I scrabbled together various sedums from plants I had hanging around the place, rather than buying in sedum plugs, and I also dug up a few things from my gravelly front garden, including fox and cubs, some kind of veronica I, erm, foraged from a crack in a wall a while back and some sempervivums; plus some chives (regular and some unusual white ones) from the veg patch. Then there's annual cornfield seed mix from Just Seeds sown in between the plugs. I fully expect to be tweaking the selection of plants up on the roof, removing anything I don't like and possibly introducing new plants as time goes by. From my research, it seems that the key to picking plants for a green roof is to choose things that can get by in tough conditions, without much soil, moisture or fertiliser - which translates to me as stuff that can grow in the cracks of the pavement - yes to chives and Briza media, no to anything with a deep taproot.

So the complete list of plants up there is as follows:

• Sedum album 'Coral Carpet'
• Another sedum I couldn't find the label for
• Allium schoenoprasum
• Allium schoenoprasum Alba 
• Taraxacum officinale (dandelion)
  
• Dianthus deltoides (maiden pink)
• Centaurea nigra (lesser knapweed)
• Festuca arenaria (dune fescue)
• Leucanthemum vulgare (oxeye daisy)
• Briza media (quaking grass)
• Primula vulgaris
• Gallium verum (lady's bedstraw)
• Origanum vulgare (marjoram)
• Geranium pyrenaicum (hedgerow cranesbill)
• Viola tricolor (heartsease)
• Lithospermum officinale (gromwell)
• Centaurea scabiosa (greater knapweed)
• Pilosella aurantiaca (fox &cubs)
• Oenothera biennis (evening primrose)
• Cynosurus cristatus (crested dogstail)
• Hypochaeris radicata (common catsear)
• Dianthus armeria (Deptford pink) (more of which in a future post)
• Armeria arenaria (Jersey thrift)
• Tussilago farfara (coltsfoot)
• Sedum acre (biting stonecrop)
• Lotus corniculatus (bird's foot trefoil)
• Leontodon autumnalis (autumn hawkbit)
• Agrimonia eupatoria (agrimony)
• Silene vulgaris (bladder campion)
• Erigeron acer (blue fleabane)

And so to the ladder....

 When I was at school I remember one report from my maths teacher which read 'Jane understands the theory but tends to rush which causes silly mistakes'. This one phrase pretty much sums me up. Thus it was with the long, heavy ladder I was manoeuvring into position when, in a miscalculation of Benny Hill proportions, I managed to hit myself on the forehead and knock my glasses off. So given my historic clumsiness, my tendency to suffer vertigo at heights, and the recent head injury, maybe I should have avoided the roof, but you know what?  It may have been this head injury, or just the fresh air, or the thrill of being child-free for a morning, but once I got up there, it felt delightful (that may be why I look rather deranged in the photo above). I felt pretty safe, aside from trying to get back down the ladder, which was a bit hairy.

The planting proved a lot more calming than ladder wrangling.  I tried to avoid a boring grid of plants, leaving some areas bare and grouping plants in other areas, and ridging the soil to change the depth here and there. So now it's a question of waiting to see how it evolves. I am aiming to take a weekly photo of the roof and put it on Flickr to show how it changes through the course of the year.

 

*I'd recommend British Wildflower Plants' plug plant selections for green roofs - they were the best value plants I found, and they arrived in good condition. The only downside is you don't quite know what you're getting as you choose between four 'mixes' that include any of a long list of plants, so I ended up with a couple of things I already had, or could have sourced simply for free, such as daisies and fox and cubs.