Potential green roof plants

[Janet Novak]

I'm trialing Aquilegia caerula, and A. canadensis. I'm hoping they like growing in 6inches of gravelly medium in the hot dry sun.

I'm betting that Aquilegia canadensis will do just fine. In my garden, it thrives in full sun in a limestone barrens: 8" of limestone gravel over hardpan. Admittedly, my plants have the advantage of access to the subsoil, but still... even during droughts they never wilt.

[Gordon]

Speaking of Green Roofs, this article appeared in the Vancouver Sun Blog reviewing the huge green roof installed on the expanded convention centre, prior to the 2010 Winter Olympics.

Here is the link to the blog post: http://blogs.vancouversun.com/2011/11/24/grading-vancouvers-giant-green-roof/

Plant materials are listed, and some of the photography really brings home the size of this new downtown meadow they created.

[cohan]

Interesting project! I agree more public viewing areas would be nice, and sprucing up the public area mentioned, but I think there are a couple of somewhat conflicting views here-i.e. the writer vs the landscape architects. On one side, the planners/planters seem to be most interested in representing, preserving, expanding habitat for native species of plants, birds and insects. The writer acknowledges that this aim seems to be quite well achieved, but in looking at the planting as a 'garden' rather than a habitat restoration seems to find it falls short on criteria of aesthetics and public access (public access at some point of course comes into conflict with the needs of habitat maintenance)..
So, two somewhat different ideas about what might constitute success. I think it's probably important for any public project to find a balance between them, in order to meet environmental protection objectives and still keep the public interested and on board!

[GreenRoofer]

I'd like to share an image of one of current favorite green roofs. I really like this design. from GreenRoofTechnology.com. Simple, effective.

[cohan]

Looks like the occupants of those 3 chairs would have a great view in front of them, close and longer range...

[Hoy]

I'd like to share an image of one of current favorite green roofs. I really like this design. from GreenRoofTechnology.com. Simple, effective.

A nice one! Almost like a meadow

[GreenRoofer]

Glad you like the images, it's a cool company. Here's an image of my trial roof, found it the other day and thought it would be nice to share. It's a prairie restoration on a rooftop. 90% native. The grasses are filling in well.

Native Illinois prairie plants on this roof that would work well in a rock garden in my opinion:
Heuchera richardsonii (Saxifragaceae)
Opuntia humilis (scars on my hands from weeding around them, but still lovely)
Talinum calycinum
Antennaria neglecta/dioica (literature cites allelopathy, haven't seen evidence of it myself though)
Silene regia (Tall at 4' but very narrow, doesn't get as tall on the roof, maybe 1.5')
Callirhoe involucrata (stunning pink flower, nice foliage, procumbent habit)
Anemone cylindrica (seedheads really look like thimbles)
Dalea purpurea (Stunning purple flower, interesting foliage, and seed head that's fun to pull apart, N fixer)

Of any of these though, I think everyone should grow Talinum calycinum, they could not be happier, more well behaved, generous little plants. Often called an annual, I have found mine to be consistently perennial in zone 5. Their bright pink flower opens for a short while in the early evening in the direction of the sun. Loved by bees, the flowers dance on their thin stems in the slightest breeze. Everyone should throw a packet of this into their rock garden. They spread, but never to the point of nuisance. They spread like Aquilegia or Corydalis. Easy to prop from cuttings, but even easier from seed. I intend to make this species extremely available to the next seed exchange.   

[cohan]

Nice set of plants there- Talinums are favourites of mine, but only theoretically so far- I don't have any yet, but love any hardy succulents 
So how long post planting is this roof?

[GreenRoofer]

Awesome green roof - 5 inches of media. That inch beyond an extensive roof of 4 inches really opens up your plant palette. Irrigated.

http://www.roofmeadow.com/wp-content/uploads/Pacific_Plaza_2011_05-7.pdf


What is that pink flower? It's gorgeous.

[GreenRoofer]

Nice set of plants there- Talinums are favourites of mine, but only theoretically so far- I don't have any yet, but love any hardy succulents 
So how long post planting is this roof?

It's hard to say, I started work on that system in May of 2011, planted some that first summer, planted more this summer from nursery stock and my own grown trays, then added more seed this winter.

[RickR]

Looks like it is coming along quite nicely!

Dalea purpurea (Stunning purple flower, interesting foliage, and seed head that's fun to pull apart, ...

Gee, I find nearly any seedhead fun to pull apart. 
Dalea purpurea in the wild (Minnesota).
     

Of any of these though, I think everyone should grow Talinum calycinum, they could not be happier, more well behaved, generous little plants....

I don't think you'll find any disagreement there.  Phemeranthus(Talinum) calycinus, or just about any Phemeratnus or Talinum, would/are welcome volunteers in my pots, too.
     

[Janet Novak]

Interesting that allelopathy has been reported for Antennaria neglecta. I also haven't seen any evidence of allelopathy, and I've grown it for years. I do get a nice crop of American painted lady caterpillars on it every year.

[Lori S.]

I really like the Vancouver example!  Looks fantastic!
Not sure if it's correct or not (maybe just a false impression) - the plants on the Tacoma roof look like they were planted in rows(?).... Always a bit disturbing to my eye (preferring the randomness of nature, though, as I say, I may be totally mistaken)... ?

[Gordon]

Greenroofer:

What is that pink flower? It's gorgeous

I think the plant you called out on the Pacific Plaza roof in Tacoma is likely some species or hybrid Clarkia.

[GreenRoofer]

Nova Scotia contains zone 6b? Thats wild, must be the ocean currents? I went to school in Carbondale, Illinois and that was zone 6. Which is 6 hours south of Chicago by car.

Clarkia...looked it up and it might be a great green roof plant, my selections of plants for sloped extensive roofs are all tending towards the color pink! I hope it doesn't offend the heteronormativity of the roofing industry. I'm wondering if the color pink is beneficial to xeric survival in succulents outside the Cactaceae. Does the color pink go a distance or attract a specific pollinator...flower color and morphology are fascinating. It's so cool that some flowers select their pollinators as much as the pollinators select the flowers.

I'm a bit leery of annuals, perhaps I should withdraw from that bias, so long as they are self-seeding.