Potential green roof plants

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Novak
Title: Member
Joined: 2009-10-07

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.

Janet
Philadelphia, Pennsylvania, zone 7a
Webmaster for the Delaware Valley Chapter (dvcnargs.org)

Lori S.
Title: Moderator
Joined: 2009-10-27

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)... ?

Lori
Calgary, Alberta, Canada - Zone 3
-30 C to +30 C (rarely!); elevation ~1130m; annual precipitation ~40 cm

Tingley
Title: Member
Joined: 2013-01-07

Greenroofer:

Quote:

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.

Southwest Nova Scotia, zone 6b or thereabouts

ClifflineGardens
ClifflineGardens's picture
Title: Guest
Joined: 2013-01-14

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.

ClifflineGardens dot com

Fort Collins, CO zone 5b

Gene Mirro
Title: Member
Joined: 2010-02-25

Clarkias, poppies and many other annuals will self-sow so thickly that the plants will be too crowded to bloom.  In the garden, I can just thin them with a hoe.  Not sure how you would handle it on a roof.

SW Washington state, 600 ft. altitude

Tingley
Title: Member
Joined: 2013-01-07

Quote from Greenroofer

GreenRoofer wrote:

Quote:

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.

Actually, the extreme south of Nova Scotia is zone 7A. Not many folk realize we are as far south as roughly Eugene Oregon, or Marseilles, France, but without such mild weather. Yes, the ocean and Bay of Fundy moderate the influence of the rest of the continent, but we sometimes still get winter blasts.

Clarkia would likely perform well as a green foof plant. I wonder.... if you are looking for something in a bit different hue- would Lithodora survive where you plan to use it? Lithodora Grace Ward is a stunner when in bloom.

Southwest Nova Scotia, zone 6b or thereabouts

ClifflineGardens
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Joined: 2013-01-14

A green roof plant is described thusly;

1) drought tolerance (xeritolerance)
2) preference for gritty soils with perfect drainage
3) low nutrition needs
4) full sun
5) not tap rooted, media depths are inadequate to make this adaptation useful
6) prostrate or wind adapted
7) cold hardy one zone beyond that in which it is planted, zone lowered with greater height
8) provides soil cover, or has a stunning flower as an accent plant

Many people try to point to barrens, glades, or cliff lines as being similar to a green roof. Take one of those ecosystems, remove 100% of the fractures in the rock into which roots might generally grow, and elevate it 15 - 650 ft in the air with shear drops on all sides and you have a green roof. Media depth is generally from 3 1/2 - 8 inches. 3 1/2 supports various succulents, mostly sedum. 5 - 7 supports prairie. >7 can support larger species like shrubs. 80 - 90% fired ceramic aggregate as media, 20 - 10% long term stable organics.

What plants grow in your gardens, that just refuse to die? When you bake them in the hot sun, and forget to water them, and they send up bright and happy growth regardless? Plants which grow and provide cover where nothing else could thrive, in just a few inches of grit? What serves you selflessly no matter the droughts you face? Tell me the names of these plants, for they are very...precious to me.

ClifflineGardens dot com

Fort Collins, CO zone 5b

ClifflineGardens
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Title: Guest
Joined: 2013-01-14

Lithodora seems to have average water needs, which is beyond a green roof. I love plants of the Boragincaceae though, and would love this gem in my own future rock garden.

ClifflineGardens dot com

Fort Collins, CO zone 5b

Gene Mirro
Title: Member
Joined: 2010-02-25

The first thing that pops into my mind is plants that store food and water:  cacti, bulbs, taprooting plants.  Have you tried tulips and crocus?  How about the dryland native bulbs of the western US, like Brodiaea?  You said taprooting plants aren't a good choice, but I would give these a try:  Lupines, poppies, Mentzelias, Platycodon, Gentiana septemfida.  There is also a huge range of spring-blooming annuals from California that might work.  How about the strong-growing rock plants like Dianthus deltoides, Helianthemum and Iberis sempervirens?  The dwarf conifers are very tough plants.

SW Washington state, 600 ft. altitude

Tingley
Title: Member
Joined: 2013-01-07

We have been playing around with one of the "Hardy Ice Plants"- Delosperma cooperi, it is tough as nails. This year we'll add another species to the mix D. nubigenum. Cooperi has such brilliant metallic hot pink blooms, and nubigenum adds equally bright yellow blooms to the palette. Naturally they wont be placed together, the colour contrast would be far too loud! There are several hybrids out there that are patented (such as the 'Jewel of Desert' series), meaning that propagation is an issue without prior agreement and royalties being paid. Delospermas have been extremely resilient plants for us. They propagate on a whim. We are on the lookout for new species to broaden the colour range available in this part of the world.

Southwest Nova Scotia, zone 6b or thereabouts

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