Ornamental grass suggestion for Toronto

[vern1]

Hi everyone, I have just put in a retaining wall behind my patio. It is semi circular about 20ft long. There are a series of limestone blocks in front of the retaining wall so anything planted in this bed will need to grow to 4-6ft in order to be seen from the house ie the plants will be behind the limestone blocks.

I would welcome any suggestions on ornamental grasses that would be good for Toronto and grow to 4-6ft or higher. Other perennial suggestions would be most welcome. This area gets sun from about 10am till around 6pm this time of the year. Because of the construction there is not a lot of soil depth, maybe 6 inches, so it cant be something with deep roots. I would also like to prevent soil erosion so will put ground cover or something between whatever plants/grasses go in here

Thanks!

 

[Tetters]

Hello Vern, and welcome. Miscanthus japonicus is a lovely big grass, but I like Stipa gigantea best of all. I planted a Stipa last summer, and at the moment it is showing flower, and it is amazing when the sun shines on it - it is like a ''see through'' screen.
I would be worried about the depth of soil however, and don`t like that ground cover stuff - it doesn`t help the soil at all. I wonder if you could work out how to give your grasses a big more root space to keep them happy. They won`t reach a good height upstairs if downstairs is starved. Good luck

 

[Verdun]

Much the same thinking as Tetters......6" of soil is not enough for a 4 to 6' grass. Miscanthus too need reasonable moisture to do well.
The only grasses that will do well there are festucas, stipa tennuissima and hordeum jubatum
Ditto for tall perennials Vern....but some agastaches will reach 4 or 5' and thrive in hot conditions.; some taller salvias as well
Artemisia Powys Castle grows to about 3' and would cope with limited soil depth. The curry plant, helichrysum italicum, too. And convolvulous cneorum for another silver plant. Achilleas, santolinas, diosmas, argyranthemums, osteospermums, eryngiums, etc.
If you could increase the depth of soil to, say 12" or more, your planting options for taller plants would increase

 

[tbendl]

The other possible option would be to put planters up on top and grow a hanging plant like an ivy that would eventually hang down and cover that wall. Then you could use the bottom area for uplighting possibly.

 

[vern1]

Thank you for your suggestions. I will check out all these options. I have some options to increase the depth as its not near the top of the retaining wall. I can probably get close to another 6 inches of soil in there and that sounds like it would help a lot.

I could grow shorter plants but it would be ideal if they could be seen above the limestone blocks (ie the big ones on the above left of the pic). Otherwise people would only see the plants if they walked to the back of the pool and looked over in to the ravine

I will forgoe any ground cover if it wont help

Thanks!

 

[Verdun]

Excellent if you can increase the soil depth Vern
For mid height grasses, deschampsias are excellent. Calamagrostis, a bit higher, is lovely in summer. Karl Foerster and Overdam (variegated with slightly later flowering) are esp beautiful with the sun shining through them. Stipa Arundinacea and carex testacea will give evergreen orange to olive colours

 

[Tetters]

Vern, is that a dry wall? I`m a bit worried about stability. When I built my own walls I back filled with soil after each layer of stone, and placed the next layer a fraction in more, so that the wall ended up leaning inwards slightly - thus making it stronger There will be huge pressure behind that wall once it is completely filled, and the higher you go the weaker it could become.

 

[tbendl]

I agree with Tetters, especially if you get a heavy rain and it adds water to the weight of the soil.

 

[vern1]

Vern, is that a dry wall? I`m a bit worried about stability. When I built my own walls I back filled with soil after each layer of stone, and placed the next layer a fraction in more, so that the wall ended up leaning inwards slightly - thus making it stronger There will be huge pressure behind that wall once it is completely filled, and the higher you go the weaker it could become.

Not sure by what you mean by a "dry" wall but each layer of the wall is backfilled with 3/4" gravel about 18" in from the block and packed down before the next layer of gravel went in. The block are staggered ie the back of each block overlaps with a groove on the back of the next layer so the wall does gradually lean in. There is a ton (literally) of compacted gravel behind the wall separated from any soil by filter paper. Soil was added for the last few layers so the plants could grow. The gravel will act to drain any water that gets in to the bed. Did lots of research before I tackled this. Appreciate the concern though

Would also be interested in any other perennial suggestions that are good for zone 6 or 5. Looking for options that would have something blooming in each season

Someone suggested mugu pines (sp?), with some lavender, gerbers, daisies and the grasses.

Thanks