As the appearance of the garden has a modernist style with the straight lines and concrete furniture how about a Mondrian influence and add a bold strip of blue? It is a pond and with the right shade it could look really relaxed and contemporary. My daughter's suggestion is a chalky lilac!

Any luck choosing a color yet? Any pics you can share to get an idea of what you are working with?

If you use masonry paint, we could head in a warm greige direction for all of it - not so yellow . .. something that can give you a bit more contrast against the white windows and trim - even 40 does a lot for us . . . what about a blue green gray? You will get a coastal / mod vibe and it will relate to the farmhouse look .. .above bm silver mink http://www.benjaminmoore.com/en-us/paint-color/silvermink and below . . . gilbraltar cliffs . . http://www.benjaminmoore.com/en-us/paint-color/gibraltarcliffs Shingle look siding on the side dormers would be neat to get that cottage mod. . . you can stick with yellow but I don't think it complements the roof tone. With the blue-green grays, the white windows and trim will really pop beautifully. . . You can also go more neutral with a warm gray - greige . . . here's the siding tone http://www.benjaminmoore.com/en-us/paint-color/capemaycobblestone paired with this for brick - http://www.benjaminmoore.com/en-us/paint-color/graystone potential future red windows . . .aluminum pits over time, so if you have just one side you want to try, you don't have to powder coat, you can take a small brush and just do them by hand with latex paint if they are 10 yrs old or more. . . one advantage to gray . . future see [houzz=]

Teal? Just a thought sometimes I think it's smart to match or atleast go with the curtains you'd see in the window