apartment therapy changing the world, one room at a time

i have similar window sills. i've gone with 2 methods. you can either buy big L-shaped metal angles that screw in to the 3" exterior vertical portion of the sill you've drawn, and set the box on them. there are weight limits so don't go crazy. i've had a pretty hearty jade plant outside my window on 2 of these angles for over a year now and they haven't budged. you have to crane yourself outside the window to screw back in toward the house, so don't fall out!
secondly, you can also screw smaller metal angles into the side of the window box, set it on the 5" horizontal portion you've drawn, and screw the metal angles direclty into this 5" portion. since the 5" area is sloped away from the house, you might want to bend the angles slightly if you want the box perfectly vertical but last i checked plants can grow on hills. in this case the box is actually sitting on the sill and depending on how tall it is will stick up in front of the window. the former version, the box is hung sort of below the window. my landlord made me take mine down that were over a street (liability) but in your case, in an alley should be ok. alley cats lookout!

Hello,

I am taking a virtual trip from the AT NY blog and visiting over her in San Francisco AT. It's so sunny over here!

One option you might consider, if you don't want to screw supports into the windowsill or buy something that hooks and cantilevers, is to get a stand for in front of the window.

We bought Smith & Hawken plant stands and couldn't be happier. Here is a link:

http://tinyurl.com/22b5ex

You may also enjoy this swivel bracket, which could mount to the inside or outside and be able to swing a potted arrangement indoors for easy watering, or farther out for more sun:

http://tinyurl.com/2ygqnu

Here are two 'universal' hooking brackets that require no screws, but would not be surprised if you have already seen them on your quest:

http://tinyurl.com/23rd9c
http://tinyurl.com/2xnr59

If the sill contour is the big problem, you may try taking that drawing to a small metal shop and see what they could fashion for you. The drawing shows a lip that could be used to hook around onto if you found the right solution. It could then be further secured by some small screws to prevent a slip.

Um this looks like my apartment building. . . are you my nieghbor

Cinnamontoast3, I was just thinking the same thing.... does that window look down to the trash/recycling bins in the breezeway? Because I think I live in the building next door!

Too weird (that you guys figured out you are neighbors via an AT post).

Thanks for the visit Matt!