First time flat owner, best plants for outdoor window boxes?

[Kit Kat Kaboom]

My flat is located in Prague, Czech Republic... which means Spring and Summer temperatures range from 40 to 90 F between March and August.

My window box gets moderate sunlight.

What plants would be suited for this type of location?

I was thinking either some type of herbs or small flowery type plants...I really have no idea.

Note:
This is actually my first time doing any type of gardening or "plant" work so any advice is appreciated!

Thanks!

 

[stainless steven]

have a look through the range of succulents at your local garden centre.