I'm not particularly green fingered but I do like to cook. Therefore, I would love to create some herb heavy window boxes. I mostly use coriander, parsley, mint and tarragon etc. Can I mix them in with some flowers for a bit of colour too? If so, which flowers would be best that will last most of summer and I can't kill easily? They will be on my front windows which I guess you could consider as not in full sun all day. Thanks!