Whereabouts to make a border for annuals in this garden

[Panda]

I'm looking to make a border here somewhere for some low growing annuals like petunias, to the left side of this pic is south facing, my roses are along the wire fence to the right, beneath the tree in that border I'm going to plant busy lizzies, so I'm not sure if I should make the new border along the front of the roses and take that bit out a few feet then plant something in front of them, or make a border along the edge next to the drive or do both but the worry then is how much weeding it would take to maintain it unless it was mulched, any other suggestions or opinions please

 

[treeguy]

Make sure you have a grass barrier 3 or 4" deep and 1 or 2" above ground that whole perimeter. Metal stays in-place better than plastic, which floats up in winter. Otherwise, maintaining the beds' edges will become a burden worse than just weeds popping up. A heavy mulch of wood chips enriches as it breaks down and is easily refreshed each new growing season, or in autumn after the annuals die off.