That what a garden hoe is for. You are gonna have to pull weeds and grass at least once every 2 weeks. No matter wat u do..

Take a look at "Eraser - Systemic Weed & Grass Killer." I got it for edging but haven't used it yet -- to take care of some bermuda (from an unknown source) and zoysia growing in spots around my edges.

Do you have any type of barrier between the garden? I have a client that we put a small concrete strip that gave it a better appeal and reduced the grass creep into the beds. Just an idea. There are different types of barriers you can use

Here is a link that might be useful: My Website

We use metal landscape edging. Concrete looks pretty good. For some grasses it has to go pretty deep (at least 6 inches).

A concrete paver border works okay, but is quite a bit of work to install. I put mine in to save myself some effort with the string trimmer, and be able to mow up to (and over) the edge of the lawn:

The look doesn't appeal to everyone, but it's sturdy, durable and generally attractive, to my eye anyway.

More pictures and an install guide here:

http://havingfunalongtheway.com/building-a-mow-strip-for-your-lawn-part-1/

I think that looks awesome pwlong. Nice diy work...looks really straight and level.