Originally Posted by
Timed Out
If you want to use the pebbles in a defined area using an edge restraint is a good idea. It will prevent them from spilling over onto walkways, grassed areas etc. If you are wanting to create a modern look with the pebbles and feature pot I would go for something different to treated pine. IMHO treated pine is better suited to rustic or traditional style gardens. Boral make a range of easy to lay concrete retaining wall products in a variety of colours that look good in a modern setting.
Forget about the black plastic - it starves the ground of water and oxygen and over time makes the soil turn horrible. If you want to put down something to supress the weeds use weedmat instead - it allows water and air to penetrate it and keeps the weeds down. You can cut holes in it for the planting holes you have.
Before you lay the weedmat and pebbles I would advise digging in a good amount of organic matter (garden compost, well composted manure etc.) to improve the soil. The soil will retain moisture and nutrients better and your plants will thank you for it.