Degradation of the border material is another consideration you have to remember. Yes, wood will eventually decay and rot, providing new pathways for the grass to penetrate the garden. Bricks eventually crack, and frost can heave and separate even the most permanent of materials like stones set in mortar! Again, given time, grass will eventually find all of these nooks and crannies. It can be a pain like that!
So, a good, solid and well-maintained garden edge will not only help with the health of your lawn but also provide a safe growing environment for your beloved plants.
Steel edging is the most common metal edging, although you might not find it at local nurseries. Look for it at larger garden centers or at landscape suppliers, which is where most pros get it. Keep in mind that it'll eventually rust, especially in a salt environment, like on the Sunshine Coast. It's heavy, floppy stuff and needs almost full support when you transport it.
Aluminum edging, besides being lighter and stiffer, won't rust and is also available in a wide variety of colors. Look for it through landscaping suppliers, although it might be difficult to find.
You'll find black plastic edging at every garden center and home center, sometimes in both regular and heavy-duty thicknesses. Buy the thicker material.
1: Dig the trench
Cut a narrow, 8cm- deep trench with one vertical side along the lawn edge. Shave the vertical edge to smooth out curves.
2: Place the edging in the trench
Connect the border sections, drop the edging into the trench and lay it against the vertical edge.
3: Support the edging with stakes
Drive stakes to set the depth at about 2cm. above the soil level of the lawn. If the edging drops too low, pry it up with the tip of your shovel.
4: Backfill along the edging
Backfill with soil from the garden bed and compress it firmly. Leave room on top for mulch.