I have the same problem. My front porch concrete slab is about 2 inches higher than the front concrete walk. There is a strip of about 2 feet of soil between the porch and the walk. For many years it had some junipers growing there, so the low soil level was not a problem. Finally took out the old junipers (they had gotten old and ugly), and the resulting soil bed washes out onto the walk. I have been looking for something that would edge the walk, build up the height, and yet not take up too much of the 2 feet of planting area. It has to be attractive, as this is my front door. I was in the local big box home improvemnt store (you know the one I mean)last week. They were getting in shipments of stone items for the spring. One really caught my eye. It is a man made flat stone with all edges smooth except for one edge that is rough. The shape is rectangular, and the stone is only about 1.5 inches thick. This stone is designed for stacking to make a retaining wall. I am going to make a narrow trench along the concret walk, level sand into the trench. Then I will place these stones with the rough edge up at a height that will make it level with the opposite concrete porch slab. I plan to then use metel edging along the inside of the stones to help keep them in place. The edging will be low enough to be barely seen, or at the soil level. I think the edging is going to be important to keep things from moving around in the future. This will give me a smooth edge of stone exposed from the walk. This is good for sweeping and snow removal. The top has a rough look that I like. The stones are thin enough that I am not giving up much planting area. Go to the home improvement store and look at the options. Look at all items, as you may find something that is designed for another use that will work for you. They also have precast edgers that are okay. I will not do my project until next month, but will let you know how it comes out. D

The new soil won't hold the edging in place. You'd need to show a picture of the situation if you want brainstorming.

Yes -- I use them. They're not precisely cheap but if you collect a few over time, you'll have what you need. They do need to be stacked 2 blocks high, I discovered. You can see the start of one bed on my blog, sort of near the bottom. My blog is Alla's Little Acorn at Blogspot, if links don't work right. There's a photo of the first bed in a new spot, and an explanation of why I tried this, and yes indeedy, it does work nicely. http://allalittleacorn.blogspot.com/ Here is a link that might be useful: Alla's Little Acorn

This is our 3rd season for concrete block square foot beds. We use the heavier (for stability)concrete ones which cost $1.00 apiece last year from a local supplier (Home depot and Lowe's were a little more expensive). First year we made 4x8 beds, 2 blocks high. To get 4x8' interior space it took 40 blocks (seven each end and 13 each side, overlapped). Also used 18 flat blocks to cover the holes at $.70 each, so a 4 by 8 bed was $52.60 total, which was definitely cheaper than plastic wood. You may only need 1 level high, depending on your existing soil. Top flat blocks are nice to sit on and easily removed to plant in holes, stick in a trellis, or set on the ground when muddy. Grew marigolds and herbs successfully in holes. You can carry a few in your car, so just depends on how many you need and how many trips you want to make. Last year we expanded the beds to 4x16 interior so had them delivered. We just hand leveled (well, fairly level!) as we set the blocks ourselves, slow and heavy, but you only have to do it once! Also rolled landscape fabric around the inside edge of bed before filling with dirt, helps keep moisture in. First year filled with bags of compost & topsoil, but last year ordered 'topmix' of mushroom compost, topsoil & sand delivered & shoveled in, mixing in a few big bags of vermiculite from Atwoods. After initial labor it's wonderful to add a little more soil, measure & plant as I'm doing now that our icy winter has finally thawed. I can email photos if interested.