With some good research, a lot of patience, and some hard work you can build a wall like this on your own. I like to use natural stone for walls like this; it gives the finished product a much nicer look than using traditional retaining wall blocks.
The first step is to mark out the border of your garden where you will be building the wall. Remove the grass and begin to level the ground. The wall needs to be wider at the bottom than it is at the top, so dig a ditch a few inches deep and about 18" wide. For taller walls you may need a wider base.
Once the ditch is nice and level, fill with a few inches of gravel base. The base material is commonly reffered to as modified 3/4 base. This blend has rocks up to 3/4" all the way down to dust; this allows the blend to compact very nicely. You can use a hand tamper to compact your base, or if you have access to a plate compactor that will make it much easier.
Now that your base is ready, you can begin laying your first course. Select big flat stones for your base and use the thinner stones as you build higher. This is the part that takes a lot of patience. Using natural stone is a lot like putting together a puzzle. Take your time making sure each stone fits in place nicely and doesn't rock back and forth on the stones beneath. You can set up a string line to make sure your wall is going up level.
Backfill your wall every few courses as you go with 3/4" stone to allow for adequate drainage, and to ensure there isn't a lot of pressure building behind your wall. If done correctly, a dry stacked wall like this one can be surprisingly durable and long lasting. Just remember to take your time and be patient!
If this seems like a bit too much for you to tackle on your own, and you live in the South Jersey region, give us a call at 856 745 5264 and we'll take care of it for you!