Beginner Gardening: Terracing?, 1 by ecrane3

ecrane3 wrote:
The cheapest material for retaining walls (assuming you have to purchase materials, vs finding someone giving away stuff for free) is pressure treated wood. I've attached a picture of the wood retaining walls in my yard back when the landscape was still a work in progress. Trouble with wood is it won't last forever, but if you use pressure treated it'll last a decent number of years and it's certainly cheaper than stones or landscape block.

Regardless of what you use, make sure you read up on construction of retaining walls. It looks like you'll need one(s) that are a decent height so you'll want to make sure there's drainage behind the walls so they don't bulge out from the pressure of wet soil behind them, etc. Also I don't know about the rules in your area, but here if you're building retaining walls more than 3 ft tall you need to get permits, so it'll make your life easier if you keep yours 3 ft or less (my tallest one is 3 ft, others are a little shorter

You might also consider amending your soil with some organic material as you install the walls...decomposed granite would have great drainage but I'm not sure how many nutrients it will have for your plants so they'd probably be happier with some nice compost mixed in.