sloped backyard but with retaining wall
We just bought a house on the AL/GA border. We love our house but the backyard needs some help and we are both novice gardeners/land caretakers. When coming out of the back of the house there is about 10 feet and then a three to four foot retaining wall. Behind the wall is a three foot wide trench that we are hoping to get the builder to back with a silk fabric, lay in a perforated drainage pipe and then fill to almost the top of the retaining wall with gravel. After the trench starts the slope.
The slope is about 16 feet deep and 110 feet wide. Erosion is a slight issue during strong rain which we do get here occasionally and it is in full sun all day. We really need to keep the cost down and it has to be pretty low maintenance so we were trying to formulate some ideas and hoped that some of you might be able to help us.
Our thought was to weed eat it, put some weed blocker down, and then do some landscaping. The idea that we had was to plant three shrubs in each upper corner and then create four to five 8 foot long by 6 foot deep planters in the middle. Those we would probably terrace a bit so that they are more level than the rest of the slope. (They would be created out of landscape timbers and rebar stakes and then filled partially with gravel and topped with top soil) In the planters is where we would do herbs, flowers, etc. The planter will probably be staggered a bit for some more visual interest and all area around the planters to fill the rest of the space would be mulch. Maybe at a later time we could add more shrubs or plants but like I said, there is only so much we can afford to do. Oh, and to deal with the erosion issue, as the property above and behind us drains down on our yard, we were told that a "check" should be installed using medium sized boulders in an 18-24 inch deep row along the upper back fence (we worry that this too might be expensive and quite back breaking to put in).
Sorry this is so long but we are so frustrated and any advice and/or tips would be helpful. Please tell me what you all think of this and if it's something that would look nice and be done relatively inexpensively. Also, any plant suggestions and alternatives to the boulder check would be appreciated. Thank you all.