Question
Hi
This may not be your area, but my main question is about the easiest, cheapest way to build a retaining wall that has a slight curve in it. Stone is hard to find. I'm a do it yourselfer, but limited on time. If you don't know about this kind of stuff, maybe you can refer me?

Also: best grass solution for dry shade?

Thanks so much for your time
Rondi


Answer
Hi Rondi,

All turf grasses will need an average of at least 1-3 inches of water per week to do well.
Even the best shade-tolerant grasses will need so-much dappled sun-light per day to do well.
The most shade-tolerant turf-grass  available these days is a TALL FESCUE. Cultivars named 'Rembrandt' and 'Plantation' are the highest rated.  The seed is widely available for zones 4-8.  With persistent 'deep-shade', you may want consider other types of grond-covers like IVY.


Building retaining walls is an engineering project.
The really good retaining walls are quite costly to build, just ask the State and Federal Highway Department of the USA,...they build the best in the world. How about $5000 per linear foot?

There are these days excellent pre-casted inter-locking stone blocks to use for residential retaining walls,... but these are anything but cheap. They are heavy but about as easy as it gets to install however.  Some people are renting cement-mixers, buying concrete and making their own such blocks. You have to see examples of these at landscape suppliers, or places like Home-Depot, or stone and brick suppliers. Find some examples (also search on the web), and consider the possibility of making your own 'form-molds' to pour your own version of these.  Plastic carboys might make a potential starter for a mold-form. These are 'cuboidal' sometimes in at least the five-gallon-size.  This is rather labor intensive but can have satisfying results and can last indefinitely in the landscape. Your retaining wall may out last the Pyramids.
You may not need the cement mixer if you can take your time at it otherwise.


Much depends upon how high the wall needs to be.  It is also important to consider the weight and mobility of what  (the 'up-hill' soil mass) will be retained in regards to the type of soil.  Certain types of soil are not easily held back when big rains come, so you need a very secure and solid retaining wall especially for any height to hold.

I consider a 'short' wall to be less than 18" or so.
As much as one-foot more may need to be securely set into the ground. A sandy soil may be difficult to retain without having footings going much deeper.  You will have to experiment and decide.  This type of retaining structure can be made with rail-road-ties or landscaping timbers and some sort of soild backing sunk into the ground on the soil-side.  You can use weed-barrier material as a liner behind timbers for this purpose and the lumber-yard may have other sheathing materials that can work in curves.  I have also used roofing materials and tar-paper.  The lining needs to be water-proof.  It can and should 'seep' but not potentiate a wall-break.  You can use galvanized metal sheathing, wide-flashing metal, or weather-proofed lap-board siding for timber-backing.  I have seen timbers placed either horizontally or vertically. A rail-road-tie set into the ground can give great retaining strength,...but you may only get less than a foot of length; they can vary in width but be more than six-feet long.  If sunk three-feet into the ground, you will have a strong 3' high retaining wall (plus the backing materials).   These backing materials may come in various length that you can make into curved-sections.  The lap-board pieces can be ordered quite long and require a flat-bed truck to transport in the big city,... or you can have the lumber yard deliver them to your property for an extra charge. The lap-board pieces that you may find may be the standard width, or they may offer some wider versions.  You can try to build height by joining these securely.

The biggest problem your budget-crunched project may confront is what can happen with a big rain and tons of water (or mud) coming down-hill.
These things can not always be well predicted, but with improved planning and engineering skills,...you can build something that will last.

At your public library, you may find excellent books on how to build retaining walls.  People who write such books tend to combine this topic with similar topics ( patios, decks,...etc).

Good Luck,
Jim G.