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Soil, Compost & Mulch

Height of soil above retaining/garden rock wall

7 years ago

Greetings folks!

Question: We've built a two-tier (terraced) rock wall in our front yard and are now in the process figuring out soil amendments, planting/sod and such. A "gotcha" for us is our clay soil - it's bad in spots - to the point where we could probably form it into a bowl and fire it in a kiln. Anyway, we are planning on mixing in some compost and then depending on the location putting down either sod or mulch for plants/shrubs. The current height of the soil is only about an inch or so below the top of the rock walls. If we add say 3 inches of compost, mix it in, and then add say 3 inches of mulch or sod, I'd guess we'd probably be about 6 inches above the wall considering expansion from the tilling process. We could taper in that difference toward the wall to be less noticeable near the wall if needed.

Bottomline - Are there are major issues with having the beds/sod 6" above the wall in spots? I am asking because it's a major pain to manually scrape off the good topsoil (5"), push the topsoil back, and then till down to the heavy clay areas and remove sections of clay soil by hand down in some cases across two tiers of rock walls to the street for disposal. And our front yard is probably 75ft x 100ft, so the workload needs to scale to something we could accomplish in a reasonable period of time.

All comments welcome and appreciated. What would you do?

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Comments (5)

lisanti07028
7 years ago
I cannot advise you on your clay soil; I hope that someone chimes in with some advice. However, all I can see is that one good rain is going to wash all 6" of soil off of your raised bed. You will not be able to mulch any shrubs or plants, and the front roots of any sod is going to bake or freeze. Perhaps I am not understanding it right, but it would be like an overfull cup measure - the stuff on top is going to fly off.
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daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
7 years ago
You don't say what the dimensions contained by your retaining wall are. If it's just a few feet between the walls (as in, a terrace), you're going to end up with a nice layer of sod at the base of your retaining walls, as noted above. If the retaining walls surround your 75x100 yard, mounding the sod six inches over the walls in the middle won't be problematical, and as you say, you could taper the hump.

At some point, you're going to want to attack that clay. If I were you, I'd dig it out in a limited piece of bed, put in some deep good soil there, plant some perennials on top, and then plant annuals elsewhere. Do some more every year.

A thin later of sod on top of clay virtually guarantees an underground puddle.
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annuals.. perennials.. shrubs .... forums .... any chance you can post a pic or two .. so we could better see whats going on ... the bulbs should probably be pulled up as the greenery wains.. and stored like onions for fall replanting ... otherwise.. i dont know how you would ever find them ... the perennials can be dug and stored for a couple weeks.. in plastic grocery bags.. in full shade ... you could write names on the bags ...are you trying to save cultivar names.. or just general plant names .... there is a name that plant forum.. for after the project.. if you need to get names back ... same with the shrubs ... yours arent that foo foo ... if you had a veg patch.. you could move stuff over there now ... and move it back in fall ... and get the job done in between ... finally ... if you can make the moving.. an all summer project.. and the cement work done in fall ... perhaps it will be more manageable for you .. rather than making it a 'i have to do this all this weekend' type of project ... again.. perhaps a pic or two.. might bring other ideas ... ken
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kimmq
7 years ago
Rain would erode the soil above the retaining wall.
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rgreen48
7 years ago
Perhaps a few good photos would help us understand your situation. I have a retaining wall that cuts and holds the lower portion of a slope - making the soil upslope higher than the wall, but the wall itself also slopes toward a lower portion of the area... basically it slopes in 2 directions. If the soil was loose, and unplanted, there might be erosion, but there are ways to keep that from happening until you can get roots established.
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User
6 years ago
Photos, please.
0

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