This is what I want to “copy”!
How much potting soil?
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I am going to put cinder blocks at the front of house to continue the MCM look. If I stack them 3 high, which would be about 20” or so, and it will be apps 20 feet long, do I need to fill the whole thing with potting soil?
Many people use packing peanuts, water and soda bottles to fill the void and use less soil. If you have any random ugly rocks you can toss those in there too. So start saving your water and soda bottles! If planting edibles, yes I would fill with good soil. I have a thing about plastic and food. Weird, I know . . .
no...use plastic bottles, then lay landscape fabric on top, then fill with soil
Could use Gravel..........
You could use rocks, they would do well, just make sure you add soil for when it washes down into the rocks so that it will not get too low on soil. Pack the rocks or gravel in well and cover that with landscape fabric so that it drains well, but will hold most of the soil on top. I would go with ten to twelve inches of soil.
Fill so it's about 12" from top with gravel or rock mulch (cheapest available), add landscape fabric to prevent soil from washing out. Figure out cubic feet from the top of the fabric to about 3" below top of blocks and buy that amount (length x width x depth). Plant and mulch the next 2" with cedar chips or other material that will discourage cats using as a litter box! This is a beautiful installation! Good luck!
yes