Digging a Hole to Fill It Back In

My little greenhouse needs a sturdy, level place to set her feet. Today I'm preparing that space for her!

There is a fairly steep slope right in the spot I hope to have the greenhouse (in the picture, it's the area to the left of the brick patio), so I'm building a small retaining wall to hold the soil in place. All those pots are full of dahlias, but they are a story for another day. I did plenty of research online to make sure I understood the wall-building process. Then I followed these steps:

Step 1:
Dig a hole in a straight line, with an approximately level bottom. (Forgot to take this picture) Tamp down the soil in the bottom of the hole. You can use a hand tamper, but since i didn't have one, I used a brick like a heathen.

Step 2:
Fill the hole part-way with special gravel that is designed for this purpose. The special gravel tamps together well and is a nice sturdy base. This layer needs to be pretty much level, but don't kill yourself leveling it. Tamp down the gravel (again, hand tamper or brick.)


Step 3: On top of the gravel, add special leveling sand. As before, special sand is important because when you tamp it, the grains lock into place and don't shift around. Regular sand is shifty, hence the term "shifting sands". This level must be level.


Step 4 - 65:
Apply blocks. Level blocks side-to-side and also front-to-back. You don't want a wall that is lean-y in any direction. If a block needs adjustment, pound on it with a rubber mallet. If you don't have one, put a piece of wood on top of the block and hit it with a brick. Thats what I did. Once the blocks are all in place, backfill behind the wall with soil.


I used wall blocks that have a lip on the back, so they don't need mortar. This is much more DIY-friendly than cinder blocks, which must be mortared. The lip on the back of the block slides up against the back of the block below, so as the soil behind the wall pushes forward on the blocks, they lock more tightly into place.

I purchased 60 blocks for my wall, which ended up being 3 blocks short of done. Shoot! I will buy those tomorrow and finish up. Here is how the wall looks currently:

It looks really tall in the picture, but in reality it's only about 2 feet. Tomorrow I will add the last 3 blocks and continue backfilling. I'm really pleased with the wall. It feels sturdy, is very level, and looks pretty good. There is just enough room between the wall and the fence for me to walk. Now I just need to move several hundred lbs of soil for backfill and I'm ready to install the greenhouse!!