This is how I built this raised herb garden out of recycled masonry parts. I will give you the steps I took, and a few other options to include in yours if you wish.
Step 1: Gather Supplies
- 4' screed board (straight 2 x 4)
- Level (optional)
Whatever blocks you are using, here is what I used:
- 5 chimney tiles (12")
- 4 (2-hole) cinder blocks (8" x 8" x 16"). (Cement blocks are ok too they just weight more and may cost more if you are buying new.)
As I was recycling masonry parts I should point out I was lucky enough to get chimney tiles that had been installed as a false chimney so there was no creosote. Creosote from coal is toxic, creosote from wood is used medically (see creosote.) If you don't know what was burned in the chimney before you may not want to use recycled chimney tiles.
The cinder blocks are a newer style so they are square on the ends, older ones have little tabs built out on the ends that will leave a 1-2" space near the tiles that is too small to plant much in.
Step 2: Prep & Level Your Site.
Choose your build site and remove any plants already growing there, if any, and any rocks that would keep you from getting a level site. The pattern I made with the blocks took up an area of about 3' 6" (107 cm) square. The blocks you use are going to determine what the size of your build site will need to be as well as how many blocks you end up using.
- For your first option you will need to decide if you want the blocks used to stand at their full height off the ground, or if you want them sunk more into the ground to lower their height. The blocks are more to control the spread of some of the more aggressively growing herb and keeping spreading weeds out of the herbs.
- Using there height as a decorative touch or to make collecting easier is a bonus to the user.
- If you are sinking the block into the ground you will need to dig down the depth you want the blocks lowered.
- IE. You only want the garden 8" height and your tile is 12", dig out 4" to lower it.
Once you have the ground cleared, and dug down if setting the blocks lower than grade, you need to make sure the ground is level and flat.
Note - level and flat are not the same. Flat is having a smooth even surface. Walls are flat, roofs are flat, but neither is level. Level is having a flat surface that has no slope to it.
Use the screed to flatten the area so that there are no lumps or low areas that need to be filled. The screed needs to be as long or longer than the area of your build site. Pull or push the screed across the area back and forth and from side to side to make sure it is flat both directions. At the end of flattening the area the soil should be flat and packed down to stop settling which will make the blocks sink and tip.
*Optional - You can use the level to make sure the are is completely level if you wish. I just eyed it.
Step 3: Setting Your Blocks
Before you set your first block you are going to need to decide if you need to add some varmint security to your raised garden. If you have little furry burrowing pests that like to raid your garden then you may want to put down a layer of hardware cloth to keep them from going under your blocks and burrowing up into them. If they are not a problem in your area then you can skip this and move on to just setting the blocks.
Start in one corner of your prepared area and set the first corner. For me it was a chimney tile. I then placed two of the cinder blocks, one on each side of a corner extending to the next corners. The cinder blocks were thinner than the chimney tiles so I set them to center with the tile center. This made it so the chimney tiles stuck out a bit further than the cinder blocks but it looked good so I kept the look.
Set a chimney tile at the ends of each cinder block, centered with the cinder blocks. These designate the next corners of the garden.
You need to eye the layout and see that everything is looking straight as you will be setting the last blocks next. If you are a perfectionist and your OCD requires use a straight edge to make sure they are perfectly straight. I don't mind a little creativeness in my garden and just went with the eyeball method.
Set the last two cinder blocks, one off each chimney tile enclosing the center of the garden, again center them with the tiles.
Set your last outside chimney tile at the open corner. Since this is a dry stacked block garden you can check that they look straight and move them as needed, or for the OCD crew make sure they are straight and square with your level, a square and your best geometric proof. I'm good with the flats of the blocks touching and they eyeball as straight.
I put my last chimney tile in the open area in the middle of the blocks to give a center planting area set off from just having the large open area in the middle.
*Option - Center Tile Lift. If you want the center tile a little taller than the corner tiles you can put some pavers or stepping stones under it to lift it to the height you want for your design. Mine sits at the same height as the corner tiles.
*Option - More Planting Areas. If you want the area that surrounds the center tile to be further broken up into individual planting areas you can put pavers or stepping stones between the corners of the center tile and the corners of the corner tiles to have four thin planting areas around the center tile, instead of the one thin planting area that goes around the entire center tile.
Step 4: Add Soil & Plant
Fill the tiles, blocks, and areas between with soil. I filled all of the spaces to the top with soil and had to add a little more after I watered it the first time since it settled after watering. You will have to judge for yourself if the soil you are using will settle a little or a lot after watering, and how much to add without packing it down so hard the plants won't grow.
Once the soil was added I planted the area according to how much room each herb needs to grow and how much they spread. Herbs like peppermint and spearmint are aggressive growers and can spread like mad taking over large areas if not controlled. Others might not spread as much but you may use a lot more in your cooking. So plant according to your use and the how aggressive the herbs grow.
I put the taller rosemary in the center, parsley in one behind that to use the shade of the rosemary as it is not as tolerant of the hot sun here. Filled in the area surrounding the center tile with chives since I had a lot. Sage, basil, and dill in corner tiles, and will fill in the others with different types of thyme, oregano, and others. I planted some smaller cinder block holes with marigold seeds as many insect pest don't like them, and calendula flowers as an edible flower.
One of the great things about this design is that it can be expanded with additional blocks and tiles. You can do a simple expand, extending it from one side or get fancy with your design given your supplies and building area.
So there you have it. A raised bed herb garden from recycled masonry parts that won't rot and looks great.
Hope you enjoyed it and good luck on your own build.