Gardening in heavy, sticky clay soil is a complete drag. I shouldn’t totally bag on clay soil, it’s rich with potassium, calcium and magnesium – essential nutrients for plant growth. Plants grown in clay soil tend to have shallow root systems, because of the lack of oxygen, making them less drought tolerant during hot and windy conditions. Raised beds are the perfect solution for gardening in wet climates plagued by clay soil.
Benefits of Gardening in Raised Beds
- Control over the soil texture, nutrients and water levels (also referred to as soil tilth)
- Requires less need for chemicals – pesticides, herbicides and fertilizers
- Proper Drainage with a capital “D”
- Plant earlier in the season because the soil is less soggy
- Plant edibles closer together – that means higher yield and less space for weeds to grow!!!
- Requires minimal paths to maneuver around the garden. Less space need to grow a fixed amount of food. (note: this applies more to 4 x 10 foot boxed raised beds)
Words to Know: Soil Tilth
In short, soil tilth is the ideal soil composition – 50% soil and 50% pore space, with water and air equally distributed with the pore spaces. Learn more about Managing Soil Tilth from the Colorado State University Extension.
How to Build a Raised Bed with Rocks
Raised beds don’t have to be a row of multiple 4 x 10 foot boxes. Sure, you can grow more in less space and it’s easier to harvest crops and weed, but I wanted something a little more natural looking. Plus, this part of my yard is on a slight slope, and I didn’t want to deal with terracing wooden boxes.
The start of this project dates back to a sunny day in May 2006 (that’s how long I’ve been holding onto some of these DIY photos!). I decided to take on this project after 2 years of stunted plant growth and inevitable plant death caused by root rot. My plants were basically sitting in water for months at a time. Plants need water, but not THAT much water.
|Basalt wall rock||Garden Hose|
|Black french drain pipe||Wheelbarrow|
|Loam||Stakes and garden twine|
*I used 3/4″ open quarry for the rock wall base and to cover the french drain pipe. The quarry rock is great for creating solid bases, but I would recommend 1 1/2″ round river rock for drainage purposes. The round edges prevent rocks from wedging themselves into air pockets over time (defeats the purpose of water drainage).
1. I used a garden hose to shape the curve of the rock wall. I’m partial to curves because I think they break up all the square angles of a house, fences, property lot, raised beds and patios.
Gardens are Like Women, More Sexy with Curves – Jayme Jenkins, co-author of Garden Rules: The Snappy Synopsis of the Modern Gardener
2. Once I was happy with the shape, I used my shovel to remove about 18″ of dirt to make room for the rock base and french drain pipe.
NOTE: Many walls are built upon stamped dirt without a rock base. However, the weight of the rocks on top of my soggy, clay soil would have started to sink over time.
3. Now it’s time to bring in the wall rocks. After all was said and done, I only pinched my fingers between two heavy rocks twice.
4. I started with the larger, flatter rocks on the bottom to make a solid base. I stood a few of the larger rocks up on their side, just to change the lines up a bit. The first level was easy. Hand-picking the perfect rocks for the next couple of rows was by far the longest AND hardest part of this project (professional rock layers deserve every penny they earn).
5. Next I laid flexible french drain piping along the back of the wall and covered it with more rocks (this step is not pictured). My thought was to divert the water away from my lawn.
The late spring rains stall my progress for a few days, but this turned out to be a good thing. Now I could see how effective the french drain was at keeping puddles of water out of the lawn.
Well, the lawn was puddle-free, but the french drain ended up just displacing the water to another part of the yard (later this became a dry well and the problem was solved).
6. Since the space was so large, I back filled the dirt with loam (the perfect soil combination of sand, silt and clay). I later topped the soil with a 4″ layer of Blended Mint Compost. I prefer Blended Mint over bark-o-mulch because it looks good (a dark, almost black, color) and it’s nutrient rich.
Done! Now it’s time for planting.
Coming Soon: I’ll post more photos of this raised bed area where I installed stone pavers, plants, a container-planted Japanese Maple, galvanized pipes, Bob the buddha, and another mini raised bed.