In this lesson we’re going to show you how to double dig.
Double digging aims to work the soil 60 centimeters, or about two feet, deep. That is twice the depth of single digging.
This aims to loosen the soil’s structure in order to expand root growth, air, gas and nutrient exchanges to deeper depths.
Double digging is ideally done during the spring or autumn.
To begin double digging, you will need: digging fork, a border spade, a hand fork, a rake, a few 20-liter buckets, a wooden board, a wheelbarrow and an irrigation system.
Start by stringing off the area where you’re going to double dig.
This will optimize your work and keep your bed straight.
Weed if needed.
Check the moisture level in the soil and water it if necessary.
Place the wooden board 30 centimeters, or one foot, away from the beginning of the bed.
That's about the size of the border spade's head.
We’re using the wooden board to avoid any soil compaction.
Now place the buckets at the beginning of the bed.
Step 1: Take the soil out of the first trench and dump it into the buckets.
Scrape the soil from the bottom of the trench like this.
We now have a trench that’s 30 centimeters, or about one foot, deep, which is about the size of the border spade's head.
The soil in these buckets will be used at the end of the double digging process to fill the last trench.
Step 2: Now use the single digging technique at the bottom of the trench.
Insert the digging fork 20 centimeters, or about 8 inches, away from the bed’s edge and dig throughout the entire trench.
Once you arrive at the end of the trench, turn the fork to facilitate the last movement.
Step 3: Move the wooden board back 30 centimeters, or one foot.
Repeat the first step, but instead of dumping the soil into the buckets, dump it into the first trench.
Note that we don’t mix the soil from different horizons. The topsoil should remain on top.
This is very important since most of the microbial life in the soil thrive within the first 20 centimeters (8 inches).
Repeat the previous steps until you reach the end of the bed.
Step 4: Rake the bed every 5 trenches.
You can make the bed flat or raised.
This step will reduce the amount of soil you’ll have to move at the end of the process.
We're almost to the end of the bed.
Repeat steps 1 through 3 one last time.
Once you arrive at the end of the bed, you only need to fill the last trench.
At this point, you have two options.
The first is to fill the trench with topsoil using the rake, like this.
Double digging brings air into the soil, which increases its volume. This is why raking the topsoil is often enough to fill the last trench.
If this is not enough, you can dump the soil in the buckets from the first trench.
Now, level the bed to give it its final form.
The remaining soil can be used for compost or flat soil.