When following biointensive gardening principles, the way to relieve compaction, improve drainage and promote deeper root growth is by double digging garden beds.
If you’re on especially sandy soil, you might be able to skip it. I’m on clay, which is why I double dig a couple of beds each spring for my potatoes.
By moving my potatoes every year, it ensures each part of my garden will get double dug at some point.
It’s hard work, but it makes a nice bed.
Here’s how to do it (Academy members, we cover this in month 1 along with many other aspects of preparing a garden bed):
Take a garden fork or spade and dig a 4-5 foot long trench, 12 inches (30 cm) deep, removing that soil off to the side.
Then use a garden fork to loosen the soil a further 12 inches in the bottom of that trench, which is why we call it ‘double digging’ the garden bed.
Next you dig a trench right beside the original, placing the soil from that new trench over in the original trench, and then again loosening the soil at the bottom of the new trench.
Do this all along your bed, perhaps placing some of the soil from your first trench into your final trench, saving the rest for your compost pile.
The reason I like double digging when building a garden is not only to loosen the soil, but also to incorporate compost and organic fertilizers.
What I would say about this deep soil penetration, though, is that it’s the ‘physics’ approach to improving soil structure, and adding compost is the ‘biology’ approach, and what’s missing in biointensive gardening is the ‘chemistry’ approach.
If you want your soil structure to stay in good shape without having to double dig it every year, you need to balance soil fertility by using appropriate mineral fertilizers, generally based on a soil test.
The counter argument to this is that soil testing and fertilizers cost money (true), aren’t available everywhere (true) and aren’t as sustainable (true).
All of these are excellent points, and when they are true for you, double digging your garden every year or every few years can help. This is the case when using more ‘physics’ in place of ‘chemistry’ makes sense.
It still doesn’t address your fertility imbalances, but it will help with your soil structure in the short term.
If you want to learn how to do the double digging technique, click the button below where I’ve shown it on video: