Digging over in autumn? What the spade really does to your soil
Many gardeners dig every bed over in October simply because that's how it's always been done. Here's when it makes sense and when you can skip it.
Autumn digging has a good reputation, but it isn’t the best choice for every soil. Knowing what happens underground when you turn it over helps you decide where you need the spade and where you don’t.
What happens underground when you dig
When you turn the spade, the top layer ends up at the bottom and the bottom layer on top. The fine structure that earthworms, fungal threads and roots have built up over years gets torn apart. Soil life adapted to darkness, or to the oxygen near the surface, suddenly finds itself in the wrong place.
It isn’t quite as dramatic as it sounds: soil recovers. But turning it completely every year takes its toll, and it’s a lot of work for you, too.
Where digging still makes sense
On heavy clay soil, coarse digging in autumn can help. Leave the clods large, because winter frost breaks them apart, and by spring they crumble almost by themselves into a fine surface. For a new bed, such as turning lawn into a vegetable patch, you’ll usually need to dig once as well.
On loose, sandy or already well-kept soil, the spade adds little. The soil loses a lot of moisture there, and humus breaks down faster.
Loosen instead of turning
A digging fork loosens the soil without turning it. You push the fork in, rock it back slightly and pull it out again. Compacted spots break open, but the layers stay where they are.
It’s quicker than digging and easier on your back. Where there was a lot of walking or kneeling over the summer, it’s often all you need.
Don’t leave the soil bare in winter
Whether you dig or not, an open bed is exposed to rain, wind and frost over winter. Nutrients wash out and the surface turns to mud. A layer of mulch from leaves, grass clippings or straw protects the soil. Only the coarse clay clods stay uncovered, because you want the frost to break them apart.
End of September is already late for a green manure. Phacelia and buckwheat are not frost-hardy and die off in winter, and sown now they will hardly get going. You can still sow winter rye until about mid-October, and it keeps the soil rooted over winter. Otherwise, a thick mulch blanket does the job, too.
Try it on one bed
You don’t have to change your whole garden. This year, leave one bed undug, just loosen it with the fork and cover it. Treat the neighboring bed as usual. Next summer you’ll see for yourself where the plants grow better and where the soil is looser.
In Rootivo’s garden journal you can record which bed was treated how, and look back later to see what worked better.