Gardening with Diarmuid Gavin: to dig or not to dig?
New thinking has challenged the tradition of digging over the garden for winter
Published 08/11/2015 | 02:30
We are fast approaching the digging season. Early winter - what we'll loosely say as being October to December - is commonly thought of as the best time to prepare soil. Traditionally, it has been believed that even rough digging in these months will be of great benefit to your garden as, when the frost comes, it will finish the job for you, breaking down the clumps and crumbs to a nice tilth.
Why do we dig and do we always need to? Well, there's a number of reasons.
We may want to clear the soil of weeds, especially the perennial type with tap or stringy roots such as dandelions, convolvulus and scutch grass. Or we might wish to aerate a heavy soil by allowing oxygen in. It might be that our soil needs conditioning, with the addition of humus material such as well-rotted manure, which will travel through the ground working its nutritious magic.
As if gardening didn't seem complicated enough, there's a couple of different types of digging.
Single digging is digging trenches to a spade's depth, turning the soil as you go along. Double digging is more labour-intensive but it's traditionally seen as doing a better job. It involves digging down two spades' depth and laying a trench of manure before replacing one spade's depth of soil on top of that. Over time this will certainly create a wonderful base for plant roots to explore.
This is a method often used for hungry fruit, vegetables or when planning a rose bed. It's also considered good practice when preparing the ground for a herbaceous border.
However, there's another school of thought that is gaining increasing traction over the years - not digging at all. This method of gardening revolves around respecting natural soil structures through appreciating and encouraging the chemistry, insects, worms and bugs which naturally inhabit our garden soil.
We only have to view the beauty of the untamed countryside to realise that natural vegetation does extremely well without our intervention. Contemporary thought among some scientists and gardeners is that digging can be quite destructive to the structure of our soil which has been formed over hundreds and thousands of years.
Soil is packed with vibrant life forms - earthworms, fungi, microbes and insects. Digging can destroy this delicate network which often functions very well without our intervention.
In many situations, by using organic humus material such as compost as a mulch on compacted or low fertile soil, productivity can be increased. It is an excellent solution for urban gardening and works especially well when combined with council or community-run composting projects.
However, there's certainly some instances where without digging we wouldn't achieve results. One example is when the soil is too heavy and needs conditioning to break down, and the addition of organic matter to free up all the nutrients and trace elements and make them available to roots. Another is when the soil is light and sandy and leaches out any available or added food.
A method I have been trying recently in a patch of the garden has proved interesting. I don't live too far from the sea, so I have been able to avail of harvested seaweed. The rain washes away excess salt and on ground that's fairly good I have been layering a mulch of seaweed over part of the border that has died down. Last year over the winter the seaweed did a wonderful job - it protected the roots of the plant from any frosts while also slowly breaking down itself and feeding plants loads of lovely goodies such as nitrogen, trace elements and amino acids. But the really striking thing was lifting some of the seaweed even in the middle of winter and seeing the enormous amount of earthworms busy working away, breaking down the soil digesting the seaweed and creating tunnels for the exchange of air and gases.
So, another option for you may be deciding to ditch the digging if your soil is relatively good and instead introduce a heavy mulch of organic material - seaweed if it's available, or a good blanket of well-rotted farmyard manure - and allow that to act in a more holistic way to condition your soil.
Just because traditionally our dads and granddads battered the soil with spades and forks, doesn't mean we have to today.
This week in the garden:
Continue to rake up the leaves and debris. Try to pick a good dry day for this — it makes for easier, cleaner, more satisfying work.
Plant out winter bedding such as violas, primulas and bellis (pictured).
Bare root plants will soon be available to purchase and plant. It’s an excellent and cheap way of planting young hedging plants and small trees. However, if there’s any frost after planting, the roots can be lifted out of the ground. So keep an eye on them and firm in well.
Cut back yellowing foliage from herbaceous perennials and throw on the compost heap.