Using Woodchip for Soil Health, Mulching & Composting

Jane Westoby
Mar 27
3 min read

Updated: Apr 23

If you’ve ever wondered whether that pile of woodchip sitting in your garden is worth keeping, this one’s for you.

In this week’s podcast, I’m joined by Ben Raskin, Head of Agroforestry at the Soil Association, author of The Woodchip Handbook, and a passionate advocate for low-intervention, regenerative growing.

We talked all things woodchip—what it is, why it matters, and how to use it to transform your soil health (without digging a thing). As someone who already uses woodchip around my own garden, I knew there was more to the story—but I had no idea how powerful it really was until this conversation.

What is Woodchip?

At its simplest, woodchip is chipped or shredded tree branches. But as Ben explains, not all woodchip is created equal. There are several types:

Bark chip – a by-product of timber milling, great for paths but low in nutrients.
Mixed woodchip – the mix of branches, leaves, and trunk, typically left behind by tree surgeons.
Ramial woodchip – made from young branches under 7cm thick. This type is nutrient-rich, full of life, and ideal for building soil health.

This young, twiggy woodchip, which we often get from pruning or tree surgery, is absolutely bursting with potential.

“The bark is where all the nutrients are… the more young wood you have, the more useful the chip is—even fresh.” – Ben Raskin

How Woodchip Enhances Soil Health

One of the biggest takeaways from our discussion was just how effective woodchip is at building soil life, particularly fungi. Most cultivated soils are typically low in fungi because fungi dislike being disturbed. Woodchip feeds fungal networks, which in turn improve soil structure, help retain moisture, and make minerals more accessible to plants.

“It’s like fast food for fungi,” Ben says. “All those cut ends in the chip make it easier for fungi to move in and start breaking it down.”

That decomposition process does not only feed fungi; it attracts the entire soil food web: bacteria, nematodes, earthworms, and more. It’s slow-release, long-term soil building at its finest.

Moisture Retention and Soil Structure

Adding woodchip as a mulch doesn't just build soil health—it can also save you on watering. Ben shared trials showing that mulching with woodchip can reduce watering needs by up to 25%, especially during dry spells. Moreover, soils with regular woodchip mulch become more sponge-like: they drain better when it’s wet and hold onto moisture when it’s dry.

Practical Applications of Woodchip in the Garden

You don’t need to dig it in. In fact—don’t! Simply mulch it on top and let nature work its magic. Ben recommends using woodchip in three key areas:

Paths – This is a straightforward win. Woodchip suppresses weeds and looks great.
Around trees and shrubs – Apply a deep layer (even 25cm!) for long-term weed control and moisture retention.
In established borders – Perfect for building structure over time.

If you're growing shallow-rooted vegetables or seedlings, it's advisable to compost woodchip first or mix it with grass clippings or manure to avoid nitrogen lock-up.

Sourcing Woodchip

If you’ve got trees, you might already have a resource at hand. If not, Ben suggests some alternatives:

Connect with local tree surgeons – many still pay to dispose of chip.
Try Arbtalk – a website where you can register as a drop-off location.
Ask your allotment association – many organise shared chip deliveries.
Buy in bulk – 1m³ bags are available online, though they can be pricey.

“Any woody growth in your garden is your fertility. If you send it away, you’re losing a free resource.” – Ben Raskin

Learn More About Woodchip

Ben’s book, The Woodchip Handbook, is loaded with real-world case studies, field trials, and surprising uses for woodchip—from propagation compost to disease-resistant mulch. It’s essential reading for anyone wanting to elevate their garden soil.

👉 Buy the book from Chelsea Green Publishing or message Ben directly for a signed copy!

🎧 Listen to the Episode

This episode is a brilliant listen—informative, funny, and completely inspiring. I came away with a whole new appreciation for this "waste" material. I think you will, too.

👉 [🎙️ Click here to listen now on your favorite podcast app]