Types of mulch
Just about any chipped, shredded or naturally fine plant material works as a mulch, but some are better suited to particular contexts than others. Unfortunately, whatever the type, finding a supplier usually takes a bit of local searching or networking.
1 Clean wood chip
Neat in appearance and long-lasting, this is the mulch of choice for paths and traffic areas. It works fine in beds and is perfect for use around indigenous plants. It won’t add nutrients and improve soil texture as fast as mulch with green material. Over time it changes colour from brown to silvery grey and it lasts many years, especially if applied thickly. It can be hard on bare feet compared with other options. Usually a sawmill by-product, it’s often only available in bulk – landscapers and nurseries may know of suppliers. Make sure it’s made of untreated wood.
3 Chipped whole branches
Chipped whole brances from tree felling and plot clearing is the perfect allpurpose mulch but can vary significantly in texture and composition. The fine leafy content rapidly breaks down to feed and build soil within a year, while the woody component sticks around for longer and also contains more soil-building nutrients than pure wood chip. Chipped wattle and other nitrogenfixing invaders are one of the best options for veg gardens. Ask at tree-felling or bulkcompost companies. It used to be an unwanted by-product and could easily be had free of charge to save a trip to the dump, but these days it’s in high demand. Municipal waste sites with garden refuse facilities usually have mulch available for collection at no cost or low prices, but it may contain weed seeds and litter.
2 Nursery mulch in bags
Wood chip, peach pips and pine bark are commonly available but it’s expensive and has a big plastic-packaging footprint, so it’s not really practical except for tiny gardens. Rather find a bulk supplier and mulch properly. Fine mulch like rooibos-tea waste can be a superb option for pots and containers, though.
4 Gravel and rock
I’m not a fan of gravel as a landscaping solution or garden mulch. It does conserve soil moisture but has to be laid on top of a non-biodegradeable, nonrecyclable weed-and-soil barrier geotextile fabric and prevents any organic soil building below. Somehow, gravel always ends up mixed in with soil and a once-pristine surface accumulates soil and weeds, and stones spread shabbily into everything.
Whereas plant-based mulch breaks down into rich humus, old gravel contributes nothing to the soil and usually makes a mess that’s hard to clean. Coarse rock or pebbles without a geotextile barrier is much more sensible as a really low-maintenance option for sidewalks, around established trees and succulent gardens or as a landscaping feature. Unlike gravel, rock mulch is easy to weed and garden around, and can be easily removed.
Very fine stone can be a useful mulch for succulent plants in pots that prefer soil with a low organic content, stopping pots from getting too hot and preventing moisture loss.
5 Scavenged mulch
Neatly chipped mulch is lovely, but any fine plant material is beneficial as a soil cover. Of course, it’s important to avoid importing weeds and undesirable grasses that have already made seed heads. Be especially careful in late spring to summer. But there’s a surprising amount of clean, weed-free prime mulch being thrown away in suburbs, verges and parks everywhere. I keep a few empty feed sacks in my car, and fill up on any of these when I find them: • Pine needles – they won’t make your soil acidic unless applied for years. • Grass cuttings and waste straw or hay Long weed-free cut grass doesn’t last long but is a great soil builder. Mowed lawn clippings are usually not recommended as mulch as they can mat and prevent water penetration, but are fine scattered quite thinly. • Fallen leaves have a tendency to blow around and mat, but that can be prevented by mixing them with coarser mulch, shredding them coarsely, or just putting them loosely in a sheltered spot where they won’t be walked on. • Tree-stump removal by grinding machines produces fine and soft shredded wood. Its low initial soil-nutrient value means it’s not a great idea for vegetables or soil that needs rapid improving, but it makes a great weed-suppressing ground cover or soft path.