We say it, we repeat it, and yet so many gardens remain with bare soil between plants: mulching is perhaps the simplest, most economical and most effective gardening technique there is. A layer of material placed on the soil, and a whole cascade of benefits kicks in.
The 4 key benefits of mulching:
- 💧 Limits water evaporation
- 🌱 Slows down weeds
- 🌡️ Regulates soil temperature
- 🪱 Feeds soil life
Why bare soil is the gardener's enemy
In nature, bare soil hardly exists. Vegetation and leaf litter permanently cover the earth, protecting it from sun, driving rain and drying wind. Soil left bare loses its moisture, compacts under raindrops, and its biological life quickly impoverishes.
By imitating what the forest does naturally, mulching recreates a favourable micro-environment: the soil stays cool and loose, earthworms thrive, and mycorrhizal fungi — those invisible allies of roots — can weave their networks undisturbed.
"Nature never invented the spade. It invented dead leaves. Take a leaf out of its book."
Organic or mineral mulch: which to choose?
There are two main families of mulch, with distinct uses and effects. The choice depends on your type of planting, your soil and your objectives.
Organic mulches
- Wood chips / RCW
- Shredded dead leaves
- Cereal straw
- Dried grass clippings
- Coarse compost
- Cocoa or buckwheat shells
Mineral mulches
- Decorative gravel
- Crushed slate
- Volcanic pozzite
- River pebbles
- Expanded clay balls
Organic mulches have the advantage of slowly decomposing and enriching the soil with humus — ideal for perennial beds, vegetable gardens and fruit trees. Mineral mulches don't degrade and are perfectly suited to Mediterranean plants and dry gardens, where excess moisture would be harmful.
⚠️ To avoid: Synthetic mulching fabrics (black geotextile) seem practical but prevent soil gas exchange, block earthworms and end up tearing. Always prefer natural materials.
How to mulch correctly: step by step
Mulching is simple, but a few basic rules make all the difference between effective mulching and mulching that creates problems.
- Weed first the soil to be mulched. Mulch slows unwanted weeds but doesn't eliminate them if they're already present.
- Water if the soil is dry before laying mulch. The goal is to conserve existing moisture, not to waterproof already dried-out soil.
- Apply a thickness of 5 to 10 cm minimum. Below 5 cm, weeds easily break through. Above 15 cm, the soil may suffer from lack of oxygen.
- Leave a free space around stems and trunks (3 to 5 cm). Mulch in contact with wood encourages fungal diseases and rodents.
- Renew each spring for organic mulches that have decomposed, or top up if thickness has decreased.
💡 RCW, champion of all categories: Ramial Chipped Wood (chips from small fresh branches) is the most beneficial organic mulch for soil: rich in lignin and fungi, it stimulates microbial life and durably improves soil structure. Get it free from tree surgeons in your area.
When to mulch and where?
Mulching is useful all year round, but two moments are particularly strategic: spring, before heat and drought set in, and autumn, to protect roots from frost and enrich the soil during winter. In summer, mulch in place can save up to 70% of watering.
As for priority areas, start with the vegetable garden (immediate water and weeding time savings), perennial beds (less watering, more flowering), then tree and shrub bases, often neglected when they benefit enormously from good mulch.
The gardener's most profitable gesture
Mulching means working less to get more. Less watering, less weeding, fewer interventions on the soil — and in return, more vigorous plants, more living soil, and a garden that resists weather variations much better.
If you could adopt just one habit in your garden this year, this would be it. Cover the soil, and let nature do the rest. 🌱
