How do I improve my soil?

Soil improvement sounds like it should be complicated and mostly isn't. The dominant factor is organic matter, which improves structure regardless of what you started with. Digging it in is optional; spreading it on top and letting worms do the work is easier and does less damage to soil structure.

What you'll need

• Well-rotted compost or manure
• Spade and fork
• Wheelbarrow
• Soil pH test kit (optional)

Step by step

1. Identify your soil: squeeze a moist handful.Sticky and holds a shape: clay. Gritty and falls apart: sand. Smooth and holds together loosely: loam.
2. Test the pH if plants have been doing badly for no obvious reason.Most vegetables want 6.0–7.0. Cheap test kits are adequate for this decision.
3. Spread 5–8cm of well-rotted organic matter on the surface each autumn or spring.Compost, well-rotted manure, leaf mould or spent mushroom compost. Consistency over years matters more than the exact material.
4. Leave it on the surface as mulch rather than digging it in.Worms incorporate it, which preserves soil structure and the fungal networks digging destroys.
5. For heavy clay, add organic matter and consider coarse grit for permanently wet areas.Never add sand to clay in small quantities — the combination can set harder. Grit and organic matter are the reliable route.
6. For sandy soil, add as much organic matter as you can, more often.It breaks down faster in sand, so this is an annual job rather than an occasional one.
7. Avoid walking on beds, especially when wet.Compaction is a major cause of poor soil, and it's entirely avoidable with a path or a plank.
8. Keep the soil covered — with plants, mulch or a green manure over winter.Bare soil erodes, compacts under rain and loses nutrients.

Tips

• Making your own compost is the cheapest route to a continuous supply. See the composting guide.
• Leaf mould is free: pile fallen leaves in a bin bag with a few holes and leave it for a year. It's an excellent soil conditioner.
• Fresh manure will scorch plants and can carry weed seeds. It needs to be well-rotted — at least six months, ideally a year.
• Soil improvement is cumulative. Three years of mulching transforms a difficult bed in a way one heavy application never will.

Common mistakes

• Adding sand to clay soil — In anything less than enormous quantities it can make the structure worse rather than better.
• Digging every year — It damages soil structure and fungal networks. Surface mulching achieves more with less work.
• Using fresh manure — It scorches roots and can carry weed seeds and residual herbicides. Well-rotted only.
• Leaving soil bare over winter — Rain compacts it, nutrients leach and weeds colonise it.

Questions people ask