Raised beds are wonderfully generous in summer, but their exposed sides and free-draining mix mean they feel the cold more keenly than ground-level soil. A little attention now, before the worst of the weather arrives, will pay you back handsomely when spring comes round and you want to sow straight into a crumbly, weed-free bed.

Why Raised Beds Need a Different Approach

Because the soil sits above ground level, it is exposed to wind and frost on all four sides. That means it warms up quickly in spring — a real advantage — but it also chills faster in winter and dries out more readily in a dry spell. Winter rain also washes soluble nutrients, particularly nitrogen, down through the profile and out of reach of next year's seedlings.

Left bare through the colder months, the surface can cap and pan, and every gap becomes an invitation to chickweed, bittercress and annual meadow grass. The goal over winter is simple: keep the soil covered, keep it alive with organic matter, and avoid compacting it.

Clear Out Spent Crops

Start with a thorough tidy. Pull up spent tomatoes, courgettes, cucumbers, beans and any tired salad plants. Remove the debris rather than leaving it lying about, as slugs, snails and overwintering pests will happily use it as a hotel.

• Bin diseased material. Tomato and potato foliage with blight, brassicas with clubroot, and anything mildewed should go into the council green waste or general rubbish — not your compost heap.
• Compile healthy material. Disease-free stems and leaves can go into the compost bin, chopped small so they rot down faster.
• Leave what earns its keep. Leeks, parsnips, kale and winter salad can stay put, and a few seed heads left standing will feed the birds.

Resist the urge to dig the bed over. Forking through wet, heavy soil destroys its structure and creates a solid pan beneath. If you need to loosen it, wait for a dry, frost-free day and use a fork gently, working backwards so you never stand on the soil you've just improved.

Feed the Soil, Not the Plant

Once the bed is clear, spread a generous layer of well-rotted organic matter across the whole surface — around five to eight centimetres is about right for most beds. Horse or cattle manure that has been stacked for at least six months, homemade compost, or mushroom compost all work well. If you garden on clay or heavy soil, this is the single most valuable thing you can do all year.

Simply lay it on top and leave the worms to pull it down. They will work it into the soil right through until spring, aerating as they go and feeding the microbial life that makes nutrients available to plants. There is no need to dig it in, and doing so would only undo the structure you have been building.

If your soil tends to be acidic and you plan to grow brassicas next year, this is a sensible moment to apply a sprinkling of lime, following the rate on the packet. Otherwise, leave the pH alone until you've tested it.

Mulch the Surface

A mulch is the blanket that ties everything together. On top of your compost, add five to seven centimetres of a lightweight, fibrous material. Leaf mould is ideal, and if you have a few bags quietly rotting down in the corner, this is exactly what they are for. Straw, spent hops, bark fines or just a thick layer of garden compost all do the job.

• Spread evenly right to the edges of the bed, so no bare patches are left to grow weeds.
• Keep mulch clear of plant crowns — leeks, garlic and overwintering herbs — to avoid rot in wet weather.
• Don't mulch waterlogged ground. If the bed is sitting wet, wait for a drier spell, or the mulch will simply seal in the damp.

If a bed is completely empty until spring, you could sow a green manure such as field beans, winter tares or grazing rye. It holds the soil together, soaks up rain, and can be cut down and left on the surface as a mulch in March.

Check the Structure and Drainage

Autumn is the moment to give the bed itself a once-over. Walk the edges and look for timber that has started to rot, loose screws or boards that have shifted with the frost. A quick repair now saves a rebuild later. Check that any drainage holes or gravel-filled bases are still clear, and cut back any weeds that have crept over the sides.

Finally, protect the soil from compaction by never walking across the bed. Keep a sturdy plank at the end of the plot and stand on that when you need to reach further in. Tread lightly, cover generously, and the bed will be ready and willing when the growing season returns.