Start by Clearing What's Finished

Nothing improves a plot like bare, tidy ground in late autumn. Begin with the crops that have done their job. Once the last runner beans have been picked and the courgette plants are mildewed and sulking, cut the stems at ground level and add the soft growth to the compost heap. Leave the roots of beans and peas in the soil — they carry nitrogen nodules that will feed whatever follows.

Courgettes, cucumbers and squashes are best lifted whole, as they have a habit of spreading grey mould once the nights turn cold. Brassica stalks are tougher: chop them up before composting, or the heap will fill with woody stumps that take years to rot. Tomato plants should go in the green waste collection rather than your own compost, since blight spores and virus can survive a domestic heap that never gets hot enough.

As you clear each bed, pull any perennial weeds — couch grass, bindweed, ground elder — by hand, getting as much of the root out as you can. Every fragment left behind becomes a new plant in March. This is the one job worth doing slowly.

Feed the Soil While It's Still Warm

The soil is still warm through October on most plots, which means worms and microbes are active and will start working organic matter into the ground straight away. Spread well-rotted manure or garden compost at roughly a barrowload per square metre — a layer about 5cm to 7cm deep — over any bed that will be empty until spring.

• Clay soils: add plenty of bulky compost and leave it on the surface. It will be drawn down by worms over winter, improving drainage without turning the plot into a bog.
• Sandy soils: compost is your main tool for holding moisture and nutrients. Add it now, and again in spring if you have enough.
• Heavy or compacted ground: dig it roughly, leaving the surface in big clods for the frost to break down. Don't be tempted to till it fine — frost does that job better than any fork.

If you garden no-dig, simply lay the compost on top and let the worms do the rest. Either way, don't lime and manure the same bed at the same time; lime where brassicas are going, manure where beans, peas and potatoes will follow.

Sow Green Manure on Empty Beds

Any bed you won't use until April should never sit bare. Winter rain washes nutrients straight through the soil, and bare ground grows weeds faster than anything you plant deliberately. Green manures cover the soil, hold on to nitrogen and add organic matter when you dig them in.

• Grazing rye: sow by mid-September in the north, by early October in the south. Extremely hardy, brilliant on heavy soil, but dig it in before it sets seed.
• Winter tares: a legume that fixes nitrogen. Sow September to early October and cut it down in March before flowering.
• Field beans: tough, deep-rooted and useful for breaking up clay. Sow from October onwards.
• Phacelia: tender, so only worth sowing where you have a mild autumn, but the bees adore it and it dies back with the first hard frost.
• Mustard: quick to establish, but avoid it on beds where brassicas are going next, as it shares their pests and diseases.

Broadcast the seed thinly, rake it in, and water if the weather stays dry. A green carpet by November is exactly what you want.

Protect Structure and Get Ahead on the Small Jobs

Autumn is also the time for the little tasks that save hours later. Rake fallen leaves into a wire bin or old compost bags — a year from now you'll have leaf mould, the finest soil conditioner there is, and it costs nothing. Clean and stack your canes and netting, empty pots and store them dry, and give the greenhouse glass a wash so winter light gets through.

Check paths and edging too. Boards lifted by summer growth can be knocked back into line now, and a quick hoe along the plot edges stops weeds creeping in over winter. If you have raised beds, top them up with compost before the frosts arrive, so the material settles over the winter months.

Finally, plant for next year while the soil is still workable: garlic goes in from November to December, overwintering onions in October, and hardy broad beans like Aquadulce Claudia can go in late October in milder areas for the earliest crop of the following summer.

Plan the Rotation While It's Quiet

With the beds clear and the light fading early, sit down with a mug of tea and sketch next year's plan. Rotate your groups — brassicas, roots, potatoes, legumes and onions — so no family returns to the same ground for at least three years. That single habit prevents most of the clubroot, white rot and eelworm problems that plague untended plots.

Note what did well and what didn't, and where you had gaps. Order seed early, before the varieties you want sell out in January. Do these autumn jobs now, while the ground is warm and the days still have some sun in them, and spring will find you with clean beds, healthy soil and a head start on the season.