Autumn jobs are easy to put off: the weather is still pleasant, the last tomatoes and peppers are ripening, and it feels as though there's time. But most of what follows has a hard deadline, after which doing it stops making sense — or the sooner it's done, the better the garden comes through to spring.
1. Harvest and clear plant residues
As soon as a crop is finished, take the foliage off. Healthy material (peas, beans, lettuce) can be chopped and left on the bed or composted; anything diseased — tomato blight, powdery mildew on cucumbers and courgettes — belongs in the household waste, because the spores won't die in an ordinary heap and the disease would come back next year.
2. Plant garlic for overwintering
October is the main window for planting garlic — early enough to root before winter, late enough not to push shoots above ground. It suits exactly those beds freed up by summer crops such as courgettes or tomatoes. The full method is in the guide on when to plant garlic.
3. Sow green manure on empty beds
A bed that won't be used again before winter shouldn't be left bare. White mustard or phacelia germinate even in cooler September weather, frost off by themselves over winter, and their residue protects the soil and enriches it by spring — with nothing further for you to do.
4. Put fallen leaves to use
Leaves aren't waste. Healthy ones make excellent mulch around perennials, shrubs and fruit trees, where they protect roots from frost over winter and break down gradually. Diseased leaves (leaf spot, mildew) should go away from the garden, not onto the compost or the beds — the disease would overwinter and return in spring.
5. Last mow and autumn feed for the lawn
The lawn gets its final cut about a month before the first expected frost, so it can recover and doesn't go into winter too short. An autumn feed with less nitrogen and more potassium strengthens roots rather than top growth.
6. Divide and move perennials
Late summer and early autumn beat spring for splitting overgrown clumps of perennials — the soil is still warm, so roots establish before winter, while the top growth has stopped and puts less strain on the plant.
7. Protect tender plants from frost
Young woody plants, roses and more tender perennials are worth earthing up and mulching with straw or bark around the base before the first frosts. Fussier subjects such as figs or hydrangeas appreciate a wrap of horticultural fleece as well — not plastic, under which condensation would do more harm than the cold.
8. Harvest and store vegetables for winter
Potatoes, carrots, squash and other storage crops are lifted before the first frosts and kept cool and dark. How to store each kind so it lasts as long as possible is covered in how to store the harvest.
9. Check and clean tools and the greenhouse
Before tools go away for winter, clean the soil off them and sharpen the blades of secateurs and spades — it makes spring work easier straight away. A greenhouse or polytunnel is worth washing out, especially if it had mildew or blight this year, so spores don't carry over into next season.
10. Plan next season
Autumn is the best time to write down what grew where this year — it's hard to remember in spring, and it's the foundation of crop rotation. It matters most for Solanaceae (tomatoes, peppers, potatoes) and cucurbits (courgettes, cucumbers, squash), where you want to know where they've been for the last 3–4 years before they return to the same spot.
Most of these jobs take an afternoon, but spread across the rest of autumn they can all be done without rushing. For what to actually sow and plant right now, see the monthly guides for September and October.
Frequently asked questions
When should garlic be planted in autumn?
Overwintering garlic goes in during October, roughly 4–6 weeks before the first sustained frosts, so it has time to root but not to push shoots above ground. In milder areas that means later in October, in colder ones earlier.
Is September too late to sow green manure?
No. White mustard and phacelia germinate even in cooler weather and make enough growth from a September sowing. They frost off by themselves before winter, so there's nothing to incorporate, and in spring you simply work the residue lightly into the soil.
What should I do with fallen leaves?
Best of all, don't throw them away. Healthy fallen leaves work as mulch around perennials and shrubs, where they protect roots from frost, or they can go on the compost. Diseased leaves (leaf spot, mildew) belong in the household waste, not the compost heap.
How do I protect plants from the first frost?
Tender perennials and young woody plants are earthed up and mulched with a layer of straw, leaves or bark around the base, which protects the roots. More tender species (fig, hydrangea, standard roses) are additionally wrapped in horticultural fleece or hessian.