September is the garden's turning point: summer's abundance is winding down, and the quiet work of autumn begins — planting garlic, sowing broad beans for overwintering, clearing the last summer crops, and mulching every empty bed. The gardeners who work steadily through September are the ones harvesting first next spring.
Here is exactly what to do this September in Central and Western Europe, in priority order. Published in late October so you can plan ahead — read it now, and arrive in September knowing precisely what to do instead of guessing. And a small milestone: this completes our full twelve months of checklists — every month of the gardening year, covered.
| Job | Why now | How |
|---|---|---|
| Plant garlic | Needs winter cold to bulb up properly | Plant cloves 15 cm apart, tip up |
| Plant autumn onion sets | Establish before winter; early crop | Sets barely covered, in well-drained soil |
| Sow broad beans for overwintering | Hardy varieties survive; crop weeks early | Sow direct, 'Aquadulce Claudia', sheltered spot |
| Clear spent summer crops | Frees beds for autumn work | Compost healthy foliage; bin diseased |
| Mulch empty beds | Protects soil all winter | Thick compost or leaf mulch everywhere |
| Last sowings | Final chance for quick crops | Spinach, radish, spring onions, lamb's lettuce |
| Lift tender crops | First frosts can strike any time | Harvest pumpkins, sweetcorn before frost |
Step 1: Plant garlic — September into October is the window
Garlic must be planted in autumn: the cloves need the cold of winter to trigger proper bulb formation — spring-planted garlic makes small, disappointing heads. Split bulbs into cloves and plant each 15 cm apart, tip up, about 5 cm deep, in the sunniest, best-drained spot you have. See our garlic growing guide for the full method.
Choose hardneck varieties for the best flavour (and the edible flower scapes in spring) or softneck for the longest storage. In heavy, wet soil, plant into a low ridge so water drains away — wet winter soil rots garlic faster than cold does.
Step 2: Plant autumn onion sets and shallots
Autumn onion sets planted in September establish roots before winter and race away in spring, cropping weeks before spring-planted sets. Plant them barely covered — just the tip showing — in well-drained soil, 10–15 cm apart. Our autumn onion guide covers varieties and timing.
Autumn shallot sets go in now too, in a sheltered spot. In very cold, wet areas, spring planting is safer for both — but in most of Central and Western Europe, autumn planting wins on earliness and size.
Step 3: Sow broad beans for overwintering
September is the moment for overwintering broad beans: sow a hardy variety like 'Aquadulce Claudia' direct now, and the plants overwinter small and crop in May — weeks ahead of spring sowings. Choose a sheltered, well-drained spot; cold and waterlogged is the combination that kills autumn sowings.
Sow a little more thickly than in spring to allow for winter losses, and do not fuss over them — they want to be ignored until March. If your garden is exposed or your winters harsh, skip it and sow in February instead; there is no shame in the reliable option.
Step 4: Clear the summer crops — compost the good, bin the bad
September clears the stage: pull spent beans, exhausted courgettes, finished sweetcorn and any diseased plants. Compost the healthy foliage (see our compost guide) and bin — never compost — anything diseased, especially blighted potato or tomato foliage (see our blight guide).
Leave the roots of beans and peas in the soil — the nitrogen-fixing nodules feed whatever follows. Chop the tops for the compost and let the roots rot down undisturbed.
Step 5: Mulch every empty bed — winter protection starts now
Every bed not holding a crop gets mulched thickly: compost, well-rotted manure, or fallen leaves, 5–10 cm deep. Our mulching guide covers the materials; the principle is simple — bare winter soil loses nutrients to rain, compacts under downpours, and grows weeds, while mulched soil arrives in spring dark, crumbly and alive.
Alternatively, sow green manures on beds empty for months — winter rye and field beans sown in September still establish well. Mulch or green manure, never bare soil: that is the September rule.
Step 6: Last sowings and last harvests
September still offers quick wins: spinach, radishes, spring onions and lamb's lettuce sown now crop before winter or overwinter small for spring. It is the last sowing month — after this, the seed packets rest until February.
And watch the forecast: the first frosts can arrive any time now. Harvest pumpkins, sweetcorn and the last butternut squash before the first hard frost — frost damages their skins and ruins storage. Green tomatoes picked before frost ripen indoors on a sunny windowsill.
Troubleshooting: September problems
Garlic rotting in wet soil: Planted into waterlogged ground — the classic autumn failure. Next year, plant on ridges or in a raised bed, and choose the sunniest spot. Cold is fine; wet is fatal.
Broad beans sown now going leggy and flopping: Sown too early in rich soil, or too thickly. September sowings should stay small and stocky going into winter — if yours are lush and tall, they were sown too early or fed too much.
Slugs shredding autumn sowings: September's damp nights are peak slug season — protect with cloches for the first weeks, patrol with a torch, and see our slug and snail guide.
Frost caught the pumpkins: Harvest immediately — lightly frosted fruits may still store if the skin is unbroken, but use them first. Next year, watch September forecasts like a hawk from mid-month.
What to do this October
Reading this in late October? Good news — nearly every September job still works in October. Garlic and autumn onions can still go in (garlic planting runs into November); broad beans can still be sown in mild areas; mulching is even more urgent now. The one thing you have missed is the last sowings — those truly needed September.
Use the full October checklist to catch up, and take a moment to appreciate the milestone: with September done, our twelve monthly checklists cover the entire gardening year — January's planning through December's quiet. Bookmark the set and you will never wonder "what should I be doing now?" again.
Frequently asked questions
Is September too late to plant garlic?
No — September through November is the garlic window in Central Europe. October is arguably the sweet spot; September planting is fine, just avoid waterlogged spots.
Hardneck or softneck garlic — which for beginners?
Hardneck for flavour and the bonus scapes; softneck for longest storage and braiding. Both grow the same way — plant in autumn, harvest in summer.
Can I still sow green manures in September?
Yes — September is excellent for winter rye, field beans and crimson clover. Sow as each bed empties; every week of autumn growth is free fertility.
When should I lift the last tomatoes?
Before the first forecast frost — green fruits ripen indoors on a windowsill or in a paper bag with a banana. Do not leave them out hoping; one frost ruins the lot.
Related guides
- August Garden Checklist: What to Do Now (Europe) — last month's harvest season
- How to Grow Garlic at Home: Beginner's Guide — this month's essential planting
- How to Grow Broad Beans at Home: Beginner's Guide — the overwintering sowing
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