What to Plant in September UK

What To Plant In September UK

In September in the UK, sow winter salads, spinach, spring onions, overwintering onions, broad beans in mild areas and green manures outdoors. Start lettuce, herbs, oriental leaves and microgreens under cover. Plant spring cabbage, hardy salads, overwintering onion sets and garlic later in the month.

SoilCommander Editorial Team

UK vegetable growing guides · Checked against RHS & Met Office guidance

Every SoilCommander guide is written and maintained by our editorial team for real UK growing conditions, and reviewed against Royal Horticultural Society growing advice and Met Office climate data before publication.

11–17°C

Average UK temperatures in September

Oct–Nov

When first frosts arrive in most UK regions

6°C

Minimum soil temp — outdoor sowing window closing

September is a month of transitions in the UK vegetable garden — summer crops winding down, overwintering ones going in, and the soil still warm enough to make late sowings worthwhile.

September is a transition month: harvest summer crops, protect late crops, clear finished beds and start planning autumn and winter cover. Use the UK Vegetable Garden Planner PDF to record what grew where before the season fades from memory.

September Planting Preview

September UK vegetable harvest with tomatoes beans courgettes potatoes carrots and beetroot — September is the handover month: harvest summer crops, sow hardy follow-on crops and record which beds need autumn cover or rotation notes.

September Planting Quick Table

Job	Good September options	Notes
Sow outdoors	Winter salads, spinach, spring onions, overwintering onions, broad beans in mild areas and green manures.	Keep seed beds moist and protect young salads from slugs and cold snaps.
Start under cover	Lettuce, herbs, oriental leaves and microgreens.	Use modules, trays, windowsills, cold frames or a greenhouse for more reliable germination.
Plant out	Spring cabbage, hardy salads, overwintering onion sets and garlic later in the month.	Do not plant garlic or onions into waterlogged soil.
Harvest now	Tomatoes, beans, courgettes, potatoes, carrots, beetroot, late salads and herbs.	Check tender crops before nights get colder.

September Garden Jobs

Clear finished crops and compost healthy plant material.
Protect late harvests from cold nights and wet weather.
Sow green manure where beds will otherwise sit empty.
Plant overwintering onions in suitable, free-draining soil.
Record crop rotation notes before clearing beds.
Check courgettes, squash and cucumbers for powdery mildew.

What To Harvest In September

September harvests can include tomatoes, beans, courgettes, potatoes, carrots, beetroot, late salads and herbs. Lift potatoes when plants are ready, keep picking beans while pods are usable, and bring tender crops under control before colder nights slow growth.

Common September Mistakes

Leaving tender crops outside too long without watching night temperatures.
Delaying overwintering onions until soil is too wet or cold.
Leaving cleared beds empty instead of sowing green manure or planning cover.
Forgetting to record what grew where for crop rotation.
Ignoring powdery mildew on tired courgettes, squash, cucumbers and peas.

Useful September Links

Frequently Asked Questions

What vegetables can I plant in September in the UK?

In September, UK gardeners can sow winter salads, spinach, spring onions, overwintering onions, broad beans in mild areas and green manures. You can also plant spring cabbage, hardy salads, onion sets and garlic later in the month.

Can I plant onions in September?

Yes. RHS guidance confirms overwintering onion sets are commonly planted in autumn, including September in suitable conditions, so they can establish before winter.

Can I sow spinach in September?

Yes. Spinach can be sown in September for autumn and overwintering crops, especially with protection in colder areas.

Can I sow broad beans in September?

Broad beans are usually more common from October or November, but September can work in mild areas if the soil is suitable and plants do not become too soft before winter.

What should I harvest in September?

Harvest tomatoes, beans, courgettes, potatoes, carrots, beetroot, late salads and herbs. Keep an eye on tender crops as nights become cooler.

Should I sow green manure in September?

Yes, September is a useful time to sow green manure on empty beds so soil is covered through autumn and winter.

Last updated 4 July 2026

Relevant next steps

Turn This Month's Jobs Into A Plan

Month-by-month advice works best when it becomes a written sowing list, bed plan, and follow-up task list.

Printable UK garden plannerRecord this month's sowing dates, crop rotation, and bed tasks. Seed starting setupChoose trays, labels, compost, and indoor sowing tools before you start. Full planting calendarCompare this month with the rest of the UK growing year.

Plan the next step

Use the printable UK Vegetable Garden Planner to turn this guide into sowing dates, bed layouts, and weekly garden tasks.

Get Planner

What To Plant In September UK