What to Sow in September - Autumn in the UK Growing Guide.
September is one of the best months for resetting the garden. Soil often remains warm while rainfall becomes more dependable. That combination supports autumn lawn work, selected flower sowings and hardy salads.
What to sow in September
Sow flowers for future colour
Cornflowers, violas, and godetia can be sown during their autumn windows. Sweet peas can follow from October, so prepare deep pots and a sheltered, bright position now. Shop Flowers.
Autumn herbs and leaves
Rocket salad, salad leaf mixtures, cress and garlic chives can be sown this month. Keep outdoor sows clear of fallen leaves and sow only what you can use. Indoor herbs remain an option as daylight begins to fall. Shop Herbs.
Repair a lawn in September
September often provides good conditions for lawn seed: warm soil, lower evaporation and more regular rain. Remove leaves and debris, scarify only where there is a build-up of thatch or moss, loosen bare areas and sow evenly. Water if rainfall does not arrive. Shop Lawn Care.
| What to sow | Where to sow | What to expect |
| Rocket | Outdoors or under cover | Young leaves during autumn |
| Salad leaf mixtures | Outdoors or under cover | Autumn or overwintered crops |
| Cress | Bright indoor windowsill | Quick indoor harvest |
| Cornflowers | Outdoors in suitable conditions | Earlier flowers next year |
| Godetia | Sow indoors |
Earlier flowers next year |
| Viola | Sow indoors | Earlier flowers next year |
| Grass seed | Prepared outdoor soil | Germination before colder weather |
What should beginners stop sowing?
Avoid forcing tender crops that need a long, hot season. Tomatoes, beans and chillies started now are unlikely to make productive outdoor plants before cold weather. Focus on hardy or indoor options instead.
Beginner checklist for September
☐ Read the individual packet before sowing.
☐ Label every pot or row with the variety and date.
☐ Use containers with drainage holes.
☐ Keep newly sown compost moist, not waterlogged.
☐ Check the local forecast before moving tender plants outdoors.
Frequently asked questions
Is September a good month for grass seed?
Yes, it is often one of the most reliable periods, provided the soil is warm, moist and not waterlogged.
Can I sow wildflower seed shakers in September?
The Pronto planning rule for Seed Shakers is April to June after frost, so keep these for spring unless the individual pack states otherwise.
What can I sow indoors?
Cress, rocket salad, several herbs, bonsai and cactus projects can continue indoors.
Ready to start growing
Choose one or two manageable projects from this September list, follow the packet instructions and build confidence one sowing at a time.
Explore the linked Pronto Seed collections to find the varieties mentioned above.