What to Sow in September – Seeds to Plant in September in Ireland
September marks the beginning of autumn, but it certainly does not mean the end of the growing season. Cooler temperatures and naturally moist soil create excellent conditions for sowing fast-growing vegetables, winter salads, herbs, hardy flowers and green manure crops.
If you are wondering what to sow in September in Ireland, explore our carefully selected collection of vegetable, herb and flower seeds suitable for autumn sowing. With the right varieties and a little protection from colder weather, you can continue harvesting fresh produce through autumn and winter while preparing your garden for next spring.
Vegetables to Plant in September
There are still plenty of vegetables to plant in September, particularly quick-growing leafy crops and cold-tolerant varieties.
Suitable September sowings may include winter lettuce, spinach, rocket, radishes, corn salad, oriental salad leaves, mustard greens, winter purslane and selected spring onions. These crops can make productive use of spaces left behind after summer vegetables have been harvested.
Some varieties can be sown directly outdoors early in the month. As temperatures fall, sowing in a greenhouse, polytunnel, cold frame or beneath a cloche can improve germination and help protect young plants.
Whether you grow in a vegetable patch, raised bed, greenhouse or containers, September offers several opportunities to produce fresh leaves and vegetables during the cooler months.
Flowers to Plant in September
September is also a useful month for sowing selected hardy flower seeds. Autumn sowing allows young plants to establish roots while the soil is still warm, often producing stronger plants and earlier flowers the following year.
Selected hardy annuals, including certain cornflowers and calendula, can be sown directly into prepared soil during September. Some perennial flower seeds may also benefit from autumn sowing and exposure to naturally cooler winter conditions.
Always check the instructions for the individual variety, as not every flower is suitable for autumn sowing. In colder or exposed gardens, seedlings may benefit from protection during severe frost or prolonged wet weather.
What Seeds Can I Sow in September?
The best seeds to sow in September depend on the variety, local weather and whether you are growing outdoors or under protection.
Popular choices can include:
- Winter lettuce and mixed salad leaves
- Spinach and perpetual spinach
- Rocket and mustard greens
- Mizuna and other oriental leaves
- Corn salad
- Winter purslane
- Radishes
- Selected spring onions
- Coriander, parsley and chervil
- Hardy annual flower seeds
- Selected perennial flower seeds
- Green manure and cover crop seeds
Sowing several small batches rather than everything at once can help provide a steadier harvest and reduce the risk of losing an entire crop to difficult weather.
Seeds to Sow Under Cover in September
A greenhouse, polytunnel, cold frame or bright indoor growing space can greatly expand your September sowing options.
Leafy vegetables and herbs grown under protection are less exposed to heavy rain, strong winds and early frost. Winter salads, spinach, rocket and oriental leaves are particularly useful for protected autumn growing.
Microgreens can also be sown indoors throughout September for a quick supply of fresh, nutritious shoots. They require very little space and can be grown on a bright windowsill, making them ideal for homes without a large garden.
Sow Green Manure in September
September is an excellent time to sow suitable green manure and cover crop seeds on empty vegetable beds. These crops help cover bare ground, suppress weeds and protect soil from heavy winter rain.
Depending on the variety, green manure can also add valuable organic matter when cut down and incorporated into the soil. Always choose a variety suited to autumn sowing and consider your planned crop rotation before planting.
Instead of leaving harvested beds empty over winter, sowing a cover crop can help keep your soil protected and productive.
Growing from Seed in September
For successful September sowing, begin with weed-free, well-prepared soil or fresh seed compost. Keep newly sown seeds evenly moist, but avoid waterlogged conditions as autumn rainfall increases.
Shorter days and falling temperatures mean seeds may germinate more slowly than they would in summer. Sow early in the month where possible and use fleece, cloches or an unheated greenhouse when additional protection is needed.
Always follow the sowing guidance on the individual seed packet. Different varieties of the same vegetable, herb or flower can have very different sowing periods and growing requirements.
Shop Seeds to Plant in September
Not sure what to plant in September? Browse our hand-picked collection of seeds to plant in September in Ireland, including vegetables, herbs, salad crops, flowers and green manure varieties selected for autumn sowing.
From productive winter salads to flowers for next year, September still offers plenty of opportunities to grow something new.
Browse our September seed collection and grow something beautiful with purpose.
