What to Sow in September: Vegetables & Flowers to Grow Now 🌱

September is a month of change in the garden. The days are beginning to shorten, mornings feel cooler, but the soil is often still holding onto the warmth of summer.

And that makes it a wonderful time to sow.

While some September sowings will give us fresh leaves through autumn and winter, others are all about looking ahead. Hardy flowers sown now can establish their roots before winter, while overwintering vegetables can quietly settle in ready to grow away when conditions improve.

It’s a lovely reminder that gardening doesn’t have to stop as summer ends — we simply start growing with the next season in mind.

Hardy Annual Flowers

For hardy annual flowers, September can be one of the most rewarding sowing times of the year.

Rather than waiting until spring, sowing now gives young plants an opportunity to establish before winter. While there may not be much happening above the soil during the colder months, those young plants are already building the foundations for next year.

Once spring arrives, they are ready to get growing.

Autumn-sown hardy annuals will often flower earlier than those sown in spring and can develop strong, well-established root systems that help them cope when conditions become warmer and drier.

It’s a wonderfully natural approach to growing — working with the seasons and allowing plants the time they need to establish.

Try Cornflowers and Larkspur Giant Imperial Mix, along with hardy annuals such as ammi majus, nigella, calendula, orlaya and Iceland poppies.

As well as bringing beautiful colour to the garden next year, choosing a mixture of flowers can help create a more diverse growing space, providing nectar and pollen for bees and other beneficial insects.

Sweet peas can also be autumn sown. They tend to do best when started in deep pots, modules or root trainers, giving their roots plenty of room to develop.

One important thing to remember is that not every annual flower is suitable for autumn sowing.

Tender and half-hardy annuals such as cosmos and zinnias won’t tolerate frost, so keep those seed packets somewhere safe and wait until spring.

Sow direct in to the soil or in to trays and pots

Both methods can work — and your garden and soil can help you decide which is best.

Sowing directly into the soil means plants establish their roots exactly where they are going to grow. This can produce strong plants with good root systems and avoids disturbing young roots through transplanting.

Choose an area with well-drained, healthy soil, clear away competing weeds and prepare the surface gently before sowing.

If your garden has heavy soil that tends to stay wet over winter, however, direct-sown seedlings can struggle.

In these conditions, sowing into modules gives you more control. Young plants can be kept in a cold frame or unheated greenhouse, where they are protected from the worst of the winter weather before being planted out.

Modules can also make it easier to protect those precious young seedlings from hungry slugs and snails.

There isn’t one method that suits every garden. Look at your soil, your local conditions and the plants you’re growing, and let nature help you decide.

Vegetables

The vegetable patch still has plenty of potential in September.

Leafy crops are particularly useful at this time of year. Perpetual Spinach can be sown in August or September and overwintered for fresh new growth from late winter.

You can also sow winter lettuce, oriental greens, chard and spring cabbage, depending on the variety and your local conditions.

White Lisbon Spring Onions are another good choice. An autumn sowing can establish before winter and give you an earlier crop next year.

And don’t overlook some of the smaller leafy crops and herbs. Wild Rocket and Chervil can be useful September sowings, giving you another opportunity to grow fresh food as we move away from the main summer season.

Towards the end of September, gardeners in milder parts of the UK can also begin sowing suitable varieties of broad beans for an earlier crop next year.

The important thing is to choose varieties specifically suited to autumn and overwintering, rather than assuming every variety of a vegetable will cope with colder conditions.

Natural Grower Tip 🌱

September sowing is all about looking ahead.

Sow leafy vegetables now to help extend your home-grown harvest, choose overwintering crops that will be ready to grow away when spring returns, and sow hardy flowers that can spend the colder months quietly establishing their roots.

Most importantly, keep looking after the soil beneath them.

Autumn is not the end of the growing year. In many ways, it’s the beginning of the next one.

Healthy soil. Healthy plants. Naturally.