What to sow in September

Plants flowering in September are a real ornament to the garden, allowing you to keep the summer atmosphere for a little longer. Colourful flowers and lush shrubs enliven the space, encouraging you to spend time outdoors even as autumn approaches.

Early Autumn is the best time to plant or sow seeds, as crops thrive when started in September. Read our tips on what to grow and how to plant.

Seeds to sow in September

Flowers to sow/ plant in September

1. Seeds to sow in September

Broad beans

Common name: Broad beans
When to sow: late September
Position: Full sun
Cultivation notes: Sow seeds deep and well apart in fertile soil. Allow water to drain well.

Easy to grow outdoors from seed in raised beds and large pots. Broad beans are very tasty in soups, stews and salads. We recommend a variety called Aguadulce Claudia, which establishes over winter, ready for cropping the following spring.

Fork in plenty of compost or manure and rake the surface to a fine, crumbly texture.
Mark out deep drills, 20cm apart, and sow the seeds 5cm deep.
Cover with soil, firm down and water in well. Seedlings should appear in a few weeks. Protect from birds and squirrels by placing netting over the sown area.
As soon as the flowers appear, pinch out growing tips to prevent blackfly attacks.
Stake taller broad bean varieties and wrap rows of string around the supports.
For the most tender beans, harvest the pods at 6cm long.

Radish

Common name: Radish
When to sow: early September
Position: Full sun
Cultivation notes: Sow seeds about 2cm deep in between slower growing crops and water regularly.

It only takes three to six weeks for this crisp, crunchy vegetable to be ready for pepping up your autumn salads. The young leaves make a particularly delicious microgreen.

Sow seeds at weekly intervals directly into finely raked soil. Put protection in place to keep slugs and snails away.
Water regularly and thin out seedlings by 2.5cm to help roots form.
Grow radishes in between rows of other, slower growing crops – your row of radishes will help to suppress unwanted weeds.

Garlic

Common name: Garlic
When to sow: late September
Position: Full sun
Cultivation notes: Plant cloves, pointy end up, in fertile soil. Water as required, but stop a couple of weeks before harvest.

If the conditions are right, you can plant garlic from September, even in Northern Europe.The cloves also benefit from a period of cold, which helps the roots and shoots develop properly.

The hardneck variety is best for cooler climates. It has fewer cloves per bulb compared to the softneck type seen in supermarkets, but are generally hardier.
Choose a warm, sunny spot and use a dibber to make holes, 15cm apart, in well-prepared, fertile soil.
Plant the fat end of each clove downwards, the pointy end 2.5cm below the soil surface.
Lay over bird netting or horticultural fleece until the shoots are 5cm tall.
Harvest from July onwards, once the top growth starts to die back.

Salad

Common name: Salad
When to sow: throughout September
Position: Full sun
Cultivation notes: Sow seeds about 1cm deep in beds or pots and water well.

You can sow salad crops right through to mid-September – directly into the soil while it’s still warm. Some of our winter favourites are mustard leaf, mizuna, lamb’s lettuce, wild rocket, and the more unusual purslane.

Sow seed outside in a sheltered spot outdoors or in pots.
Plant out seedlings in rows 20cm apart, spaced at 10cm intervals, and water well.
For best results, cover plants with a sturdy cloche to help them reach perfect picking size before the cold sets in.
You can also sow winter salad seeds in pots or window boxes. Do this every week for a continuous supply of fresh leaves, just outside your kitchen door.

Top tip: Choose a sheltered, sunny spot for growing vegetables to protect them from cold winds. And keep the soil free-draining so that plants aren’t left sitting in icy water.

2. Flowers to sow/ plant in September

Annual plants

Marigold (Tagetes erecta, Latin) - an ornamental plant with intense orange or yellow flowers that bloom from summer to late autumn. The velvet plant is easy to grow and grows well in full sun,
China aster (Latin: Callistephus chinensis) - has colourful flowers in shades of purple, pink, white and red. China asters flower until late autumn,
Calendula (Latin: Calendula officinalis) - distinguished by its orange or yellow flowers. It also has medicinal properties. It flowers from early summer to late autumn,
China pink (Latin: Dianthus chinensis) - flowers with intense, bright colours such as red, pink and white. China pinks flower in summer and early autumn, decorating flowerbeds and balconies.

Biennial plants

Ornamental mullein (Latin: Verbascum x hybridum) - grows to a height of 1-2 m and produces large, yellow or purple flowers. It blooms in the second half of summer and early autumn,
Hollyhock (Latin: Althaea rosea) - a tall plant with large, pink flowers. It flowers in the second year after planting and is a popular feature of country gardens, reaching heights of up to 2 m.

Perennials and bulbous plants

Showy stonecrop (Latin: Sedum spectabile) - is a low perennial that produces large, pink or red flowers in September. It is drought-tolerant and makes an excellent addition to rock gardens,
Black-eyed Susan (Latin Rudbeckia fulgida) - a plant with intense yellow flowers that bloom from summer to autumn,
Japanese anemone (Latin: Anemone japonica) - a perennial that blooms in late summer and autumn, with flowers in shades of white, pink or red. It is an ideal plant for shady gardens,
Dahlia (Latin: Dahlia) - a bulbous plant that flowers from summer until the first frost. Dahlias come in a variety of shapes and colours. Dahlia bulbs should be dug up after frost and stored over winter,
Autumn crocus (Latin: Colchicum autumnale) - blooms in autumn, usually in shades of purple. The flowers appear just before the leaves fall.
Chrysanthemum (Latin: Dendranthema × hortorum) - flowers from August to November. Its rich colour palette - from white and pink to intense reds and yellows - brings an atmospheric mood to the garden. It grows best in sunny locations in slightly acidic soils and tolerates colder weather perfectly.

Shrubs to sow in September

One of the more popular shrubs flowering in September is the Summer Lilac (Latin: Buddleja davidii). Also known as the 'butterfly bush', the buddleia is distinguished by its long, fragrant inflorescences in shades of purple, pink and white.
The common heather (Latin: Calluna vulgaris) also flowers at the same time. Heather brings colourful accents to the garden, especially in the form of purple, pink or white flowers. These plants prefer sunny positions and acidic soils.

In September you can also admire:

Panicle hydrangea (Latin Hydrangea paniculata) - blooms from summer to early autumn. It has white or slightly pink flowers,
Hortensia (Hydrangea macrophylla, Latin) - although it mainly blooms in summer, in September its white, blue, red or pink flowers continue to decorate gardens until the first frosts. It is able to change colour under the influence of soil pH,
Blue spirea (Latin: Caryopteris × clandonensis) - a blue flowering shrub in September that attracts bees and butterflies. It puts out beautiful blue flowers from August to September, making it an excellent choice for flowerbed