Choosing the best vegetables to plant in September is all about recognising the shifting of the seasons – and embracing the benefits of those changes. Yes, spring is great for potential, and summer is lovely for reaping the rewards in big volumes. But in autumn, you get a magical blend of possibilities: fast-growing crops that hit their stride in the cooler temperatures; miniature (or baby) crops of slow-growing roots; and overwintering staples that bulk up steadily during the next few months in readiness for the next gardening season.
Around the autumn equinox, you lose a bit of light as well as warmth. But pick the right crops and you can turn this to your advantage in your vegetable garden. Sow greens, oriental leaves, spring cabbage and Japanese onions now, and they will flourish in the combination of cooler temperatures and relatively warm ground levels. Quick-maturing crops like radishes that might have taken four weeks from seed to harvest in summer might take a few weeks longer – but it’s worth it. And slow-developing brassicas like spring cabbage relish every week of growth now to bulk up to their full potential and flavour.
With containers, cold frames and cloches at the ready, you can start off a stack of goodies now for healthy feasts far into the colder months.
1. Collard greens
Beloved of the ancient Greeks, these hearty leafy beasts taste better after a bit of exposure to frosts on the plot, so they are ideal for planting in September. Verdant, robust and reminiscent of cabbage, collards (Brassica oleracea) are packed with vitamins K, A and C, calcium and B6, and they help to lower cholesterol. Start now and make successive sowings to maximise cropping potential into the depths of winter.
These greens can be planted in the ground and in raised beds as well as containers, but bear in mind that they need a fair bit of room for bulking up. Plant in full sun or partial shade in moist, rich, well-draining soil with a slightly acidic pH (6.5). Space 45-60cm apart, or thin accordingly. An 8cm mulch will keep the ground moist and prevent weeds.
As long as these leafy greens receive a regular supply of moisture, they are ready for harvesting 65-75 days after sowing/planting. If they have been touched by frost, young leaves taste sweeter and work well steamed or braised. Try glossy ‘Green Glaze’, prolific ‘Flash’, and tender ‘Champion’.
2. Japanese onions
If you haven’t grown Japanese onions before, you’re in for a treat. These hardy overwintering varieties, also known simply as autumn planting onions, can grow outside over the cooler months and deliver crunchy goodness come spring. What makes them so perfect for planting in September is that they need less light than other onions, so the shorter days won’t faze them.
They are also excellent options for starting in September thanks to their tolerance of the cooler climes. As Chris Bonnett of GardeningExpress.co.uk points out: "Onions are tough enough to withstand the cold weather throughout the winter. Just keep an eye on them, and if the conditions get too frosty, you can always cover them with a fleece to be on the safe side."
If you’re stuck on what variety to choose, ‘Senshyu Yellow’ is a reliable, heavy yielding globe variety that can survive temperatures down to -18°C. ‘Toughball’ (available from Amazon) has good tolerance to botrytis and downy mildew, which you need for an overwintering type. Then there’s the shiny red-skinned ‘Electric’, (available from Crocus) which keeps for up to four weeks from harvest. Plus, there's ‘Troy’ and ‘Radar’, (also from Crocus) which have excellent bolt resistance.
Specially bred for sowing from late August to early September to mature in the following July. Produces a semi-globe shaped crop with a straw-like colour.
3. Baby turnips
Turnips are one of the fastest-growing vegetables to plant in September. These crunchy wonders do best in cool, moist conditions. "If planted now, they take around six weeks until they’re ready to harvest. Perfect – and just in time for winter," says Chris Bonnett.
Sow seeds thinly in shallow drills, 1cm deep, with rows 30cm apart. Thin out seedlings until 20cm apart for baby roots. Water regularly, or roots won’t taste as nice or grow sufficiently. Dry conditions can cause plants to bolt, which stops roots growing. Then just make sure you follow our tips on how to get rid of weeds to ensure they don't appear and encroach on your growing turnips.
Just keep the soil lightly moist, and your baby roots will be healthy and yummy. Try 'Tokyo Cross', 'White Lady', 'Purple Top Milan' (available from Dobies) and 'Hakurei'.
These can be sown between April and September and harvested between July and December. For the best flavour, harvest when they are ping pong ball size.
4. Arugula (rocket)
Arugula (or rocket) is highly adaptable to a cool season of cultivation. Easily sown from seed, this leafy annual cranks up the heat with tasty crops that can be harvested four weeks after sowing. Its fast maturity makes it amongst the best vegetables for September planting – and successive sowing ensures harvests far into winter.
As gardening expert Lucy Chamberlain explains, the still-warm days of autumn are perfect for rapid germination. "Just sow straight into the greenhouse border, or into modules in a propagator to transplant to the border, trays or growing bags in October," says Lucy.
It prefers full sun or partial shade with well-drained soil (pH 6-7). Once you have thinned seedlings to 10-15cm apart, these plants just need regular watering due to their shallow root systems.
Depending on the varieties, you can harvest as quickly as 40 days after sowing (four-seven weeks): young, tender leaves are best. Just leave two thirds of each plant intact for multiple harvests. Try red-veined 'Dragon's Fire', heirloom ‘Slow Bolt’ and 'Scorpion' (available from Dobies) for something with a bit of extra kick.
Can be sown throughout the year and will do best in sun or semi shade. Has distinctive red veins and a strong peppery flavour.
5. Wok broc
Wok broc (aka Chinese broccoli) is a great vegetable to plant in September. This exotic-sounding crop, also known as kai lan, is a bit like conventional sprouting broccoli. It’s fast-growing, hard-working and packed with antioxidants and vitamin C.
Sow directly into moist, weed-free soil in an open, sunny site. Drop the seeds into a 2.5cm deep trench, or scatter across the surface of large pots. Thin to 30cm apart when seedlings are large enough to handle. Water well and make sure the growing area remains weed-free.
Because this crop is fast-growing, you can harvest stems and leaves six to eight weeks after sowing. Remove a few centimetres of the stems when the flowers appear. We recommend you leave a few flowers on the plant, though – they are great for pollinators in an eco-friendly garden.
6. Mustard leaves
Mustard leaves are some of the most impactful vegetables to plant in September as they bulk up quickly from seed, make the most of space in a small garden or veg patch and thrive in damp conditions. And if you sow every three weeks, they will supply you with tender pickings all winter.
"Simply sow directly into moist soil (pH 6-7). As temperatures fall, cover with a cloche, which prevents foliage turning leathery in colder weather," says Lucy. Alternatively, grow in large shallow garden planters.
As seedlings develop, thin to 8cm apart, and water well. As long as you plant in a nutrient-rich soil, you shouldn’t need to add any liquid feed. Just keep an eye on weeds and maintain cool temperatures; exposure to a little frost is tolerated and can soften and sweeten flavours.
Harvest mustard (Brassica juncea) 45-55 days after sowing. Either cut whole or pick outer leaves as baby greens to encourage further growth in a cut-and-come-again style. Mustard plants can also be grown for their peppery seeds if you leave one to flower.
Distinctive breeds include crinkly ‘Red Giant’ (available from Dobies) and pretty ‘Osaka Purple’.
This variety is very winter hardy and slow to bolt. Harvest when the leaves are red and use in a wide range of salads or dishes.
7. Spinach
If you want to grow spinach in September, choose a hardy cultivar and select a sunny spot, and you can reap the rewards well into winter. As Chris Bonnett points out, "If you harvest regularly, it may even last until early spring."
Direct-sow in a drill 2.5cm deep, water and cover lightly with soil. Thin to 10-15cm apart, then just keep well watered. You can also sow in large containers.
Six to 10 weeks later, harvest every alternate plant. Cut back to just above the base to encourage more leaves. Winter cultivars may need protection from October; cover with cloches and cold frames and protect with straw.
Grow autumn-sown varieties which have thicker leaves and are less inclined to bolt. Our favourite is ‘Mikado’, an F1 spinach (available from Thompson & Morgan). It produces excellent yields from multiple side-shoots. ‘Violin’ and ‘Amazon’ (available from Amazon) have strong resistance to bolting, while ‘Apollo’ (available from Thompson & Morgan) and ‘Palco’ (from Dobies) are resistant to downy mildew.
8. Coriander
Coriander can be started from seeds in pots. Alternatively, sow direct and protect seedlings under cloches in well-drained soil.
Sow thinly in the ground or multi-celled trays or pots and cover lightly. Germination takes 7 to 20 days. Keep sowing every two weeks for a constant supply. Make direct sowings 1cm deep in rows 30cm apart. Keep moist, but don’t overwater and weed regularly. Coriander can be harvested at 10 to 15cm tall and used on a cut-and-come-again basis.
For an easygoing, fast-growing coriander, try British-bred ‘Calypso’, (available from Thompson & Morgan), finely cut ‘Confetti’ (from Suttons) or vigorous ‘Leafy Leisure’. Or opt for a bolt-resistant variety such as ‘Slowbolt’ (from Dobies).
9. Pak choi
Plump, nutritious and fast-growing, pak choi is one of the essential vegetables to plant in September. It is well suited to shorter autumn days and its fat leaves make the most of what natural light is available. "You may not get massive rosettes, but a short, 3ft row will provide ample yield," says Lucy Chamberlain. "Sow directly outside into moist soil. As temperatures fade later in the month, cover the rows with a cloche, which will also prevent the foliage turning leathery," she adds.
The trick when you grow pak choi is to avoid root disturbance and sow in situ. Plant four seeds at 30cm spacing, then thin to the strongest seedling. Keep well watered to avoid bolting.
Great varieties include glossy 'Tatsoi Supi', crisp 'Joy Choi' and pretty 'Pak Choi Red'.
Plant a mix of varieties with this selection of seeds, which contains 50% F1 Rubi and 50% Hanakan. The red variety gets more intense in cooler weather.
10. Pea shoots
Delicate and tender yet bursting with flavour and nutrients, pea shoots are a top crop to start now and shoots are ready in weeks. Content in a cold frame or greenhouse, they are quick to grow.
Grow outdoors in fertile, well-drained soil, sowing seeds an 2-3cm apart. It’s also possible to cultivate pea shoots in containers in a greenhouse or tunnel. If you use containers, make them big; grow bags and larger trays are ideal. Place in a well-lit spot but avoid direct sunlight, and keep moist. Harvest with scissors an inch above compost level when plants are 15cm tall. Cut in clumps, allowing a reasonable amount of the plant to regrow.
Top varieties include compact ‘Meteor’ and prolific ‘Feltham First’. We also recommend ‘Twinkle’ for downy mildew tolerance. And for a crunchy nutrient boost, ‘Anubis’ (available from Dobies) produces shoots in three weeks, and you can enjoy a second picking a few weeks later.
11. Radishes
September is your last chance this year for growing radishes, so take advantage of this final push for crunchy croppers through autumn.
Direct sow in the ground or sow in containers. If sowing in the ground, make short drills 15cm apart and sow 1cm deep. Sow summer radish seeds 2.5cm apart, and winter varieties 15cm apart. And keep the soil moist. As radishes are fast growers, try interplanting some between slower-growing veg like potatoes. You can harvest four weeks from sowing: these veggies are best eaten young.
Great varieties to try include sweet ‘Watermelon’ with its bright magenta flesh and peppery ‘China Rose’ (available from Dobies), which is cold-tolerant and can be left in the ground over winter. Not forgetting bold purple ‘Felicia’ (from Thompson & Morgan) with its slender roots, and ‘Rainbow Mix’, a colourful crunchy blend (from Suttons).
With its white skin and bright pink inside, this radish variety is perfect for salads and garnishes. Has a relatively mild flavour.
12. Spring cabbage
Tasty, tender, nourishing and bulging with goodies like vitamin C, spring cabbage is a reliable staple for the kitchen garden – and September is the key time to start off crops for next year. Time to overwinter is crucial in order to produce those bulky heads.
Pick an open, sunny or semi-shaded spot with an alkaline soil type. Start some off both in modular trays and direct in the ground using a seed bed, to hedge your bets. Once planted out, give plants a soak every eight to 10 days. As you see heads expand, water generously to improve bulk. You can pull up some crops as greens when the leaves are tender. Four to six months later, the main heads should be ready to harvest. Cut through the stem with a sharp knife just above ground level. For a bonus crop, cut a cross in the stump. You’ll get several small cabbages a few weeks later.
Great varieties include tender sweetheart ‘Wheelers Imperial’ (available from Suttons). Then there’s ‘Duncan’, with its dark upright leaves. ‘April’ (from Thompson & Morgan) is an early spring variety with compact heads.
Another good September gardening job is to order new fruit bushes for planting in November to March. Organic expert Bob Flowerdew recommends buying a blackcurrant bush.
To boost your returns, take a few cuttings from the main bush and root them in situ. Other options include red/white currants and gooseberries. Blackcurrants are also a good choice if you're interested in growing fruit in pots and containers.
For one final task – don't forget about the key plants to prune in September before it's too late.
The original version of this article previously appeared on Gardeningetc, a sister website to Homebuilding & Renovating.
