September is often overlooked as a month for taking a breather rather than planting, with many gardeners thinking the growing season is winding down and focusing primarily on tidying up summer’s glorious chaos by cutting back. Knowing what to plant during September is where the experienced gardeners beat newbies! September is the prime time for planting bulbs and other plants ready for next year. Whilst others are already dreaming of next year’s garden catalogues, I’m out here at Garden Ninja HQ maximising September’s unique conditions because I know this autumnal month offers great growing opportunities.
The combination of still-warm soil, increasing rainfall, and cooler air temperatures creates the perfect storm for establishment that smart gardeners capitalise upon. Plants get the best of both worlds with warm roots for growth and cool tops to prevent stress. So grab your trowel and join me as I show you exactly what you should be growing this September, whether for late autumn harvests or spectacular spring displays!
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Most gardeners in September are starting to mentally switch off after the summer rush of July and August. Most gardeners are looking to let their garden ‘go to rest’ for the winter, which is a real shame, as you miss out on another couple of months of gardening if you follow that old rule! I’m here to tell you, Ninjas, that this is actually prime time for getting ahead of the game.
Late summer presents unique opportunities that many gardeners completely miss:
Top of your ‘what to plant in September’ list should be spring bulbs, as they start being available this month in garden centres and online at nearly all gardening retailers, and it’s good to buy them early before the best ones and unique cultivars sell out. I find that plants like daffodils are super good value when bought in bulk online. These are absolutely the easiest way to guarantee stunning spring colour with minimal effort.
The key with spring bulbs is to plant them deeply, at least 2-3 times the depth of the bulb itself, as my guide below illustrates.
Tulips, daffodils and all other spring-flowering bulbs can be planted in September and all the way through to November. Allowing you to bulk up your spring borders and flower beds. What’s not to love about bright, cheerful flowers emerging just after the death of winter? Spring bulbs also provide much-needed pollen and early nectar for honeybees and other wildlife. Plant a mixture of early, mid, and late varieties for continuous displays from February through May.
Early Season Champions like Crocus, Hyacinths, Snowdrops and Scillas, along with the first Narcissi that put down their roots in autumn. Before Daffodils and then tulips show themselves. These bulbs are great value, and by planting a mix of different bulbs, you can achieve succession planting in spring, where one bulb is just finishing, such as snowdrops, before a daffodil emerges. Clever eh!
Woodland Specialists also benefit from September planting. September planting is also good for woodland bulbs such as Erythroniums and Trilliums, along with the charming Fritillaria meleagris, all of which dislike being out of the soil where they tend to dry out. I absolutely love planting Winter Aconites from small corms; they can be a bit temperamental, but they are a good test of your patience and gardening skill for shady woodland gardens.
September is absolutely prime time for sowing hardy annuals that will deliver show-stopping colour weeks before their spring-sown cousins even think about germinating. These reliable performers are the backbone of cottage gardens and front gardens, providing maximum impact for minimal investment whilst filling those crucial gaps between spring bulbs and summer perennials. By planting them in September, you can get them to germinate before winter, and as long as we don’t have crazy cold winters, they are then ready to go next spring!
These hardy beauties can be sown directly outside now and will survive winter to bring summer colour to borders and containers, though I always recommend labelling your sowings so you don’t accidentally weed them out come spring! Alternatively, sow in containers in a cold frame or greenhouse if you prefer more control and if you think you’re going to have heavy winter frosts.
Cerinthe major ‘Purpurascens’ (Honeywort) is absolutely one of the most uniquely beautiful flowers you can grow from September sowings. This gorgeous hardy annual has silvery blue-green leaves and pretty bell-shaped purple flowers, which are a magnet for bees. A single stem in full bloom can be silver, blue, purple, and green all at the same time. The gracefully arching stems with nodding purple blooms surrounded by sea-blue bracts create an absolutely mesmerising display. It makes a wonderful cut flower and self-seeds readily once established.
Larkspur ‘Misty Lavender’ (Consolida ajacis) produces the most exquisite smoky, dark lavender-grey spires that will give your floral arrangements real sophistication. These annual delphiniums can be tricky to grow from seed. They don’t need heat to germinate, and indeed can benefit from a week or so of cold in the fridge before sowing. A sultry, smoky new form of this invaluable and reliable cut flower. It mixes well with any colour and creates towering architectural elements perfect for cottage garden styling. Larkspur needs both cold stratification to break seed dormancy and trigger germination and vernalisation (a period of cool growing temperatures) to trigger flower development.
Sweet Peas (Lathyrus odoratus) absolutely deserve star billing in any September sowing programme. Seeds can be sown all the way through to the end of October, directly in the garden or in containers. These climbing beauties, when sown now, develop extensive root systems over winter and burst into fragrant flower from early spring. Planting them in empty toilet or loo rolls allows them to develop mega deep roots. ‘Cupani’ offers heritage charm with incredible scent, whilst ‘Winston Churchill’ produces robust stems perfect for cutting gardens.
Orlaya grandiflora (White Lace Flower) is an absolute must-have for anyone seeking elegant white flowers with incredible staying power. It bears lovely fern-like foliage and clusters of pure white flowers, similar to lace-cap hydrangeas but far smaller and better for small garden designs. Flowers appear over a long period, often until the first frosts. This charming and graceful plant blooms over an exceptionally long flowering period, from early summer until the first frost. Sow seed in autumn for early-flowering large plants – autumn-sown specimens develop into much more substantial plants than spring sowings and provide earlier, more abundant flowers perfect for cutting gardens.
Ammi majus (Bishop’s Weed) produces superior results from autumn sowings. Ammi majus is best sown in autumn, resulting in bigger, better flowers in early summer. These delicate white lace-cap flowers are absolutely essential for cottage garden schemes and cutting gardens, creating that perfect foil for bolder colours. This super floaty plant is airy and is often used in wedding bouquets due to its delicate white lacey flowers. This plant will bring the middle of the flower bed height, making your planting schemes seem much more detailed.
For those with protected growing space, September opens up additional possibilities for tender varieties that need protection from harsh winter conditions by growing on seeds and plants in your greenhouse. Here are two plants that require winter protection rather than being sown directly outside.
Baby’s Breath (Gypsophila) can be started in containers now for transplanting in spring. The delicate clouds of tiny white flowers are indispensable for flower arrangements and romantic garden schemes.
Honesty (Lunaria annua) establishes beautifully from September sowings in containers. The spring flowers are lovely, with the bright purple flowers, but those spectacular silvery seed pods are the real prize, which are perfect for dried arrangements and winter interest.
This is one of my favourite all-time annual plants due to its autumnal interest; in September, the seed pods become translucent, reminding me of earrings. Gorgeous plant just for the dried seed heads alone in the garden! Just look below at how bewitching the seed heads are!
September offers the perfect window for establishing from seed, splitting or dividing herbaceous perennials that will form the structural foundation of next year’s displays. These long-term investments, which typically last for decades, reward autumn planting with stronger root systems and earlier flowering. I always advocate planting the majority of your garden with herbaceous perennials as they are packed full of pollen and nectar for wildlife and cut down on your carbon footprint compared to annuals, which need growing every year with fresh compost, water, etc.
Now’s the time to divide established clumps that have become congested, creating multiple plants for free whilst rejuvenating flowering performance. If you haven’t already seen my guide on how to divide plants, you can read that here, and it’s super easy even as a beginner gardener. Dividing involves lifting and then splitting the rootstock of your herbaceous perennials before the winter dormancy.
Hostas are absolutely brilliant for September division and practically foolproof for beginners. These shade-loving beauties can be lifted and pulled apart gently, with small fibrous-rooted plants easily divided by hand. Hostas are almost indestructible and can last several days to even a week in a pile in the shade until you decide where to replant, as long as you don’t let them dry out. Use a sharp spade to slice the clump into sections and plant the hosta pieces at the same depth they were originally. Perfect for creating dramatic foliage displays in shady spots!
Rudbeckia (Black-eyed Susan) responds incredibly well to September division and rewards you with masses of cheerful golden blooms. You can divide black-eyed Susan either in autumn or spring when the plant is entering or exiting dormancy, and they should be divided every three or four years. As the temperatures cool in September, once they have finished flowering, the plants can be dug up and divided. Black-eyed Susans are easy to propagate through root division, and it took me about fifteen minutes to turn one plant into about seven! These native beauties are pollinator magnets and practically indestructible!
Echinacea (Purple Coneflower) creates spectacular displays when divided in September, and it’s easier than most people think. Some plants, like echinacea, are not as easy as others, but use a sharp spade or even a bread knife to separate the plant into smaller pieces. You can divide Echinacea purpurea every 3 to 5 years, and the best time is in early spring or late fall when the plant is either dormant or nearly dormant. Once you have manageable pieces, examine them to identify those with undamaged stems and healthy roots. You can easily divide at least five individual plants from the original. These drought-tolerant natives are absolute wildlife magnets!
September is an ideal time for sowing herbaceous perennial seeds that require cold stratification or prefer autumn establishment, especially those that have a very long germination window (Scabious, I’m looking at you, girl). Some herbaceous perennials can take up to 8 weeks to germinate, meaning that under glass over the autumn time can help you speed up this process so that by next spring, they are already plug plant-sized plants!
Delphiniums are absolutely magnificent when sown fresh in September for spectacular displays next summer. You can save delphinium seed to sow from February to June, or September to October, and September timing allows the seeds to benefit from natural cold stratification over winter. Nothing quite beats the drama of delphinium flowers – in June and July, they produce towering flower spikes that can reach over 2m tall. They’re probably best known for their vivid sapphire blue flowers, but they also come in mauve, pink, white and even red. The ‘Pacific Hybrids’ were developed in the 1950s and are short-lived perennials perfect for cottage garden styling, whilst ‘Magic Fountain’ series offers compact varieties ideal for smaller spaces.
Hollyhocks (Alcea rosea) are absolutely essential for any self-respecting cottage garden and sow easily in September for the year after. Sow hollyhock seed under cover in September which is when the plant is naturally setting and dropping seed. No cottage garden would be complete without a bright, blowsy hollyhock or two, and they self-seed very freely once established. Sometimes biennial, they can also be perennial, often described as short-lived perennials lasting three or four years. ‘Black Knight’ offers glossy, almost black flowers that stand out beautifully, whilst the ‘Halo’ seed mixtures provide single flowers in pastel colours with central darker eyes.
Wallflowers (Erysimum) develop robust root systems from September sowings and create the most delightful spring fragrance. Sow wallflower seeds during late summer months in trays of suitable seed starting mix and place in a cool, sheltered location. These spring-flowering bedding plants provide a wealth of colour and many produce delightfully scented flowers perfect for cutting gardens. The perennial ‘Bowles Mauve’ flowers from February right through to midsummer and well deserves its RHS Award of Garden Merit, whilst bedding varieties like ‘Fire King’ offer brilliant orange-red blooms that absolutely glow in spring borders.
September vegetable sowing focuses on crops that absolutely thrive in cooler conditions, providing fresh harvests when shop prices are at their highest and quality at its lowest. It always seems to surprise new Garden Ninjas that you can still grow a number of vegetables throughout autumn and even into winter. You just need to know which vegetables can grow in cooler or even cold climates. Strategic succession planting ensures continuous harvests well into winter.
The brassica family absolutely dominates September sowing for excellent reasons – these cool-season crops establish beautifully in late summer conditions and provide essential fresh greens throughout winter.
Winter Cabbage varieties sown now mature perfectly for Christmas harvests. ‘January King’ develops stunning purple-tinged leaves that are not only delicious but provide ornamental value in winter vegetable plots.
Kale varieties sown now develop into substantial plants that harvest continuously throughout winter. Kale is a wonderful vegetable to plant in August and can be sown directly into the ground. Just be sure to shelter your kale from strong winds, particularly when the weather starts to change in September/October, as it does have a tendency to blow over! ‘Nero di Toscana’ (Cavolo Nero) provides architectural structure whilst ‘Redbor’ adds burgundy foliage to ornamental vegetable gardens. Great foer smoothies and super food lovers!
Radishes excel in the cooler conditions of September. There is still time to get a radish crop this year, as they will grow within a few weeks of being planted. The moderate temperatures prevent the peppery heat development common in summer sowings. ‘Cherry Belle’ and ‘French Breakfast’ varieties mature rapidly and can be succession sown every two weeks.
Spinach varieties germinate reliably in September soil temperatures. Sow hardy spinach varieties, such as ‘Giant Winter’ direct in shallow drills in well-prepared soil, or in pots. The spinach will enter dormancy as temperatures drop, but will regrow as soon as they increase again in spring. ‘Medania’ and ‘Space’ provide tender leaves throughout autumn and into spring.
Rocket (Arugula) thrives in September conditions, preferring cooler weather to prevent bolting. Wild rocket varieties self-seed freely, creating self-sustaining salad patches that keep giving year after year. I grow this all year round here at Garden Ninja HQ in my greenhouse!
Pak Choi and other Asian greens excel when sown in September, as they appreciate the moderating temperatures and reduced day length. ‘Green Fortune’ produces succulent stems whilst ‘Purple Top’ adds ornamental appeal to vegetable plots.
Chinese Cabbage varieties form tight heads when sown now for autumn harvest. These vegetables require consistent moisture but reward careful cultivation with exceptional flavour and texture.
Broad Beans can be sown in September to overwinter and produce an early crop. Again, grow these in empty loo rolls as they root better and don’t like shallow pots or containers. The broad beans are quick to establish before temperatures fall, when they enter dormancy, but resume growth again as soon as temperatures increase again in spring. Try ‘Aquadulce Claudia’, which performs brilliantly from autumn sowings.
Hardy peas can be sown in September to overwinter and produce an early crop. Choose winter-hardy varieties like ‘Douce Provence’ or ‘Meteor’ and cover with a cloche when frost is forecast.
Garlic planted now benefits from the cold stratification winter provides. Garlic can be planted from September, and will overwinter easily, providing you with an earlier harvest in summer. It’s said that garlic needs a decent cold spell in order to separate the cloves, so sowing now could yield better results than from spring sowings. Plant cloves 2.5cm deep and 25cm apart in well-prepared, fertile soil.
Parsley sown in September establishes beautifully and provides fresh leaves throughout winter. Flat-leaf varieties like ‘Giant of Italy’ offer superior cooking flavour, whilst curly types provide attractive garnish potential.
Coriander thrives in September conditions, with moderate temperatures preventing rapid bolting. ‘Leisure’ offers slow-bolting characteristics perfect for autumn establishment.
Winter Savory sown now develops into compact perennial bushes providing aromatic leaves throughout winter. This Mediterranean herb offers pine-like flavours that complement winter bean dishes perfectly.
September presents the optimal window for establishing new fruit plantings. Container-grown fruit trees and soft fruit bushes planted now develop extensive root systems before dormancy, resulting in earlier cropping and improved long-term performance.
Apple Trees planted in September have significant advantages over bare-root winter plantings. Container-grown specimens establish quickly in warm soil, allowing extensive root development throughout autumn. Choose disease-resistant varieties like ‘Discovery’ for early cropping or ‘Egremont Russet’ for exceptional flavour.
Plum Trees also work well when planted in September from containers, as these stone fruits can be temperamental when moved during dormancy. Victoria’ remains the reliable choice, whilst ‘Opal’ offers exceptional disease resistance.
Plant strawberries now and they’ll establish well in the still-warm soil, before going dormant in winter and fruiting from mid-spring. Plant bare-root strawberries into well-prepared, fertile ground, around 35cm apart. ‘Cambridge Favourite’ provides reliability whilst ‘Mara des Bois’ offers exceptional flavour.
Raspberry Canes planted now establish vigorous root systems supporting heavy cropping. Autumn-fruiting varieties like ‘All Gold’ and ‘Heritage’ can even provide small crops in their first autumn.
September plantings succeed or fail based on the quality of soil preparation. Late summer soil often requires rejuvenation after the demands of the growing season, especially if you’ve had hungry vegetables, fruit, or shrubs that have drained the soil of nutrients, which is why September is the month of MULCH!
September soil can be deceptively dry beneath the surface, despite autumn rains having begun. Just dig down one spade’s depth and you will see whether the soil is moist or simply dry and dusty! Deep watering during planting ensures that your plants will thrive. You can’t really overwater container-grown plants or divisions at this time of year, apart from seedlings, which can suffer from damping off. Consider using simple irrigation systems, such as seep hoses, for newly planted areas.
September plantings benefit from modest soil improvement rather than heavy feeding. Soil may also need enriching after a summer of growing, so dig in lots of well-rotted compost or manure, which will feed your new plants and also help the ground hold on to moisture.
September is the ideal time to mulch your garden flower beds, raised beds, kitchen gardens and other productive areas. Organic peat-free compost, leaf mould or mushroom compost can be used to top dress flower beds. This acts as a slow-release feed, prevents weed seeds from germinating and retains moisture. It’s probably the best thing you can do to improve soil quality naturally.
Cold frames can be invaluable at this time of year, as you can protect plants from light frost and heavy rain, which can lead to rotting. Invest in quality protection now, such as fleece, cloches, and cold frames, which become essential as autumn progresses. Cold frames are incredible as they offer a small protected environment for seedlings and even potted plants during the colder winter months. Get them built now to save you from doing it in the freezing cold!
Even experienced gardeners can fall into September traps that reduce establishment success.
September’s perfect conditions can lead to overenthusiastic planting programmes that become overwhelming. Start with manageable areas and expand gradually rather than attempting a comprehensive garden transformation in one season. You can always grow more next year, but if you end up frustrated trying to manage hundreds of plants, it can put you off gardening, which we don’t want!
September plantings require increasing protection as autumn progresses. Establish protection strategies before they become essential rather than scrambling during the first frost warning. Such as preparing cold frames and monitoring the weather and garden pests.
The biggest complaint I get from new gardeners is that their spring bulbs fail to flower, fall over or look sickly when they emerge in March. 99% of the time, this is down to the fact that they are planted too shallow. As a result, their roots struggle to absorb moisture and nutrients from the soil. As a rule of thumb, plant all bulbs 3 times their depth, and for Allium bulbs, even deeper.
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September gardening rewards careful planning with spectacular results, providing satisfaction throughout the next growing year. This often-overlooked month allows you to steal a march on next year whilst enjoying perfect outdoor conditions.
Whether sowing sweet peas for next spring’s cutting garden, establishing fruit trees for future harvests, or creating the foundation for stunning spring displays, September efforts create the backbone of gardening success. After all, who doesn’t want a garden bursting with early flowers and fresh produce whilst neighbours wonder how you manage such spectacular results?
Get out there Ninjas, and make September your secret weapon for next year’s garden triumph!
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