September is the garden's second spring. The soil still holds summer's warmth, the nights cool down and the first rains wake up everything that goes into the ground, so a single month has room for the autumn vegetables, the herbs, the bulbs that will flower in spring, the winter bedding plants and the year's best lawn sowing. Everything that started with the August preparations, from ordering bulbs to starting seed trays, now goes into the soil. Here it is, job by job.
Vegetables to sow and plant in September
The winter vegetable garden is built now. Leafy crops prefer the coolness and germinate fast in the still-warm soil, while brassicas go in as ready seedlings so they mature before the hard cold.
| Vegetable | Sow or transplant | Harvest |
|---|---|---|
| Lettuce, rocket, spinach | Direct sowing or trays, in batches every 2 weeks | From October and through winter |
| Cabbage, broccoli, cauliflower | Transplant ready seedlings | Late autumn to winter |
| Carrot, beetroot, radish | Direct sowing in deep, loose soil | Radishes in a month, the rest in 2 to 3 |
| Spring onions, leek | Sowing or transplanting | Winter to spring |
| Garlic | Plant cloves from the end of the month | Early next summer |
On the balcony, leafy crops do well in 20 cm-deep troughs with good potting mix and morning sun. Two notes for the end of the month. Broad beans and peas are sown from late September into October, timed to sprout with the first rains, and spinach sown too early, while days are still long, can bolt prematurely, so in warm regions it waits for the second half of the month.
September is also strawberry month. Young plants go into their final position from mid-month, in full sun and light, rich soil, 25 to 30 cm apart, so they root through autumn and crop heavily in spring. Autumn planting almost always beats spring planting in terms of the size of the first harvest.
Herbs
September belongs to parsley, dill and coriander, all sown directly and all happier in autumn coolness than in summer heat, which sends them to seed. Parsley is slow, often taking 2 to 3 weeks to germinate, so the soil stays evenly moist and patience is part of the recipe. Chives are sown or divided, and mint is divided now, giving the new sections time to root before winter.
The spring bulbs go into the ground
The big September job is the autumn bulbs, planted from now until November for a relay of flowers from January to June. The freesia traditionally opens the season, followed by crocuses, daffodils and the fragrant hyacinth, while the tulip waits for the soil to cool a little, from mid-month onward, with pre-chilling in the refrigerator in mild-winter regions. The bulbous iris is planted now too, and late summer is also the moment for rhizomatous irises, set with the rhizome half-exposed, and for dividing their old, congested clumps.
The rules are the same for all of them. Free-draining soil, a depth of two to three times the bulb's height with the pointed tip up, and one thorough watering after planting.
Bedding flowers for winter colour
The summer bedding is winding down and the winter cast takes its place. Pansies are planted from now until November and flower all winter, cyclamen return to pots and shaded beds, and chrysanthemums build toward their autumn peak. Alongside them, dianthus, alyssum, verbena and asters go in as ready plants for colour within weeks, and the marigolds started in August seed trays move to their final positions. For a bed that never sits empty, the full plan lives in the guide to flowers that bloom all year.
The best month to sow a lawn
For lawns, September is the month of the year. The soil is still warm, so seed germinates in 7 to 14 days, the cool nights and first rains keep the surface moist, and the young grass roots deeply before winter, without the heat and weed pressure of a spring sowing. The same goes for overseeding the patches summer wore out. Scratch the surface open, spread a thin layer of soil or compost, scatter the seed, press it in lightly and water daily with a fine spray until it germinates.
The rest of the month's jobs
September also carries the maintenance that sets up the new season. Spent rose blooms are removed for one last autumn flush, congested perennials from yarrow to bee balm are divided and replanted, and beds are enriched with compost before the plantings. On trees and shrubs, hard pruning waits for winter, and only dead or broken branches come off now.
Frequently asked questions
What vegetables can I sow in September
Lettuce, rocket, spinach, carrots, beetroot, radishes, spring onions and leeks directly, and cabbage, broccoli and cauliflower as ready seedlings. Garlic cloves go in from the end of the month, and broad beans and peas from late September into October.
When should spring bulbs be planted
From September to November. Freesias, crocuses, daffodils, hyacinths and irises go in from now, while tulips prefer mid-September onward, once the soil has cooled.
Is September a good month to sow a lawn
It is the best one. Warm soil germinates the seed in 7 to 14 days, cool nights hold the moisture, and the grass roots before winter with far less weed pressure than a spring sowing.
What flowers can I plant in September for winter
Pansies, cyclamen and chrysanthemums are the core winter trio, joined by dianthus, alyssum, verbena and asters in beds and containers.
Can I still sow herbs in September
Yes, September is ideal for parsley, dill, coriander and chives, which prefer the coolness, while mint is divided now.
Is September too early to plant strawberries
No, it is the right time. Plants set out from mid-September root through autumn and produce a noticeably bigger first crop than spring-planted ones.
Important notes
Every garden runs on its own climate, so shift these dates earlier in cold regions and later in mild ones, and treat the guidance above as a general starting point for the month.
References
- Royal Horticultural Society, September gardening jobs.
