O Sweet September Rain

What Seeds to Sow in September – Keeping the Garden Growing Into Winter

September can feel like a bit of a turning point in the garden. The days are getting shorter, the evenings noticeably cooler and some of the summer crops are looking  tired or have finished already. But I’ve learned not to think of September as the end of the growing season. There is still plenty that can be sown, and some of the things I could sow now, will keep me harvesting well into autumn, through winter and, with a bit of luck, into the following spring.

For me, September is about making the most of every bit of available space. As one crop finishes, I’m looking at the space it leaves behind and asking myself what I can sow next.

What I’m sowing outdoors in September

There are still plenty of vegetables that can be sown directly into the soil. I particularly like this time of year for salad crops because they grow quickly while there is still some warmth in the soil, but the cooler conditions mean they are less likely to bolt.

Herbs

Some herbs can be direct sown now too; coriander, dill, flat leaved parsley and chervil for fresh tasty leaves before the frosts curtail growth. Perennial varieties of chamomile can be sown in trays or pots to plant out later.

Salad leaves, radish and quick crops

Make last sowings of quick-growing salad leaves and radishes in September. These are ideal for filling gaps where something else has finished.

Also sow winter lettuce, land cress and corn salad (lamb’s lettuce). Not only can they provide leaves for picking through autumn but, depending on the weather and protection available, well into winter.

I find it much more satisfying to have a small amount of fresh salad growing outside than to think the garden has finished producing food simply because summer is over.

Spinach and Oriental greens

September is also a good time to sow Perpetual spinach and Oriental greens such as Pak Choi, Mizuna and Mustard.

These are crops I really value because they are relatively quick, productive and versatile. Young leaves can be for salads, while larger leaves can be picked and cooked.

The cooler weather can actually work in their favour. Unlike during the heat of summer, there is much less worry about everything rushing to flower (bolting) before I’ve had a chance to eat it.

Turnips and Spring onions

Turnips are another useful crop for making the most of a patch of ground that might otherwise sit empty over winter. Winter-hardy spring onions such as ‘Winter Hardy White Lisbon’ are worth considering too. September sowings can overwinter and provide an early crop the following spring.

There is something particularly rewarding about sowing a crop now knowing that it will quietly sit there through the colder months before giving me an early harvest when there isn't much else ready.

Don't forget overwintering crops

September is also a good time to continue sowing vegetables that are intended to overwinter and mature next spring.

Kale, spinach, winter lettuce, turnips and Oriental greens can all earn their place in the garden at this time of year, alongside onions, such as Toughball, or Japanese onion Hi Keeper for cropping next year.  

Of course, the weather will always have the final say. A mild autumn can encourage lots of growth, while a particularly cold or wet winter can slow everything down. But choosing hardy varieties and giving plants the right protection gives them a much better chance.

What I’m sowing under cover

If you have a greenhouse, cold frame or even a few cloches or sheltered place, September gives you some extra opportunities.

I find that a little protection can make a surprisingly big difference at this time of year.

If your garden isn't completely blasted by autumn and winter gales, covering green leaf crops such as salad leaves, spinach and pak choi can extend the cropping season and protect them from heavy rain and the worst of the weather. It isn't necessarily about keeping plants warm. Sometimes it is simply about giving them a little shelter from the elements.

Spring cabbages

Early September is also the time to sow spring cabbages such as ‘April’ and ‘Durham Early’ into modules under cover or on a windowsill to germinate.

I like sowing into modules at this time of year because it gives the young plants a little more protection while they establish. They can then be planted out when they are large enough and the conditions are suitable.

It is another example of thinking ahead in the garden. What I sow in September may not be something I harvest for months.

Autumn Sown Flowers

September isn't just about vegetables. There are quite a few flowers that can be sown now, either under cover or directly where you want them to grow. Sow now for stronger plants.

Sow hollyhocks, violas, lupins, aquilegias, verbascums, heleniums, perennial salvias, hardy geraniums and delphiniums in pots or trays and keep them in a cold frame or sheltered place over winter. They can then be planted out in spring. I particularly like autumn sowing for hardy plants because it gives them plenty of time to establish. I'm not expecting a spectacular display immediately. Instead, I'm giving the plants time to develop a good root system so that they are ready to grow away strongly when spring arrives.

Choosing varieties that can cope with drier conditions.

Our summers seem increasingly unpredictable, and I don't want a garden that needs constant watering to survive. Some of the flowers to sow in September are particularly suitable for drier summers, I’m thinking California poppies, cornflowers, nigella, verbascum and perennial salvias. Once established, they can cope with considerably drier conditions than some of the thirstier perennials. Of course, newly sown seeds and young plants are a different matter, they’ll need watering while their roots are developing. Getting plants established before the heat of summer arrives can give them a much better chance of coping when the weather turns dry.

Plants that can cope with heavier soils in drought.

If, like me, you're gardening on heavier clay soil but are also becoming increasingly conscious of drought and summer watering, then top choices are rudbeckia, yarrow and echinacea. Yarrow is particularly robust for drier conditions, while rudbeckia and echinacea can also become remarkably resilient once established. With all three, though, I need to remember that drought tolerance comes later, newly germinated seedlings still need enough moisture to establish good root systems. I'll sow them into trays or modules rather than putting them straight into the garden. The trays can then spend the winter somewhere cool and sheltered, (such as a cold frame or unheated greenhouse). I'm not trying to push them into growth now; the aim is simply to give the seeds and young plants a protected place to spend the winter before they really get going in spring.

Sowing flowers directly into the garden

There are also some flower seeds that are best sown directly where I want them to flower.

Autumn sowing can produce bigger, more robust plants because the seedlings have a long period in which to establish before the spring growing season really gets going.

Some of the flowers I might try are calendula, annual poppies and California poppies directly into the ground for flowers next year. Tap-rooted they don’t like being transplanted. Others you could also sow include ammi majus and larkspur, along with hardy annuals such as nigella, cornflowers and poached egg plant depending on your soil and location.

One of the advantages of direct sowing is that I don't have to find space for lots of pots and trays. The plants establish where I eventually want them to grow, although I do need to make sure I can recognise the seedlings and keep them weed-free while they are small!

Don’t leave empty ground bare; green manures

One of the things I have started doing is sowing green manure into empty spaces. I've become much more aware of this over time. Good gardening isn't just about growing plants; it's also about looking after the soil that those plants depend on.

If I've finished harvesting a bed and don't have another crop ready to go in, I don't necessarily want to leave that soil bare throughout winter. Green manure can help protect the soil, improve its structure and prevent weeds from taking over. It also means I'm thinking about the health of my soil rather than simply what I can harvest from it today.

So, rather than seeing an empty bed in September as a job finished, I see it as an opportunity.

September is really about planning ahead

For me, September is one of those months when the garden becomes a little more strategic.

I'm harvesting what I can from the summer crops, clearing plants that have finished, filling gaps with quick-growing salads and thinking about what I want to eat over the coming months.

Some things I sow now will give me something to pick within weeks. Others will sit quietly through winter and reward me next spring.

That's what I enjoy about gardening. There is always something to do, and the garden is rarely as “finished” as it might first appear.

If you have a spare patch of soil in September, don't automatically leave it empty until spring. Have a look at what could still be sown. A few clumps of winter lettuce, spinach, Oriental greens or corn salad might seem like a small thing now, but those little sowings can make a big difference when winter arrives and fresh produce from the garden becomes much harder to find.

And, of course, there is nothing quite like going outside on a cold morning and finding that something you sowed months earlier is still there waiting to be harvested.

“I'm not just choosing plants that survive my soil; I'm increasingly choosing plants that can cope with the weather we're getting.”