What to sow now – September

There is still sow much that you can sow for cropping over winter and into the spring, for delicious harvests grown undercover and outside.
September is like a second spring, a busy sowing and planting month, but unlike actual spring every day is shorter, there is less daylight and temperatures are dropping. In the spring there’s (almost!) always time to catch up: your lettuce didn’t sprout? Never mind, sow some more. But in September timing is far more important, so that plants can be in the ground and established before winter.

Polytunnel, February 2020

Depending on the kind of vegetable or herb, and the weather I’ll start picking these plants towards the end of the year (carrots and Florence Fennel from March onwards). If the weather is mild and bright, salads and other leaves will be a bit earlier. If it is cold and dismal, growth will slow down.

This week I’ll be sowing the last seeds of the year, except for garlic (October) and broadbeans (November). Most will be sown in the greenhouse and will be ready to be planted out as transplants in around 5-6 weeks.

There’s a list of everything I am sowing in September at the end of this blog!

I sow lettuce, Florence fennel, pak choi, brassicas and endives into a seed tray and prick out into modules once they have sprouted and are large enough to handle to grow on as transplants. This saves space – I can sow a whole winter garden in just a couple of seed trays – and means I can choose the sturdiest seedlings to grow on. Making grooves in the compost (see photo) helps to keep the seedlings in a straight line, which makes identifying the varieties easier, and prevents them from getting muddled up with their neighbours.

Everything else listed here (except the seeds that are direct sown in the ground, such as carrots) are multi sown in modules, usually 2-3 seeds per module (6 – 8 for spring onions). Larger plants such as chard will be thinned to one seedling before planting out.

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It can be tricky deciding how much to sow and grow. I always sow more than I need, so that I should have enough plants for the garden (as I mentioned earlier, time is so important in the autumn, there is less of an opportunity for catching up). Vegetables and herbs are less productive over winter, so I grow about 1 1/2 times as many plants as I would in the summer.

February harvest

So for example, if 10 spinach plants are enough for my family during spring and summer months, I’ll grow 15 spinach plants over winter.

Growing plants in modules first also makes it easy to intercrop, popping new plants between existing crops which will be harvested later on, such as between tomato plants in the polytunnel or summer planted lettuces at the allotment.

For beds where it’s not so easy to intercrop – main crop potatoes, sweetcorn, squash etc – growing transplants means that new plantings can be growing as the existing vegetables mature, so after the bed is cleared and replanted, the veggies have already been growing for several weeks.

September sown Florence Fennel in late February

You can choose which transplants to use, discarding any that look weak or have been damaged, another great benefit of growing transplants. Surplus plants can be composted or, if you can’t bear to compost one of your leafy babies, pop them in odd corners as a “green manure”. The roots will benefit the soil life and, if you don’t eat the plants yourself, they make excellent bulk for the compost heap in the spring. If you can, leave brassicas to flower which will encourage beneficial predators to your garden and provide welcome forage for bees and other early emerging insects in the spring.

If you don’t have a polytunnel or greenhouse, make a cloche for plants which will benefit from the extra protection from extremes of weather out of polythene over cloche hoops or a simple frame made from tying bamboo together. Ask locally for large sheets of polythene – the wrappers for double mattresses are very useful! This does not stop freezing, but all of the plants listed here will cope with some freezing during the winter months. If there is a long period of cold, or very low temperatures, slip some horticultural fleece underneath the cloche to make it cosier. You will need to remember to water under the cloche of course.

winter salads interplanted between summer cropping veg

Seeds to Sow in September  

Directly into the soil

Carrots – mostly Nantes, Manchester Table Carrot and Autumn King – all undercover (polytunnel, greenhouse, cloche, Vegepod)

Carrot seed doesn’t keep well so if you have the space try some other varieties.

Green manures – outside –  field beans, agricultural mustard Sinapsis Alba, Caliente mustard and crimson clover.

I use these because none need to be dug in. The mustards and clover will die off in the frosts and the field beans are cut at ground level before harvesting, useful composting materials. There isn’t much space for green manures as the beds are mainly full, however I use them underneath fruit bushes and places like that, as well as any odd spaces.

land cress, claytonia and purslane – undercover and outside

Radish – undercover and outside – winter hardly varieties: French breakfast, Green Luobo, Black Spanish Round

For growing undercover – these are almost all for my polytunnel and greenhouse. If you don’t have these, make cloches from hoops and polythene. They all appreciate some protection.

I grow lettuces, onions, rocket, mustards, oriental greens and brassicas outside over winter in the beds at Hauser and Wirth with no protection and although frost and snow knocks them back, they still produce a worthwhile crop in the spring. Worth considering if you live in the milder areas of the UK. Riskier in colder, windier and wetter parts, where I would recommend using a cloche cover.

Lettuces – mostly Grenoble Red (home saved seed) plus Bronze Arrow, Winter Marvel, Jack ice, Red Iceberg, Winter Marvel

Onions – white lisbon, read beard, bunching onion “Kyoto market”, feast.

White Lisbon is especially good value as it produces slender onions ideal for stir fries and salads and then, in later spring, small round onions for cooking. I have found here in Somerset that all the spring onions over winter outside well too. Make them cosy with some fleece or polythene when the winter starts to become harsh.

Herbs – dill, coriander, chervil, parsley (curly and flat leaf), rocket, wild rocket, wasabi rocket

Dill can get knocked out by really bad weather even under cover, the rest are more resistant.

Mustards and oriental greens – red mustard, red frills, Osaka purple mustard greens, Nine headed bird mustard, Golden Frills, Red Frills, Dragon’s Tongue, pak choi, and many others

Wonderful for salads (pick leaves small) and stir fries. In the spring, leave some to flower to bring in the beneficial predators.

Pak Choi: Vibrant Joy and Tuushou F1, Green Boy, Santoh Round Leaf Yellow, Tai Sai White Stem

Spinach – viroflex giant spinach, Medania

Chard – any swiss chard will be fab

Beetroot for leaves – any, they are unlikely to produce roots before bolting, although sometimes you will get baby beets, but will make delicious leaves for salads and cooking.

Endives – En Cornet de Bordeaux, Fine Maraichere, Bianca Riccia da Taglio

Mizuna – Red and pink stem

Funky brassicas and greens – spigariello, Huazontle, Rapa Senza Testa, San Marzano, Green Days Eighty, Wa Wa Cai Choi, Hon Tsai Tai, Broccoli Raab, all kinds of kale: Cavolo Nero, Red Russian, Dazzling Blue, Red Ruffled, True Siberian, Red Ruble

Most of the strange sounding ones are from Real Seeds. I grow 2-3 of each variety and oh the joy of the leaves and shoots during the winter months. They are sweeter and more tender in the polytunnel/greenhouse but will grow outside too.

Spring Cabbage – Durham Early, Greyhound, Piacenza, Wheelers Imperial, April

All of these can go outside too but will be later than August sown spring cabbage and may bolt before hearting – not a great worry as they make fabulous spring greens. Under cover, they usually heart unless we have bonkers warm weather in February again!

Peas – Havel, Douce Provence, Oskar

Short growing over winter peas are ideal for earlier pickings. These will also grow outside. I prefer peas that don’t need sticks because the polytunnel is also used as a place to dry my washing in the winter (!) but I will try a few taller varieties too.

Plus left over peas – any variety – for pea shoots. I mix up odds and ends of seed packets and sow 3 into a module, or broadcast over a large pot or tray, for picking as salad pea shoots, which are also tasty in stir fries. Fine on window sills and green house shelves, too – a very versatile crop.

You can grow these cheaply from marrow fat peas from supermarkets, but they are sweeter and more vigorous from sugar and regular peas.

Florence fennel – Solaris and Finale are F1 varieties which are very reliable over winter. I also grow Mantovano and Colossale open pollinated Florence fennel.

8 thoughts on “What to sow now – September”

  1. Thank you.

    Lots of good and new to me advice re numbers of plants etc.

    I also didn’t realize I could sow white mustard in September. And the fact I could use it simiarly to cress makes it sound well worthwhile.

    Thank you!


    Good to meet you at the intensive weekend. Looking forward to your new book.

    We njoyed your garden (and your son’)s at Hauser and Wirth on the Sunday afternoon. Thanks for the advice. Amazing place.

  2. Hello Stephanie , Yes all my seedlings are popping up now in our Veg Trug . It’s so good to see them germinating isn’t it ! I always grow Pak choi , but I really must try more of those Oriental Greens . I will write it down in my little red veg garden book . I hope the lovely Autumn Sun is shining in your part of the world ! Debbie 🙂 x

    1. Stephanie Hafferty

      Thank you Daisy. It was sunny here yesterday but gloomy here today. I love pak choi, so versatile as a raw and cooked veggie.

  3. What a great list Stephanie, but I was surprised that your growth rate only drops to 2/3 if your summer growth, to keep me going over winter I often need 2-3 times as many plants as summer : all the best – Steve

    1. Stephanie Hafferty

      Could be a location thing, I am in South Somerset, but 50% more is usually about right until mid-March when everything grows like crazy and it is too much!!

  4. Your polytunnel is impressive. I’m thinking of buying one for myself or building a greenhouse. Which option is better, in your opinion? I know it’s good to have such place especially in colder days. And also when it’s a bit automatized it helps you to save time. In September I don’t sow so many plants as they wouldn’t survive in my climate. My must-grow is lettuce I buy on https://gardenseedsmarket.com/lettuce-seeds-en/ but when it’s getting colder I take it inside.

    1. Stephanie Hafferty

      Thank you Jean. It very much depends on space and budget. Greenhouses are more insulated and long lasting, but they are expensive for larger spaces. There is no way I could afford a 12 x 40ft greenhouse!

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