In October you can still sow Chinese cabbage, spring onions, Chinese broccoli, red lettuce, choy sum and pak choi under cover in a greenhouse or polytunnel. They will germinate while days under glass still reach about 20°C and nights hold at 9 or 10°C. Don’t expect full-size veg from them. Sow for baby leaves you can pick through winter for salads, soups and stews.
I’m in the south-west of the UK, where it runs a bit warmer and a bit wetter than most of the country. If you garden somewhere colder, check what your own greenhouse is doing at night before you sow.
The six crops at a glance
| Crop | Why it works in October | My plan for it |
|---|---|---|
| Chinese cabbage | A good doer that grows in low light | Plant into the polytunnel soil, pick as baby leaves at 5–8cm (2–3in) |
| Spring onions | Germinate anywhere from 5°C to 30°C | Keep sowing after a poor summer with them |
| Chinese broccoli (kai lan) | Hardy, and makes a big leafy plant if you let it | Polytunnel soil, leaves for hearty stews |
| Mixed red lettuce | Lettuce goes through winter fine here | Backup to the outdoor beds, picked as needed |
| Choy sum | Grows really fast as a leafy green | One plug in the tunnel to see how big it gets |
| Pak choi | Past its outdoor sowing window, fine under glass | Large container in the greenhouse, baby leaves first |
Why October still works under cover
Heat is not the problem yet. My greenhouse hit about 22°C one afternoon this week and was down to 9°C the next morning. That swing is still inside the range these seeds need to germinate.
Light is the problem. Light is a plant’s food, and as the levels dip everything grows more slowly. I’m not using grow lights yet, so I plan around the slowdown instead of fighting it.
That is why the target is baby leaves, not big beautiful veg. I let the leaves get to about 5–8cm (2–3in) tall and then start picking. A handful for a salad or a soup is the win at this time of year.
The other reason is you. It is very easy to sit under a blanket with the telly on all winter. A few trays of seed give you a reason to get out there.
The six crops
1. Chinese cabbage
This is the first one in because it is a good doer and grows in low light. A month after sowing it is a sturdy little plant, ready to go into the polytunnel soil. From there I pick it as baby leaves and leave the plant to keep producing.
2. Spring onions
Spring onions germinate anywhere from 5°C to 30°C, so temperature is not holding them back in October. I’m sowing them again even though they have been a story of failure for me all summer. More on that further down.
3. Chinese broccoli (kai lan)
Think of this as a very big spinach or broccoli leaf. Left alone in the tunnel soil it makes a large, very green plant, and the leaves are great in hearty stews. You can harvest it young. If you see flowers on it, it is definitely time to pick.
4. Mixed red lettuce
My outdoor beds are already full of lettuce that will go through the winter fine. This sowing is the backup. It goes in the ground under cover and I pick it as I need it. Next month’s seedlings will be a bit shorter than a summer sowing because of the light.
5. Choy sum
Choy sum grows really fast and makes a good leafy green. I have always eaten it young, so I have never seen one reach full maturity. This year one plug is going in the polytunnel to find out what it does. Don’t be afraid to experiment like that.
6. Pak choi
The packet says the last outdoor sowing is July. Indoors under glass we are still good to go. I sow this one in a large container and keep it in the greenhouse with my other pak choi. Baby leaves first, and if a mature plant comes of it, all the better.
How to sow them
All six get the same treatment.
- Fill your tray, pot or tub with compost. A seed tray is fine if you are planting out later. Use a big tub or trug if the plants will stay in the greenhouse. [Photo: shot 5, the kit laid out]
- Sow thinly over the top. Not too many, just enough to keep you going. I sow for a family of four who eat a lot of veg, and I still catch myself tipping in too much. [Photo: shot 4, hands sowing]
- Sieve a very light covering of compost over the seed. These are tiny seeds. A dusting is all they need. [Photo: shot 6, the sieve]
- Water them in. [Photo: shot 7]
- Take the seed packets back indoors. See the condensation note below.
- Grow on for about a month. By then the seedlings are big enough to plant into the polytunnel soil, or to prick out and grow on in tubs. [Photo: shot 8, the month-old plants]
- Start picking at 5–8cm (2–3in). Take leaves as you need them and leave the plant in.
What usually goes wrong
- Spring onions that never show. Normally I nail these every time. This summer I have had one or two come up and not many more. It is not a temperature problem, given they germinate from 5°C to 30°C. I suspect the compost has changed, but I don’t know. If a sowing fails, it is probably the seed or something else outside your control, not you. Sow again.
- Sowing too thick. Easy to do with seed this small. I did it with the Chinese broccoli.
- Slugs on the lettuce. Expect some damage once it is in the ground. Oversow, so that whatever the slugs take, you still have the rest.
- Seed packets left in the greenhouse. I left mine out overnight. A drop from 22°C to 9°C puts condensation over everything, packets included. We are into condensation season in the UK now, so take your seed indoors.
- Slow growth. Nothing is wrong. Light levels have dipped and the plants are feeding on less of it.
- Yellowing leaves in containers. The plants have used up the nutrients in the compost. Feed with a bit of liquid seaweed to boost the green leaf.
What happens next
Sow now, while the greenhouse is still warm by day. In about a month you will have plants the size of the ones I show in the video.
In the polytunnel, my tomatoes are still in. I’ll pick the last of them, clear the plants out and redo the tunnel. The Chinese cabbage, Chinese broccoli, red lettuce and choy sum then go into the soil.
If you only have a greenhouse, that is absolutely fine. Grow in big tubs or good-sized trugs, sown thinly or pricked out, and pick from them for your soups. All six of these are hardy, so they keep going under glass until the frosts start to bite.
Common questions
Is October too late to sow seeds in a greenhouse?
No, not for these six. Mine germinate with days around 20°C and nights at 9 or 10°C. What changes is the speed. Growth is slow, so plan on baby leaves and treat anything bigger as a bonus.
Do I need grow lights to sow in October?
I’m not using any yet. Without them the plants simply grow more slowly, because light is their food and there is less of it. If you are happy picking small leaves, you can manage without.
Can I grow winter salad leaves without a polytunnel?
Yes. A greenhouse on its own is fine. Sow thinly into big tubs or trugs and pick straight from them, or prick a few seedlings out to grow on.
The packet says the last sowing is July. Can I still sow pak choi?
That date is for sowing outdoors. Under glass you are good to go in October, and it does well as baby leaves in a large container.
Why are my greenhouse seedlings turning yellow?
If they are growing full-time in a container, yellowing usually means they have used up the nutrients in the compost. A feed of liquid seaweed greens them up again.
How much seed should I sow?
Less than you think. A thin scatter per tray is enough to keep a family of four going. Lettuce is the exception. Sow extra so the slugs can have their share.
Keep going
The seeds I used are linked here: https://justseed.com/?ref=Veggiepatch
More from the site:
If you want to keep the brain ticking over winter, the free Growers Academy app has video lessons and little quizzes on growing veg. You will find it at Get the Free App.
If a tray fails, it fails. You were out in the garden growing something, and that is the point.