The plants are thriving in here in my polytunnel.

Who would be crazy enough to think about overwintering lettuce in Sweden? Well, I think you know the answer. I got the idea from an English gardener on YouTube. The climate is, of course, a bit more merciful over there than it is here. They have no issues overwintering lettuce from what I have heard. But up here in Scandinavia, does it really work?

The short answer is yes. It works really well. I have tried it for a few years now and I can tell you that overwintering lettuce is so convenient. The overwintered lettuce will give you a much earlier harvest than the lettuce you sow in spring. For us, it means that we don't actually need to buy any leafy greens for our salads or sandwiches from March/April.

I sowed this bunch in a plug tray (150 in one tray) and planted them in soil fertilized with bokashi compost.

I'm protecting my lettuce with all and all four layers of plastic and row cover.

How I do it

Overwintering lettuce up here in zone 3 is actually easier than you might think. The most important things to think about is to pick cold-resistant varieties, plant them at the right time and then protect them against the cold.

• Sow the lettuce at the end of August or the start of September.
• Replant the little plants in the polytunnel beds in October.
• Make sure to protect the plants from the cold, from December forward or when the temperature creeps below freezing in the polytunnel.
• The plants start growing when the light comes back in the middle of February.
•  When the lettuce starts growing, it's time to start watering and airing the plants out so it doesn't get too moist.
• I water my plants regularly from mid-March forward.

The plants have been growing nicely under the row cover all winter. They froze a few times but have been doing really well since. The picture was taken in January.

Read more: My favorite lettuce

Which varieties?

Plenty of varieties are described as cold-resistant, and this is definitely what you should go for when you want to overwinter lettuce. Many varieties work, for example, oak leaf and romaine lettuce. I decided to overwinter these varieties this year: Little Gem, Intred, Red Salad Bowl, Salad Bowl, Cegolaine, Cerbiatta, and Linaro.

More about overwintering lettuce: Overwintering lettuce in a polytunnel

The light returns in the middle of February when the plants start growing again. The pale green lettuce is called Little Gem, it's a tiny romaine variety.

Protection from the cold

They say that every protective layer is equivalent to improving the temperature with an entire cultivation zone. I decided to protect my lettuce like this: polytunnel, a small polytunnel inside the larger one, pallet collar bed with a lid and at last a row cover. All in all four layers.

I put pallet collars on the bed and planted my lettuce in them. The collars protected the plants against the cold that would have seeped in from the sides. This turned out to be a good solution.

I want to point out that I didn't use any extra heat in the polytunnel when I overwintered my plants. They can take the cold, even a frozen layer of topsoil in the bed and temperatures down to -22 (-30 degrees Celsius) outside the polytunnel.

This red Little Gem variety is called Intred. This is my first time growing it and every single one I planted in October has survived.

Plenty of little plants

We are a large family that really enjoys leafy greens. So, naturally, we need to harvest quite a bit to make the effort worthwhile. That's why I always grow a lot of plants. I have around 200 plants in here.

Do you really need that many? Well, I want to harvest my lettuce as early as I can. The leaves are not very large at this time though so I solved the problem by growing plenty of little plants that I can harvest leaf by leaf every other day. I harvest bigger batches when they start growing though, this keeps my lettuce small which means that I can keep them in tight rows.

The lettuce grows so quickly now that I need to harvest it every day. I leave some Romaine plants untouched for now so that I can harvest them in a few weeks. But most of them are harvested more frequently.

The plants grow so quickly and we need to eat a lot to keep up with it all!

Tips for beginners

If I was a beginner and saw the picture of the bed in April, I probably would have thought that this type of project was for professionals only. Because it looks so difficult and complicated, and so many plants growing there!

It's not as difficult as it might seem! On the contrary, it's quite easy. The plants basically take care of themselves in winter, as long as the foundational work has been taken care of. And it's all worth it in early spring when this gorgeous green mat starts to emerge in my polytunnel. If you feel inspired by these pictures, I definitely think you should give it a try. There's nothing more satisfying than making that first super early spring salad. This lettuce is delicious with most dishes, just pair it with some pea shoots and ramson. Yum!
/Sara Bäckmo