Written by Spirekassen 19 Aug 2022 11:52

Start your winter cultivation now


Photo & text: Christine Wiemann

I might be ruining your summer holiday. I know it is only August, but you should start thinking of your winter cultivation now. We all know it. The greenhouse will quicly be full of garden furniture, the grill and other things that need to be protected during winter. That is a shame. Instead use the greenhouse for what it was meant to be, which is cultivation of plants. Did you know you can cultivate greens in the greenhouse during the winter months. In the next months you can slowly begin your winter cultivation and use the space you previously had for tomatoes, cucumbers and chillis.

Keep up with the seasons in the greenhouse

First thing is to follow the time of the seasons and let things take their time. In spring and summer everything grows fast in the greenhouse due to lots of sunlight and heat. It is slower in autumn and in winter. The lack of heat and sunlight slows down the plant growth. And when you cultivate during winter, you will also need to choose other plants to cultivate than the ones you had during summer.

The definition of winter cultivation

Cultivating in the greenhouse during winter is the period from September to the end of February the following year.


What you will need

  • A greenhouse without any form of external heat source
  • Winter sun and rainwater
  • Planting soil
  • Seeds for winter cultivation
  • Crop cover cloth


Climate-friendly cultivation

It is climate-friendly to cultivate during winter. You will be cultivating other plants than you did during summer. Use nature’s energy sources such as rainwater and the sun. When it is time to harvest, you have not used any form of external heat source, no packaging is needed nor is transportation. Also make sure that when you winter cultivate that no chemicals have been used in the process.


What can be winter cultivated in the greenhouse?

I have been winter cultivating for years in Denmark. Over the years I have knowledge about which crops are resistant to frost and which plants that later can be harvested.

  • Different sorts of kale
  • Different kinds of lettuce
  • Purslane
  • Chicory
  • Broad beans
  • Garlic
  • Peas


When to harvest

Do not expects to grow large vegetables. Instead you can for instance harvest the broccoli plants when they are small. Eat the fresh and green pea shoots and the small lettuce leaves. Due to temperatures and the slow growth, the taste can be intense. The taste cannot be compared to the taste from vegetables that you buy in stores.

Sow in mid August and September

As we move towards autumn, it is time to start sowing. In Denmark the average temperature is 13,6 degrees Celsius and an average of 145,5 hours of sunshine, which can be used for cultivation. The length of the day are getting shorter with five hours since winter solstice in June in Denmark. Aim to sow slow growing plants:

Slow growing sorts can be harvested in November or December:

  • Broccoli ’Green Calabrese’ (are sown in August and harvested in November)
  • Cauliflower ‘Flora Blanca’ (are sown in August and harvested in November)
  • Cauliflower ‘Veronica’ (are sown in August and harvested in December)
  • Parsley (are sown in November to spring)
  • Kale ‘Roter Grünkohl’ and ‘Westland Winter’ (are harvested in November to spring)


Fast growing sorts

  • Bok choy (are harvest in late September)
  • Spinnach beet (are harvested in September until the end of the year)


Tips and good luck cultivating!

  • Only harvest crops from your winter cultivation when the temperature is above freezing point and when the plants are turgid
  • In general, do not worry about the frost
  • Cover your plants with a crop cover cloth at night, when there is risk of frost
  • Sow new seeds for winter cultivation every month until after the new year