What to sow, plant and harvest in your polytunnel or greenhouse in December

It’s a good time to take a break from your tunnel or greenhouse. All you need to do is harvest your salads and ventilate as much as possible. If you have spare time you can prepare the beds for the following year. It’s a good idea to let the beds settle in for a while before sowing and planting again.

Take time to reflect on the gardening year and repeat what went well and find out what has gone wrong with other crops and make improvements or changes.

Sowing in the polytunnel

Personally I think it is best not to sow anything in December and instead wait until January when the days are starting to get longer again.

Harvesting from the polytunnel

You may still harvest some:

Coriander, corn salad, dill, lettuce, oriental brassica salads, rocket, pak choi, parsley, radish, scallions, spinach and turnip.

Rocket: one of the greens you may still be able to harvest in your polytunnel or greenhouse in December

General Polytunnel maintenance

  • Hardly water at all – once a week at the most.
  • Ventilate as much as possible.
  • Clear all remaining summer crops. Don’t leave any of their crop residues in your tunnel or greenhouse otherwise their relevant pests and diseases will be carried over to the new crops.
  • Start chitting your first early potatoes indoors.
  • Continue harvesting your winter salads.
  • Prepare the soil for the early spring crops by incorporating compost or composted manure into the soil.
  • Tidy and clean the tunnel or greenhouse: wash the plastic or glass, clean and tidy away the pots and trays.

Thanks to John Harrison of Allotment & Gardens

You can get John’s book Vegetable Growing Month-by-Month here.