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

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Posted Sep 29 2016 by John Harrison of Allotment & Gardens
A greenhouse in October

October is the month for clearing and tidying. Your cucumbers and courgettes are likely to be finished and many other plants are getting exhausted and diseased, but hopefully you have a batch of new salad crops ready to plant out now. I always enjoy this time of year when the tunnel or greenhouse becomes completely transformed and rejuvenated again.

October greenhouse tasks

If you’ve still got crops, open the vents on fine days to avoid developing a muggy atmosphere which encourages fungal diseases. As tomatoes etc. finish, clear them out and wash any old pots etc before putting them away.

If you can, give the house a good clean with a little detergent and disinfectant and a scrubbing brush. Clean glass will allow more light through in the dark days and cleaning the frame will remove pests looking for a good spot to over-winter. Once clean you can insulate it. Bubble wrap is good or heatsheets will do the job.

Sow a hardy lettuce like Arctic King and grow in your greenhouse border to give you a salad whatever the weather.

Sowing in greenhouse or polytunnel

Direct sowing into beds

There is now plenty of space again for sowing directly into the beds. Any salad crop can be sown directly into the ground now or sown into modules for planting out later. The decision is yours.

Planting into beds

I always look forward to planting out the garlic cloves into the beds in October. If you plant them in early October they will be ready and harvested in May just in time before your tomatoes need to be planted. You can also plant overwintering onion sets.

Sowing into modules/pots (18-20°C)

The best time for your overwintering salads was really in September, but if you have missed that date you can still sow them now. They may not be ready before the end of the year but will produce well in late winter until early spring.

  • Claytonia (or Winter Purslane) – 5 seeds per cell
  • Chervil, Coriander, Dill – 5 seeds per cell each
  • Oriental brassica salads (all types) – 5 seeds per cell
  • Scallions (Ishikura Bunching) – 10 seeds per cell
  • Spinach (annual) – 4 seeds per cell

Harvesting

In October the summer crops are fizzling out and their quality declines. You may still harvest some:

Aubergines, basil, calabrese, coriander, Chinese cabbage, courgette, cucumber, dill, Florence fennel, French beans, lettuce, melons, oriental brassica salads, pak choi, parsley, peppers, salads, scallions, spinach and tomatoes.

General tasks

  • 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.
  • Clean your tools and rub boiled linseed oil onto the handles and a mixture of old oil and diesel to get rid of rust on metal blades.
  • Order your seeds, seed potatoes, onion sets and garlic bulbs.

 

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