January usually sees the top few inches of earth frozen solid everywhere in the garden. Even stalwart crops like kale droop and look decidedly unattractive. Parsnips and brussels lurk here and there but it’s a wellies and warm coat job whenever they’re needed. Everything else is just sitting under a thick mulch, waiting. Unless, of course, you have a polytunnel...
So, what difference can a polytunnel make to your gardening in January? First and foremost, it will allow you to keep lots of crops growing right through the winter and into the warmer days of spring. And when the sun does show itself, even in the depth of winter the temperature in a polytunnel will be warmed within minutes.
Working in a polytunnel over winter on a fine day you will be quite comfortable in jeans and a T-shirt - clearing weeds, cultivating, clipping a few leaves of this and that for dinner - while outside the temperature may well have stayed below freezing all day.
For gardening junkies like me, a polytunnel means there is more to winter than huddling round a fire with seed catalogues, dreaming of spring. In your polytunnel you can be actively sowing, growing and even harvesting right through the coldest months.
There are several commercial heaters available burning either propane or paraffin, and these will keep the temperature well above freezing even in the coldest weather. However, be very careful when re-filling the paraffin - a spill on your soil will seriously damage your plants. So don’t re-fill in the tunnel, take it outside onto a path.
I also use horticultural fleece cloches over the beds. These are made by placing a series of hoops, across the beds every few feet. Then I drape the fleece over the hoops. Fleece can be easily pulled back, either to allow access to the plants or to increase the light levels for the beds on warmer days, and put back again for overnight protection. There are several weights of fleece available: mine is fairly heavy and will protect the plants beneath from upto -6ºC. When that is added to the protection already provided by a polytunnel, lots of salads and vegetables will survive all winter. And they’ll be there whenever you like.
A water butt is a great thing to have in a polytunnel - and the bigger, the better. Not only will it be handy for watering here and there but it will also retain available heat. The water will soak up the warmth when the sun comes out, then slowly release it overnight, just like a storage heater.
Broad beans, garlic/elephant garlic, peas (round-seed varieties) and turnip. Beware of mice digging up the broad beans and peas! They love ‘em. Bottle cloches (i.e. plastic bottles cut into tubes roughly 15cm long and pushed into the earth around the seeds) will protect them from rodents. Add a ring of copper tape roughly halfway up and you also have a good slug barrier. Garlic should be a reasonably safe bet and can be sown throughout the winter, and turnip seeds are able to germinate only a few degrees above freezing.
Garlic/elephant garlic, and everything else on the 'harvesting' list.
Beetroot, cabbage, carrot, cauliflower, celeriac, celery, chard, coriander, daikon, lettuce (and other salad greens), kohlrabi, mizuna, pak choi, radish, rocket, spinach, spring onion, turnip.
Please see our Top Of The Crops for a list of over 80 Vegetables, Fruits, Herbs and Spices, Flowers and Exotics.