With the help of a bit of cover, and carefully selected varieties of seeds, it is possible to grow vegetables and herbs all year round in the United Kingdom, and presumably therefore in other temperate countries that have frosty winters.
In my corner of Scotland, away from the sea and up in the hills, there is only one month of the year that can be guaranteed to be frost free and that is July. Most years we cannot grow courgettes or runner beans outside without cover. In our case, experimenting has paid off and we often have more produce in winter than in summer. Last year by the end of winter we were fed up with salad!
Why grow vegetables in winter?
There are a number of advantages to growing vegetables in winter:
- Mature overwintered veg keeps growing until December under cover, stands for the winter then comes away fast in February. They can be picked for much of the winter. There might be lean pickings in January but there is usually something – perhaps a bit of kale, land cress, claytonia, lamb's lettuce, herbs and carrots.
- Later autumn sowings will overwinter as seedlings that get going quickly again in February and are ready long before spring sowings. This eliminates the 'hungry gap' – that period of time when seeds have been sown in spring but little is ready to eat.
- Vitamins and minerals are harder to obtain in winter, especially vitamin C. Having something fresh from the garden can make a big difference.
- Fresh organic produce is more expensive in winter. Therefore winter veg saves you more money than summer veg. Rocket, radishes, salad leaves, parsley and mint are all expen-sive in winter yet easy to grow at home.
- The ground is as well growing something as sitting there empty.
Protecting plants from frost
Any protection that you can give plants over the winter will help them, although there are a number of things you can grow with no protection at all. A greenhouse or polytunnel gives the best protection and plenty of indoor space. We cover some of the plants with polypropylene floating mulch inside the tunnel or greenhouse for extra insulation.
Cold frames are another good option and a layer of floating mulch or bubble wrap can be used on top of the plants inside the frame. Simple home-made frames work fine. Do remember to remove the bubble wrap and start watering again in the spring. Floating mulch laid over the soil outside gives weather proofing on its own and can be weighed down with bricks or stones. It prevents mud from being splashed onto salad crops as well as giving frost protection and making plants grow faster.
We had great success last year with an old caravan window found in a lay-by which we put on top of some lamb's lettuce. Lamb's lettuce will grow outside all winter without protection but that which was covered was ready first, in early February. Once it was finished, the uncovered stuff took over. We had lamb's lettuce galore from February till the end of April. Don't forget that if you have a conservatory, food plants can be grown there in pots during the winter. Windowsills in the house tend to be too dark for plants that are going to be there for any length of time but work fine for salad sprouts (see later).
Starting seeds & succession sowing
Start sowing again from mid July onwards, as the ground is cleared by other crops, then continue until the weather gets too cold. That usually means until the end of August in the north or September further south. These sowings will grow at different rates. Sowing in succession actually works better at the end of the year than it does in spring, when all the sowings tend to catch up with one another. Earlier sowings will be ready from August to late September, and can be used as 'cut and come again' crops from then onwards. The more you cut them the longer they stand, so keep cutting, making sure you leave a bit of green to keep the plant alive. They will eventually stop growing but will stand over the winter, and start to grow again in February. Later sowings will be part-grown at the end of the season. They are poised to finish growing in spring and to follow on from the earlier sowings. This two stage process means you will still be harvesting right up until the spring-sown vegetables begin to mature, and you will seldom be without some garden produce.
Early seeds are late seeds
Seeds that are described as 'early' on the packet can also be sown at the end of the season for overwintering. There is the odd exception, for example parsnips. If in doubt, experiment. Conversely, anything that says it is a 'late' also usually works as an 'early'. This year we obtained some onion sets that according to the bag were for autumn sowing. They were reduced to 50p when purchased in February. Half were sown outside in March and the other half in cold frames. The cold frame ones were ready to eat by June and the others followed on a couple of weeks later.
Once it is too cold to sow in the greenhouse, move indoors and sow seed trays of peas, cabbage, broccoli and kale on a south facing windowsill. These can be cut as seedlings once they are two to three weeks old and added to salads and soup. Grow salad sprouts in the normal way too, in a salad sprouter or sieve. The quickest ones are chick peas and lentils. Red cabbage sprouts add some colour to winter salads.
What to grow in winter
Perpetual spinach, chard, parsley, rocket, lettuce and radishes can all be sown at four week intervals from July onwards for both a winter crop and some seedlings to overwinter for fast take off in spring. Chard is less hardy than perpetual spinach so if you only grow one of them, grow the spinach.
The radish 'long white icicle' does well and can be used as a vegetable as well as in salad. It will stand for a long time in winter undercover. A variety of lettuce from Thompson and Morgan called 'Freckles' is good for autumn sowing. It is hardier than most and slugs don't like it. We have kept plants going all winter under bubble wrap in a cold frame.
Land cress and lamb's lettuce are wonderful, hardy salad crops which will stand outside all winter in pretty much any weather. Leave a plant of each to go to seed and you will have a steady supply of plants at different ages and stages springing up everywhere. Lamb's lettuce is sown from July onwards but you only need to sow it a couple of times, once indoors and once outside, to get a supply for months. It is expensive to buy and you often see it in those bags of ready-washed salad. Land cress can be sown from spring until September, but will stand for months from a single sowing if picked regularly. It has a similar taste and appearance to watercress. As well as using it in salads, make a mineral-rich soup using a watercress soup recipe.
Claytonia is another easy winter salad crop, although it does need a bit of cover. If you have a polytunnel, greenhouse or cold frame it will keep going all winter, and will self seed. Slugs do not bother much with claytonia or with lamb's lettuce and land cress.
Pak choi, Chinese cabbage and other similar Chinese greens need to be sown after mid July or they will go to seed. They are best in a tunnel or cold frame. Slugs love them so keep an eye out for damage. Garlic can be planted at most times of year but July plantings work well and are ready the following July. We put single cloves back in the ground whenever we harvest some and have it dotted all around the garden, to pull as required. If none is ready, the green tops can be cut and used. Spring cabbage can be used as a cut and come again crop as well for full sized cabbages.
Carrots (stump-rooted) do well on most soil and will stand in the ground for a long time, to pull as needed. Celery is easy to grow pretty much anywhere. Sow it after mid July for winter crops, or it may to go to seed. There is no need to earth it up. We have been sowing a culinary celery seed, variety unknown, for several years with great success. It can also be sown in September and the small plants will overwinter and start growing again in the spring.
Leeks, as most gardeners will already know, are planted in spring and ready in autumn. They will stand in the ground all winter and can be eaten until the first shallots are ready in the spring. They are in many ways more useful to the winter gardener than onions, being very hardy and easy to grow. Kale can be sown as usual in midsummer for a winter crop or in September for a second, later crop. Sow kale and broccoli again under cover in early spring for some cut and come again tender leaves to add to salad. In fact, you can sow it pretty much any time and have plants at different stages of growth for a year round supply. It will stand most weather, although the variety 'Nero' with elongated, dark leaves is less hardy than the curly leaved varieties. Kale pesto, made from tender young leaves is tasty and freezes well. Just use a recipe for basil pesto.
Purple sprouting broccoli can be sown in June or July and grown over the winter for an early spring crop. The leaves can be eaten as well as the heads. Leave the old kale and broccoli plants in the ground in spring and they will continue to provide greens until well past mid-summer. If you let a couple go to seed, they will self sow and cross with each other giving some interesting variations. We had a lovely purple sprouting kale this year! We usually grow spring cabbage. It lasts in the ground most of the summer and we are still eating spring cabbage, sown last year, as I write this in August.
Most people grow too many cabbages and kale plants. 12 cabbages means one for each month of the year, which is enough for most of us. Most gardeners grow kale, cabbage and purple sprouting broccoli, but may not get the most from them. You can juice winter greens and also use them in salads; you can freeze cabbage, kale and leeks chopped up, they are then ready to use. Field beans are like smaller broad beans. They are hardier though and do better over winter. Sow them in spring and again in mid August after you lift the potatoes. To save the seed, pick a few mature pods and leave them on a windowsill to dry.
Jerusalem artichoke tubers can be planted from spring to mid-summer for a crop from November to January. When you harvest them, resow a few of the tubers in a different spot for next year. Beetroot will overwinter outside but does better undercover, so put some in a cold frame. It does not like acid soil. Parsley and rocket can be sown in September under cover. Small seedlings will stand over the winter and grow on in spring. Slugs like parsley, so use organic slug control as needed. Potatoes can be planted in pots in a greenhouse or polytunnel and will be ready in a few weeks. Just keep back some seed potatoes to sow in the autumn. Potatoes can also be planted very early in a polytunnel or frame and then transplanted back outside when the weather improves. Instead of discarding any 'rogue' potatoes that come up in the wrong place, transplant those too.
Moving vegetables indoors
When it gets colder, dig some plants up and replant them undercover. Alternatively put a cold frame or some floating mulch over them. Dig up mint roots and lay them lengthwise in a box or seed tray, covering them with compost or soil. Undercover or indoors on a windowsill, they will shoot all along their length. Partly grown spinach and chard can be moved successfully as can lettuces and other salad crops. Experiment and see what works for you. Who would have thought you could transplant potato plants, or use the celery seed off the kitchen shelf?
Janet Renouf-Miller is a fibre artist; she teaches spinning, dyeing, crochet and knitting, and runs simple living workshops. She became interested in gardening as a small child when she had her own little plot, on which she preferred to grow vegetables rather than flowers. Her blog is here.
Book: Edible Perennial Gardening: Growing Successful Polycultures in Small Spaces by Anni Kelsey
Book: No Dig Organic Home and Garden by Charles Dowding and Stephanie Hafferty
Watch: The micro smallholding
Beginner's Guide to Vegetable Gardening by Tim Graham (the Yard and Garden Guru) http://yardandgardenguru.com/vegetable-gardening-for-beginners/ is worth checking out too.