Seeds absolutely cannot tolerate heat!
There is absolutely no need to have an empty vegetable garden in winter because there are some really good, specifically cold hardy veggies you can plant.
Do bear in mind though that plants grow more slowly in winter and putting a thick layer of straw or mulch around the plants will keep the soil warm and protect the plants, to some extent, from frost. On all our seed packets you will find a germination temperature. Every seed has an optimum germination temperature within which it will germinate very quickly. If you plant them outside of this range they will either rot (from the cold) or shrivel up from the heat. Check the soil temperature at night with any kind of thermometer pushed about 20cm into the ground. If the temperature is too cold then start your seeds indoors in trays and transplant them.
Work some good compost into the soil. Peas and beans especially are very hungry plants and need good food. If you happen to have a baby or rabbits you can add this 'manure' water straight to the plants as it will not burn them. Nappy water works absolute wonders on peas.
Things you can plant until May are:
- Broad Beans (you can eat the leaves of these too)
- Green beans (until the end of April, else start some in trays and transplant before end May)
- All cabbage varieties e.g. broccoli, cauliflower, kale, kohlrabi
- Swiss chard (try steaming the thick stems with a white sauce - Delish!)
- English spinach e.g. Viroflay only does well in winter anyway
- Carrots e.g. Kuroda does best in winter (plant before end April)
- Onions e.g. spring onions, red or white. It is already a bit late for brown onions but try them if you like.
- Italian Kale (this is not a cabbage variety and can be used as salad, stir fried or made into chips)
- Some lettuce e.g. All year butter and cos
- Radishes e.g. Japanese daikon