Garden innovations - forcing vegetables

While forcing vegetables, that is getting them to grow ahead of their normal season, is not a new process, new technologies make it much easier for us to have what used to be called 'exotic' or 'hot-house' crops, almost whenever we want them. This is important too, as people begin to worry about food miles and how far some of our basic foods like September leeks or December strawberries have travelled to reach us. Here are some of the best vegetables for forcing and suggestions on how to get them onto your table weeks before they are ready in the fields.

• Asparagus - even the Victorians enjoyed forced asparagus, and in Copenhagen in the 1800s, forcing was used to produce fresh asparagus, out of doors, on 28 January - the King's birthday. It's unusual in that it can be forced either indoors or out. To force outdoors, dig trenches either side of an established asparagus bed containing four year old plants. Make the trenches two to three feet deep and two wide and fill them with hot (unrotted) manure. Then set frames over the whole thing and use lights to add to the forcing. You need to achieve a temperature of 15 to 16 degrees Celsius so you may need to add mats over the frames for extra insulation. As soon as the asparagus shoots reach the surface the manure should be removed and this can give you asparagus in four to six weeks! Alternatively you can lift three year old crowns and force them in the greenhouse by putting them on a heating pad or bench, covering in three inches of light soil or leaf mould and keeping them at 18 degrees C.
• Carrots can be grown under glass, with the first seeds being set in November, the second crop in mid January and the third in mid February. Their bed should be of eighteen inches of manure covered with nine inches of light soil (friable soil with a high sand content) and this hot bed should be within six inches of the glass, to ensure maximum warming.
• Endive - like carrots - can be sown in January and February on a hot bed giving a temperature of around 18 degrees C covered with 6 inches of soil. The beds were covered with frames, which in turn were covered with mats to conserve heat. Prick the plants out once they have four leaves and keep in a warm bed.

Garden innovation forcing vegetables photograph by humean, used under a creative commons attribution licence