Place seed potatoes on a tray to chit in a frost free place with plenty of light. Cover the proposed growing site with 5 inches of mulch and cover the mulch with black polythene sheeting, firmly anchoring the edges into the soil. Ideally this should be done at least one month before planting the sprouted tubers – the sprouts should be at least 2 inches long. cut 9 – 10 inch slits in the black polythene sheeting at each planting site; reach in and move the mulch to one side and scrape a groove to sit the potato one half of its depth in the soil. Draw the mulch back over the potato. Repeat for each tuber. Don’t plant too many potatoes this way, about 6 tubers are enough to supply the needs of most people for about 2 weeks, before the normal first earlies are ready.
Collect some thin flexible twigs and push the thicker ends through the black polythene sheet. These are to provide support for a clear polythene sheet to form a large cloche which will provide the hot-house conditions needed for rapid growth. Place weights (timber, old bricks or the like) on the edges of the clear sheeting. Shoots are soon pushing through the slits in the black polythene. Remove the sheeting when all fear of night frosts has passed.
Progress of tuber growth can be checked by lifting a corner of the black sheeting. Those large enough may be picked off, leaving smaller potatoes to grow on. By the time the last really early first earlies are picked, the more normally grown first early potatoes should be ready to lift.
(Reproduced with the permission of B O G Birmingham Organic Gardeners)