If you want to create raised beds then mark out the length of your ground approximately every 1.5 metres. You should make beds about a metre wide with a half-metre gap between each bed.
Pile the soil from the gaps between each bed onto one side to create a mound. You should use a line to mark the length of the bed on one side and create a vertical edge which can be shored up with treated timber. I use ten inch by one inch thick rough-cut timber. As my ground is sloping I put an additional five-inch board on the bottom side of the bed to help make it roughly level.
DIY raised beds made thus are still quite costly unless you can use recycled or gash timber and you need a lot for the average allotment. But once made – and you can do it at your leisure over several seasons – you will not need to replace the wood for many years. Each time I clear a bed of a crop I rebuild it. Because the board is damper on the soil side than the gap side it will curve out. It is a good idea, therefore, to turn the boards around both to extend life and keep them straight!
Ground that you want for root crops such as turnips, radish, carrot, beetroot, parsnip, spinach, peas and as a seed bed for brassicas and other crops for transplanting needs to be thoroughly weeded after digging. So, dig with a fork, not a spade, loosening the weeds from the soil and get the ground as weed free as you can.
If you are preparing ground in the autumn for growing the following spring cover it with a thick layer of compost and manure before covering with black poly or an alternative mulch like old carpet or cardboard. In the spring you will find the worms have incorporated most of the muck into the soil and weeds will have been suppressed. All you need to do is turn the soil and use as desired.