The usual crop rotation cycle is three-years - in other words you only have a certain vegetable type in the same spot every third year - but if you want to grow potatoes itís best to have a four-year rotation.
You need to remember a simple naming process of BRL.
B - stands for brassicas (cabbage, cauliflower, calabrese, broccoli, Brussel sprouts, kale, kohl rabi, swedes and turnips).
R stand for roots (beetroots, carrots and parsnips).
L stands for legumes (peas, mangetout, and French, broad and runner beans and many green manure crops such as lupins and vetches (see catch crops later for an explanation).
Alliums (leeks, garlic, shallots, onions, chives) and salad crops should be included with the legumes.
So in plot one, you would plant brassicas in the first year, roots in the second and legumes in the third;
In your second plot, you could have roots the first year, legumes the second and brassicas in year three;
And in your third plot, legumes followed by brassicas then roots.
Potatoes need high nitrogen so can be grown after the legumes. Unfortunately, you canít grow brassicas and potatoes in the same bed at the same time, brassicas need lime and this causes scab (a skin condition) in potatoes.
Marrows, cucumbers, lettuce and sweetcorn can be grown with any of the rotation groups.