Spring Cottage: crop rotations - Telegraph By January I can definitely feel the sap rising and I am keen to sort out the seeds by ditching all the out-of-date ones and filing away the newly ordered packets. Unfortunately, this exciting and pleasurable task is always marred by a long discussion with the Best Beloved about rotation - the art of moving vegetables around to avoid soil-borne diseases and pests. It's amazing how two people gardening on the same plot can have entirely different recollections about what grew where. We have learnt, over many years, to have a piece of paper each and to smile sweetly through the lengthy procedure, while inwardly grinding our teeth. If you're organic, like us, a rotation plan is a vital calculation because, should your carrot foliage suddenly acquire a purple tint at the tips (an indicator that carrot root fly is active), you cannot apply an insecticide. If you pull out the offending carrot (and it normally starts with one) your fly problem will move along the row much faster, as if by magic, so you are stuck with it. Should it take hold, the roots will be marred by black horizontal banding and then cream grubs will wriggle free. Worse still, the sweet roots will acquire an unpleasant flavour designed to put off pests (and any other creature bent on munching the roots). That includes you. At Spring Cottage we try to follow a logical four-year rotation plan with each group of crops taking up a similarly sized space. Our four groups are potatoes, legumes, brassicas and roots, along with onions, in that order. Potatoes come first in the table, moving down year to year, and we grow all of our own. The blight-resistant maincrop 'Cara" does well on the allotment if lifted before the end of September. First and second earlies, including 'Lady Christl" and 'Foremost," are harvested before the muggy blight-prone month of August and some of these "earlies" are grown in the garden. We also enjoy 'Harlequin," 'Belle de Fontenay" and 'Victoria." Legumes come next in the plan and my prized varieties are the pea 'Hurst Greenshaft," broad bean 'Jubilee Hysor," climbing French bean 'Blauhilde" and the dwarf French bean 'Stanley." Runner beans include the fleshy, stringless red-flowered 'Polestar" and 'White Lady," which is a really tasty bean. I am also devoted to the recent hybrid, 'Moonlight," which has French bean and runner bean blood. It will crop well in hot temperatures, unlike runner beans, which have a tendency to drop their flowers. The nodular roots of all legumes provide extra nitrogen for the soil, helping the growth of hungry brassicas, so they normally follow beans in all rotation plans. Onions and roots are the fourth crop. Manure is added after these, but before potatoes, because root crops dislike freshly manured ground. The roots fang and divide. This simple system soon becomes complicated. Certain vegetables (sweetcorn, Witloof chicory, courgettes and squashes) don't fit into any of the four categories but must be added in somewhere. We must find room for our favourite winter squash 'Sunshine" (from Thompson & Morgan) because the chestnut flavour is outstanding and the small round orange fruits are perfectly proportioned for a couple of meals. Normally our squashes ramble over our allotment. Then there are the immovable feasts like strawberries, which should never be close to potatoes because both can suffer from verticillium wilt, a fungal disease. Some roots, like turnips and swedes, are brassicas and prone to the same pests and diseases, so they are put into that group. Lime is often recommended: I don't apply it. Adding lime to Cotswold soil would be the gardening equivalent of taking coal to Newcastle. The trouble is I throw a spanner into the works every July by planting up gaps with anything I fancy at the time, using up as many open packets as I can find. I call this my late-summer lottery because it's the nearest this sensible Yorkshire grandmother gets to gambling. It paid off brilliantly last year due to a clement autumn and a mild winter, despite the fact that August was too dry for germination. Dwarf French beans cropped into late November, protected from frost in the lea of the greenhouse. Carrots (which do have some fly) and the F1 beetroot 'Alto" are still being dug up and eaten. My preferred late-sown carrot is 'Amsterdam Forcing 3," a fast-maturing AGM variety normally recommended for early sowing. Autumn and winter varieties are too slow to mature from July sowings and I've discovered that the hard way. Our most productive areas are our double dug 8ft x 4ft beds. No guesses for who does the double digging: it's the rufty tufty male half of the partnership. These beds please him greatly, as they yield our target pound of produce per square foot. Everything is weighed and recorded - unless I can get to it first, of course. We have a strip of seven and a block of seven beds. They are double dug individually at the rate of three or four a year. This uses up most of our garden compost, so it's important to be careful about what's added to the heap. Diseased leaves and infested plants go in the green bin. Crop rotation began with the medieval strip system and Spring Cottage sits amid an ancient group of fields. Any illusions of grandeur I may have had were shattered by the 18th-century map of Cold Aston. Our cottage is clearly shown, labelled "the hovel in the waste." Such is life! Once the rotation plan is on the kitchen wall the Best Beloved treats it like scripture and regularly cites Ockham's razor. This principle, attributed to the 14th-century logician and Franciscan friar William of Ockham, concludes that when you have two competing theories that make exactly the same predictions, the simpler one is always better. And so it is with rotation plans - the simplest is best.