Rotate or just move stuff around

We almost all attempt to practice some sort of rotation though I suspect in practice expediency often messes up our plans. Many different examples are given in textbooks but unfortunately they are little use as guidance and can rarely be fitted to any gardener's particular needs. Individual tastes vary and few of us want exactly the same combination and quantities as are proffered in most textbook rotations. This is the main problem; these worked examples require you to sow, grow and then use the same vegetables in the same proportions as the originator. (Who was probably on a different soil with a different climate!)

Many texts are too vague to be useful as to how we are to construct our own personalised rotation for our mix of crops. Perhaps we need go back and see where it all started and what exactly is the ideal rotation? The original idea is that by having different crops in succession in the same soil instead of more of the same we reduce the build up of pest and disease infestations and secondly that changing crops makes varying demands on the soil's fertility.

During Classical times they started to practice a form of pragmatic rotation by default. This was more along the lines of understanding what could still succeed when the soil had become 'worked out' by too many corn crops. Certain plants such as lupins and beans were seen more as tough survivors rather than as ways of restoring fertility. Attention turned to rotation as such during the late 1700s when it starts to appear in both farming and gardening literature.

Here in Norfolk variations of the four course rotation of wheat, turnips, barley then clover and ryegrass in place of the old fallow were developed. From this very agricultural background the concept of rotation came into gardening along with growing in rows and green manures. The gardener was soon encouraged to adopt a three or four year rotation of potatoes, roots then brassicas, or potatoes, legumes, brassicas then roots.

From this advice to the poor labourer on how to grow sufficient to feed his family on soup year round we got our worked examples from so many dated books. These usually have a quarter of the plot devoted to maincrop potatoes, a quarter to peas and beans, another to cabbages and the last to beetroots, parsnips and carrots. Onions and leeks were often suggested as alternatives to mix in with the peas and beans (these do not really get on in companion planting terms) and little reference was usually made to squashes, sweet corn, tomatoes or salad crops!

Apart from the already mentioned difficulty of the reader having different tastes and needing variable quantities from the expert there are two other and far more serious criticisms to be made of this conventional four course straitjacket.

Although the principle idea of not having the same crop plant on the same spot of land two seasons running and making that time interval as great as possible is valid this can also be counter-productive if the four years four quarters type plan is adopted. i.e. Putting all the brassicas or all the Alliums or all the Roots together in their own patch effectively concentrates them into a monocrop target more prone to it's pests and diseases spreading wildly from plant to plant than would be if those same plants were dispersed over the whole four plots.

Secondly it is often claimed that deep rooters such as roots are put together and shallow rooters such as alliums are likewise grouped with others thus making it easier to treat each group according to it's needs. Again a valid argument but also it is then the case that each crop within it's group is up against more crops competing in the very same niche and perhaps they could be less ruthlessly challenged if dispersed amongst other plants with differing habits.

Although there are reasons for any specific succession there are also arguments against. Most postulated rotations are nothing other than, allegedly, working examples. In fact we are dealing with expediency and mostly to make it easier to arrange the crop's planning and maintenance. There is no need to follow them rigidly except for convenience. I have long experimented with many ways of organising plots (You may wish to look again at my articles on rows and records in Kitchen Garden December 2000 and raised bed methods Sept.2001).

It does not matter much whether you use rows, blocks or whatever as long as you can identify the same positions every year and keep notes. Record keeping is essential, simply of what grew where when. After that it ought to be relatively easy to ensure that the same plant does not return to the same spot the next year and as for as long as possible. You can do no more. People often ask questions such as "I cover more than half my whole plot with my favourite xxxx, how can I rotate?" Well you can't can you? But at least do what you can and swap sides each year with the bulk, and you could also put late sorts where earlies were, and maybe change varieties. Otherwise in such a case all you can do is practice scrupulous hygiene and apply lots of compost.

However even when you try and work a rotation it is still difficult to stop conflicts appearing. In practice the right spot may not be available at the right time whereas another, wrong, spot may become free of a crop and usable. And when you wish to plant companion crops then the rotation becomes more complex still. So in practice it has to be recognised that some crops, usually the most commonly grown ones, require more attention to rotation than others. (These will of course vary with soil and climate.) Once the difficult crops are placed other crops can then be fitted in with less regard -especially easily if these are in small proportion.

By my reckoning potatoes must be rotated the most of all crops as they are so prone to so many soil borne problems. From a practical and no dig point of view they are more work and less productive if they follow a crop that leaves the ground hard such as onions, peas, beans, squashes or sweet corn and ideally they would follow real roots such as carrots as these have broken up the soil for them. Potatoes may benefit from the nitrogen left by a legume but really come too long after. They are said to be bad following brassicas if you limed those heavily as that can give the spuds unsightly skin problems -but does not affect their yield. Do not put potatoes physically near tomatoes even though they are the same family just because they cross infect their blight -and by comparison you can almost forget about any soil rotational problems between these two!

Brassicas are said to be the most important to rotate because of the risk of building up club root. But they are also very prone to incoming pests and putting them all together is crazy unless they're safe under a fleece. I find the further apart you can keep individual brassicas the better as they are much cleaner interspersed with other crops such as French beans than when grown en masse. They should never follow themselves because of club root -but if you don't have it at all then is the occasional second year a problem; I find not. Anyway when a brassica returns to the same spot after an interval I change the sort e.g. from a cauliflower to a sprout and then to cabbage. I always lime before I plant brassicas and most seem happy with the hard ground following onions, the legumes, squashes and sweet corn -and autumn planted brassicas can really enjoy any nitrogen left by the legumes. Brassicas can follow potatoes as any volunteers are not too disruptive.

Onions were once grown every year on the same bed or simply fitted into the rotation for convenience. Since the prevalence of white rot and rust it is now important to rotate them and definitely not to grow all the different alliums together but to keep them separated in different parts. Onions and the other alliums save leeks can follow almost any crops other than spuds. They prefer following crops that leave the ground hard as onions and shallots may bloat and get thick necks on loose soils. Not only is the soil too loose but volunteers are a problem if alliums follow potatoes.

Carrot root fly is such a problem most of us must grow this crop under a fleece and so it makes sense to put other prone roots such as parsnips with them or alternatively to put these really far away and not nearby in the same area. The fly emerges from the soil where it pupates so carrots must not follow carrots the next year -but it ought not be a problem the one after if you are desperate for the space. I find most true roots do not need a dug soil and do well in undug soils hard from previous crops if they are carefully sown. they do not follow potatoes well, and any volunteers add more problems. Dug soil with clods is just as bad as mixed in manure for making them fork and so I scratch a drill or station, water well and sow, the roots go straighter down into firm soil than loose! I do not put beet or turnips with roots, they need moister richer soil so it is daft to grow these in the same bed as carrots and parsnips.

Like the beets and turnips, the salad crops, leeks, celery and celeriac all like rich moist conditions. These deserve trench cultivation in such as my dry sandy soil and need copious watering most years. they can be rotated together as a group. They are all most conveniently fitted in where other more problem prone crops allow. This is easy as they can all be sown in modules for planting out as space is made available.

Sweet corn get on well with most of the squash family and like much the same conditions as the last bunch. This odd couple will swamp almost all other crops as they are thugs by nature. They are the best crops to follow potatoes as any volunteers are not very disruptive of either of them and they enjoy the broken soil. They do especially well if you mulched the potatoes with grass clippings instead of earthing up. You can add runner or climbing French beans to corn and squash for an extra crop.

Legumes allegedly do well in poorish soils as they fix their own nitrogen, they also like lime so are often dosed with it when grown before brassicas. They can follow almost any other crop and can be alternated amongst themselves in different years. I also use them as green manures trashing them before their seed is set as this suppresses wireworm numbers making them extra useful before potatoes. Legumes can be mixed with most crops that they don't shade out too much but do not go well with alliums as legumes need moister soil when the alliums are ripening and their surplus nitrogen comes too late to help the alliums, indeed it can make them soft.

So don't worry if you can't follow a 'proper' rotation; especially not the four quarters varieties. Indeed don't put them all into four blocks! Just make sure you move everything each year to a different part of the patch and make the intervals for your most problem prone crops as long as possible. Maybe a bit more working it all out with a pencil first will help....