Professional market gardener Tamsin Borlase explains the mammoth 12-year crop rotation that she carries out on her plot.

The importance of a good rotation was drummed into me during my time at the Soil Association. Many a plan for organic conversion fell down due to a lack of understanding of this, the most vital principle of organic or low input production. A good long rotation full of green manures will also save you money, reducing the need for brought-in fertility, minerals and pesticides (for those of a less organic persuasion) and healthy soil will result in fewer expensive crop failures and increased yields.

Much has been written already and most decent horticultural/gardening handbooks will give you the basics but 3 main principles apply.

1. Rotation is necessary in order to maintain healthy crops and avoid the build up of  pests and diseases associated with a particular crop family.

2. Any rotation in a low imput system should include a fertility building phase to provide sufficient nutrients for future crops.

3, Rotation allows crops with differing nutrient requirements to be grown successfully as fertility reduces throughout the cycle.

In the first years I read much about rotations and in the beginning we used a model based in the RDRA  Encyclopedia of Organic Gardening, however it soon became apparent that to balance the space requirements for certain crops (brassicas and potatoes for instance take up a disproportionate amount of space in a rotation) and to ensure a really good disease break for these same crops and the Allium family, a longer rotation was preferable.

Based loosely on a standard 4 year rotation we came up with a plan that included our pigs gave us adequate variety to fill the veg boxes and our larder for the year.

Years 1 and 2

Red clover and chicory.

Clover is the engine of any organic system, taking airborne nitrogen and fixing it in small nodules in the root system. The clover is cut and mulched for the first season and then allowed to flower in year 2 for the bees. The chicory has a long root and is fantastic (in our situation) for breaking through the compacted layer. It helps mobilise minerals from the lower levels making them available for the growing plants in later years. It also has very pretty blue flowers loved by insects

Year 3

Clover and pigs.

The pigs –  either Black Berkshires or Berkshire xTamworth - arrive in March and spend the summer rooting up the clover and chicory, manuring the patch as they go. Depending on when they go “down the road”, I may put in a crop of Phacelia after they have vacated to provide ground cover for the autumn. This plant is not allowed to flower and will lock up nutrients and keep the soil stable during winter rains.

Year 4

Potatoes.

Potatoes love nitrogen and are a hungry crop and so will thrive on this rich, well fed soil. The digging needed to harvest them and the dense cover of the leaves will leave you with weed-free, friable soil with enough residual fertility for the next two crops.

Year 5

Alliums.

The onion (Allium) family follow the potatoes, starting with leeks. Leeks are a long season crop: sown in February, they will crop 9 -14 months later. Pencil-thickness plantlets are dibbed in as the first early potatoes are harvested in July. In October I will plant overwintering onion sets and garlic. In the following February I will plant the nursery bed with leeks for next years crop and some shallots and finally in March and April the summer onions sets, to be harvested in August.

Year 6

Beets, spinach and lettuce and maybe some carrots.

Spot the mistake above! Adding another plot into the rotation meant I had to do some juggling!

Beets and carrots don’t require as much nitrogen as other crops. In fact, sowing roots into newly manured land often results in forked roots. Compost is forked around the established chard plants and in the rows for spinach.

Year 7

Runner beans, peas and french beans undersown with white clover (if you don’t have a drought!).

With a long rotation such as this we need to add fertility at this point. White clover does not thrive with too much competition but once established makes a good dense cover that will smother annual weeds grown between the rows and sown into the gaps. As these crops are removed to stay a further year, they will fix nitrogen for the next section of the rotation.

I tend to manure the runner bean trenches in the autumn and spread very well-rotted compost thickly around the french beans once they are established. Although all these crops are also legumes and therefore nitrogen-fixers, they need to be regarded as neutral in terms of nitrogen balance as the crop removed will take as much as the roots will put in.

Year 8

Broad beans undersown with white clover. (Legumes)

The low-growing habit of the clover means that planting beans through the it shouldn’t be a problem and an autumn planting of beans will get away well. Half-autumn and half-spring planting should give a good spread  of harvest times.

Year 9

Solanaceae and sweetcorn.

The soil should be in good heart again by now but I tend to add a little well-rotted manure in the late summer/autumn ready for potatoes. I cover this with a black plastic to let the worms pull it all down and dig in the spring prior to planting potatoes. Rolling the ground cover to one side will prevent weeds from germinating in the area planned for later plantings of tomatoes and sweetcorn.

Year 10

Brassicas.

I lime this plot in spring as this area will take my brassicas this year.. This isn’t essential and should only be done if the pH is too low (which in my case it is) I use a dolomitic limestone which is slow releasing and more gentle to use than many of the alternatives.

I halve this plot, growing  summer and winter cabbage, purple sprouting. cauliflowers, swede and Kolrabi in one side and baby leaf salads grown in succession on the other. I sow every week all summer gives delicious leaves from March to November. The mustards and many oriental leaves are part of the brassica family.

Year 11

Cucumbers, courgettes and squash.

This hungry and thirsty family I grow in manured/composted  holes through permeable membrane. I leave it covered as much as possible to keep the weed burden down and the moisture in.

Year 12

Carrots, parsnips and soft herbs.

These come at the end of the rotation in fertility terms. I may add a little compost to the area designated for leafy herbs but the roots need no more than the residual nitrogen at this stage.  In the spring it is important to establish a false seed bed before planting carrots. The weeds suppressed by the membrane in yr 11 can pop up like mad and waiting one more week (do what I say not what I do!) and a good hoe pays dividends.

Adapting this to the kitchen garden or allotment

Obviously our set up  is considerably larger than you would find in an average garden. However, for the most part this rotation will work on a much smaller scale. In fact I use it in the school garden and for the mini version that is 5m x5m that the children share too. (It’s never to young to learn about the principles of rotation!) In a domestic situation I would take out 1 year of clover and the pigs, leaving you with 1 resting/fertility building year and maybe also remove one year of legumes, but this will depend on how many peas you want to be able to freeze for the “dark times”.

Removing the pigs, clover and one lot of beans will give you a 9 year rotation.

Even numbers being tidy, I would be inclined to round it up to 10 and add a bed of flowers between the solanaceae and the brassicas. This will provide an abundance of cut flowers (if you select the right cut and come again annuals) attract pollinating insects into the garden as well as adding a glorious splash of colour into your garden.

Clover

Potatoes

Alliums

Beets/lettuce

Beans/peas

Tomatos/sweetcorn

Flowers

Brassicas

Curcubits

Carrots/herb

This rotation gives us about the right quantities of the various crops, enough to gorge upon during their season and a sensible amount to be able to store through the winter, often eating last years squash in the following April and stringing up enough onions and garlic in the larder to last most of the winter.

Tamsin Borlase is a professional market gardener. If you live near her Henley farm, you can order local veg boxes from her. And her website is well worth a look too for inspiration about veg growing.