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A GUIDE TO CROP ROTATION
From the smallest vegetable garden to the largest allotment, crop rotation is essential to growing healthy crops and avoiding some rather nasty pests and diseases.
If the same vegetables are grown on the same plot of land for more than a season or two, pests and diseases which feed or depend on them will quickly multiply and cause significant problems. Not only that, some soil nutrients will become lacking causing the crops to grow badly. Our four year rotation plan is easy to understand and implement in your garden / allotment.
An easy to manage crop rotation plan can be based on a four year cycle which will be sufficient to prevent the build up of problems. Your first action to create a crop rotation plan should be to create a list of the vegetables which you want to grow on your land. This is essential because although we do not normally grow tomatoes on our plot (we grow our tomatoes in grow bags), you may want to grow lots of them. On the other hand, we like lots of onions and garlic which may not suit you. Every gardener is different as far as the crops they prefer is concerned.
We provide a useful, automated tool to generate a four year crop rotation plan for you, it's free and can be found here. Before you go there however, a word or two about how it works. On the first page you click the vegetables which you want to grow and then click the box to confirm your selection. This will take you to a page which does two key things. First it generates a personalised calendar for those vegetables and at the bottom of the page it will generate a four year crop rotation plan - that's the bit you are interested in.
You will notice that the rotation plan has four plots plus another one entitled "anywhere / permanent". You need to stick to grouping your vegetables as defined in plots 1 to 4 but the ones under the "anywhere / permanent" group can be planted in any of the four plots. This is useful because if you have a shortage of vegetables which fit into one plot, this can be evened out by including several of the "anywhere / permanent" group in the plot.
So, with the help of our crop rotation tool you will now have a very good idea of where to plant your vegetables this year, we'll call that year 1 for convenience. In year 2 though, you need to rotate the crops so that they are grown in different plots. There are good methods and bad methods for doing that, a well accepted method to rotate your crops is shown in the picture below.
Vegetables which can be planted anywhere in the rotation plan are sweetcorn, lettuce, courgettes, cucumbers, pumpkins, squash, radish and rhubarb although it does pay to move around each year. If the above rotation plan is unbalanced because of the range of the vegetables you want to grow, French Beans and Runner Beans can also be swapped to other groups without any ill effects.
Runner Beans are included in the above crop rotation plan however our personal experience (and from the experiences of others) is that they can be grown in the same place year after year without any ill effects. Many gardeners have permanent supports for runner beans and this works fine.
To keep it all simple and clear we have named the individual vegetables in the picture above. Some books and websites refer to groups of vegetables rather than individual ones. The names used are legumes (peas, beans etc), brassicas (cabbages, greens etc), potatoes (includes tomatoes) and finally onions / roots.
Each year it is a good idea to test the pH of your soil in all four beds. pH is a measure of the acidity / alkalinity of your soil with a reading of 1 being the most acidic and 14 being the most alkaline. Most vegetable prefer a neutral pH which is about 6.5 to 7. Kits to test soil pH are available to buy online and also at garden centres and many diy stores.
If your soil is too alkaline (i.e. the pH level is too high) you need to add compost and manure to decrease the pH level.
If your soil is too acidic (i.e. the pH level is too low) you need to add lime (available at garden centres) to increase the pH level. When adding lime to soil read the pack instructions carefully to get the dosage correct.
Different vegetables have mild preferences for particular soil types as far as pH is concerned. However, unless you are expert at adjusting soil pH, simply aim for a level of 6.5 to 7. After several years of growing vegetables on an initially neutral soil, in all probability it will become slightly acidic and need a small dose of lime.
COMMENTS / QUESTIONS LEFT BY OUR READERS
|Date: 12 March||From: Jenny T|
|You have put potatoes and tomatoes in the same plot yet I have read in several places that they should not be grown together because tomatoes attract potato blight.
ANSWER: Potatoes and tomatoes should be in the same rotation plot. I would be very interested if you could identify a crop rotation plan which does otherwise.
You are correct that both potatoes and tomatoes attract blight. Blight, which travels by wind and water, spreads over long distances and if it occurs in one part of your garden it will spread to all parts so there is no point in separating the two plants. Indeed, on large allotment areas it will spread from one allotment to another in a matter of hours. If blight is present it will spread to all susceptible plants in a surprisingly large area. Let's hope we have a good 2016 as far as blight is concerned.
|Date: 3 October 2015||From: Bill|
|I just taken allotment on, I don't know what previous tenant had planted in beds, should I just prepare to correct ph levels in each bed?
ANSWER: You have little alternatives I think. Tomatoes and potatoes are two common vegetables which cause a build up of pests and diseases. You could try placing large bottomless pots where you want the plants to grow and fill with multi-purpose. Then plant the tomatoes and potatoes in the multi-purpose. This would provide a degree of protection (see here for how I plant tomatoes in normal circumstances, not to avoid the problem you have, but just because it works well).
|Date: 25 January 2015||From: Mike Hamilton|
|Just what I have been looking for and a real help.|
|Date: 01 September 14||From: Carmen|
|I'm quite new to gardening but find much joy and reward in doing it. My garden is not very big, so I try to mix growing in soil with container gardening as well as growing tomatoes in a cold frame. I found your site very useful and the 'custom made' vegetable calendar helped a lot. I try to do be as close to organic gardening as I can, not using any chemicals and pesticides at all.
I would really need your advice regarding the soil from potatoes. I started growing potatoes in big bags last year and was pleased with the results so have done it again this year. As I read, believe and use crop rotation, I had used the soil from the potatoes bags to re-pot some of my flowers and filled in few 'gaps' in a little flower bed. I also have a raised bed in which grow 1) legumes (beans and peas) 2) onions and garlic, 3) beetroots, carrots 4) turnips, radishes and few broccolis. I also have 3 courgette plants and different salads leaves inter-planted.
Could you please, suggest how I could use the soil from the potatoes bags and the tomatoes pots from the greenhouse? Can I divide it between the raised beds? I know that tomatoes and potatoes are the same family so cannot swap them around. I cannot buy new soil every year so I try to combine and rotate it around the garden and the containers, but I'm a bit confused now with the compatibility and the crop follow on rules.
ANSWER: I'm not surprised you are confused Carmen, the terminology used by some books and websites regarding crop rotation is out-dated and not clear. For that reason our crop rotation plan above uses the real name of individual vegetables not groups such curcubit (what on earth is a curcubit!), legumes and brassicas - and the RHS site is as guilty as the others.
If your compost has been used to grow potatoes, my advice is not to re-use on beds where potatoes, tomatoes, peppers or aubergines will be grown next year. It can be spread over the ground /raised beds where you plan to grow any other crop. That's what I do and it's worked well for the last 30 years or so. So for the crops you suggest, beans, peas, onions, garlic, beetroot, garlic, turnips, radish and broccoli the compost can be safely re-used as and when you want.