Crop rotation is a very important part of growing healthy plants and vegetables in your allotment or even in your back garden. But why is this so important. There are two main reasons for this, the first being that by rotating your crops it reduces the probability of soil born diseases and pests affecting your crops every year. The pests and diseases often target certain crops and if they are allowed to seize onto these crops every year they will become more of a problem and will become stronger attacking your crops with a vengeance! If the pests or diseases have no contact with their favoured crops then they will reduce drastically over the rotation period and some will disappear completely so that when you plant out the crops after the rotation they will not be attacked by these nasties.
The second main reason for crop rotation is that certain groups of crops will remove various nutrients from the soil and indeed require certain nutrients to grow healthily, these nutrients need to be replaced in the soil before the crops are replanted in that bed.
Certain crops will also provide ground cover thus cleaning the soil of weed seeds, this makes the life of the allotment holder a lot easier, less time spent weeding allows more time for care of the crops. There are certain crops that are used as gap fillers and will often not be included in the rotation, crops such as sweetcorn, tomatoes (if planted outside) and many salad plants fall into this category.
Your rotation should be planned before actually planting out your crops and it pays to draw out a plan with pen and paper so that you have a reference to look at when you do actually commence planting. The plan can be scaled down from the measurements of your beds thus giving you the chance to see how many crops you can plant in each bed.
Your crops can be divided into five main headers and they are as follows:-
The brassica family include crops such as cabbage, brussel sprouts, kale, swede and turnips. This is not always black and white as many people will add the swede and turnip to their root crop beds to allow for more space for the green brassica to be planted into.
Potatoes actually belong to the deadly nightshade family and this also includes the tomato plants, most allotment holders will grow their tomatoes in greenhouses or polytunnels or plant them outside separate to the potatoes, this allows more room for the potatoes to be grown in.
Root crops are quite self explanatory, they are crops where the root is eaten rather than the foliage. These include beetroot, carrots, parsnips and celery. As mentioned above swede and turnips are often planted with these keeping all the root crops together.
Alliums include onions and will also include garlic, leeks and shallots.
It is generally accepted that 3 year or four rotation is acceptable according to the space that you have to grow your crops. In my case I have a large enough allotment to allow me to have for main beds plus two smaller beds for what I call oddity crops i.e crops that do not come under the general headings such as squash, sunflowers etc.
My four main beds were dug to the same dimensions, each being 12 feet wide and 20 feet in length, this gives me the advantage of knowing that I can plant out the same amount of crops whichever bed they are planted in.
So my 2016 plan for the beds were as follows:-
- Bed 1- Potatoes
- Bed 2- Alliums and root crops
- Bed 3- Legumes
- Bed 4- Brassicas
Bed 1 Potatoes
This size of bed allowed me to plant 8 rows of potatoes which were 3 rows of Internation kidney- second earlies, 3 rows of Sarpo mira- maincrop and 2 rows of Maris piper- maincrop. This filled the bed nicely and all seed potatoes planted at the correct planting distance.
Bed 2 Alliums and root crops
In this bed there were 3 rows of onions planted, followed by 2 rows of carrots, swede, turnips, beetroot and later in the year 3 rows of leeks. As mentioned the swedes and turnips were used in this bed rather than use valuable space in the brassica bed.
Bed 3 Legumes
I did find with this bed that I had some spare space so also planted out my block of sweetcorn plants and 7 outdoor tomato plants. The legumes that were planted were 2 rows of broad beans, 2 rows of peas, 2 rows of dwarf french beans and 3 wigwams of runner beans ( 12 plants in total). Using up all space is essential to get the most from the beds hence the sweetcorn and tomatoes.
Bed 4- Brassica
As mentioned the brassica bed tends to fill up very quickly. The bed was prepared by adding lime to the soil, this reduces the probability of clubroot in the bed which can be a major problem with brassica. In this bed I managed to plant out 3 rows of cabbages, 2 rows of brussel sprouts, 1 row of kale, 1 row of broccoli, 1 row of cauliflower and a few swiss chard plants.
So once my 2016 planting out was completed the rotation for the following years became much easier to work out, basically the crops move back a bed over the next years until they finally return to their original beds. Thus the future planting will be as follows:-
Bed 1- Alliums and root crops
Bed 2- Legumes
Bed 3- Brassica
Bed 4- Potatoes
Bed 1- Legumes
Bed 2- Brassica
Bed 3- Potatoes
Bed 4 Alliums and root crops
Bed 1- Brassica
Bed 3- Alliums and root crops
Bed 4- Legumes
That will then complete the 4 year rotation as the potatoes in 2020 will reappear in Bed 1 as will all the other crops being planted in their original beds. This method keeps everything simple for me and hopefully it makes perfect sense to yourselves.
Following the rotation should ensure healthier crops and allow you to keep the soil rejuvenated for the next year’s planting!