Crop rotations: the basics for urban growers

My kitchen garden and forest garden border now. The raised beds currently have garlic,

broad beans and corn salad. Now it's warming up, I can start more seed sowing

and really get the season going.

 
When I published my post on my crop rotation plans for this year in January, I got a lot of interest, particularly from people on Mastodon, who asked me a number of questions. So I thought I'd write a post covering the basics as my contribution to Solarpunk Action Week. The focus is on urban growers, as that's from where my experience comes.

Why rotate your crops?
Or, do you have to rotate your crops, even in a small garden? Yes, yes, you do.

The key principle of crop rotation is that you rotate plants of the same botanical family, which are prone to the same soil-living pests and diseases, and should not be grown in the same spot every year. The aim is to prevent the build-up of soil borne problems, such as club root, white rot, and eelworms, which often have no means of control (1).

If you continue to grow the same few crops in your garden or allotment, you risk a build up of diseases in the soil that might take years to get back under control. Particular diseases include potato cyst eelworms which affects potatoes and tomatoes, and club root which affects brassicas. Of course, in smaller gardens, disease can spread to other soil areas. Best practice is to do what you can to reduce the chance of this happening.

The other key reasons to rotation your crops is for nutrient availability/soil fertility. Vegetables have different nutrient requirements, so moving them around the growing area helps to avoid nutrient depletion in the soil (and remember, you'll be adding compost and manure/green manure each year to also improve soil fertility). Furthermore, rotating crops with alternating deep- and shallow-rooting vegetables, improves soil structure.(2)

A wooden raised bed sitting on top of acid soil.

The raised bed is filled with compost, giving it an alkaline-neutral pH. 

Does soil type (pH) matter?
The pH in soil matters because crop rotations are needed for annual vegetables, which won't grow in acid soil. A pH of 7.0 is considered neutral. An acid soil has a pH value below 7.0 and above 7.0 the soil is alkaline.

When it comes to perennial vegetables, few will have much of a problem with a slightly acid soil (pH 6-7) and some will be ok in pH 5-6. Below pH 5, you can only grow acid loving fruit and vegetables, such as most fruit, including blueberries and strawberries, or acid tolerating perennials such as sorrel.

If you have heavy acid soil (pH 5 and below), as I do, then building raised beds is the way to get around this to grow annual vegetables. My raised beds are 40cms high or more, allowing me enough depth to grow any type of annual vegetable.

Basic crop rotations
Crop rotations are usually practiced on a 3- or 4-year plan. If you have the space, plant your crops on a 4-year plan. For smaller spaces, go for a 3-year plan as a minimum.

For a simple 3-year crop rotation, divide your space into 3 sections or beds, then plant:

1. Root crops (including potatoes, carrots, beetroot, garlic, onions and parsnips). You could include tomatoes in this group to keep the solanum family (potatoes and tomatoes), together.
2. Brassicas (including cauliflower, broccoli, kale, radish, kohl rabi and cabbage).
3. Legumes (peas, broad beans and beans). You could add the cucubits (pumpkin and squash) and vegetables that don't really have a group, such as corn and lettuce, here.

For a simple 4 year rotation, you would use the above, but separate out potatoes and tomatoes into their own group.

The garlic grew in this raised bed last year. This year I have created sections within this, and it

will contain a mix of broad beans, climbing French beans, squash and courgette, parsnip and beetroot.

However, even a basic crop rotation doesn't stay quite this simple, because plants have different seasons in which they grow. You plant garlic and broad beans in autumn and they'll be in their spaces from November to the following July-August. For example, one bed might have the following 4 year rotation:

Year 1: Broad beans Spring and Summer, then winter salads and green manures in Autumn and Winter.
Year 2: Peas, courgette and squash (the peas grow up, the courgette and squash underneath) for Spring, Summer and into mid-Autumn. Then plant garlic from mid-October, which will be  that will be there from October to the following July.
Year 3: Garlic up until mid-Summer, then salads and green manures for Autumn and Winter.
Year 4: Potatoes from Spring until Autumn.

After year 4, you return to year 1 and start again.

This photo shows an overview of a previous garden in mid-summer, 2015, which ran on a 4-year schedule. You can see how much you can fit into a small urban garden. The raised beds have been divided into roughly a metre squared sections, with different annual vegetables growing in each. The same view looked different next year as the crops are rotated.

Below are the plans I have, using a 3-year crop rotation cycle. Visit my post on crop rotations for my garden to see more detail.

Detailed crop rotations
Here's an example of crop rotations for a larger amount of beds, from a previous garden. This also includes a larger amount of crops, including brassicas and solanums. The beds were a mix of 3 smaller beds (1-3), and two long beds (4-8 and 9-13). The long beds were broken up into sections in order to make it easier to plan for crop rotations. This meant I could go with a 4 year rotation plan.

This is another photo from 2015, more clearly showing the different vegetables growing in different sections. In this space is: garlic, potatoes, climbing French beans, broad beans, parsnips, and carrots under white netting.

Final thoughts
You don't even need to start of with making big crop rotation plans as I do (I'm a bit of a nerd in that area). As long as you keep a record of what you plant, and where, each year, you'll be fine. Crop rotations can be flexible, just keep botanical families together. You can mix botanical families, but move them around the beds/rotations, together.

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My thanks to Alison from Backyard Larder for information regarding growing perennials in acid soil.

References
1. Growing fruit and vegetables on a bed system the organic way, Pauline Pears, 2004, p25.
2.  Encyclopedia of Organic Gardening, editor Pauline Pears, 2001, p301.

Planning the crop rotations for the kitchen garden

The raised beds that form the kitchen garden.

The new growing season is fast approaching. As of this year I have my full complement of raised beds for growing edibles in, so I thought I better work out a crop rotation plan.

This is the layout, where I have numbered each section or bed, to make it easy to plan in order to know what crop is where.

As I have a smaller garden, I've decided to go for a 3 year rotation plan instead of a 4 year plan. I'll be going into detail about this in a future post(1). Here are my 3 year rotation plans.(2)

For my garlic, the plan is to only grow a larger number which I can then share, every 3 years. I may also grow some extra food in pots as well, depending on energy levels etc.

I have allowed for sowing green manure at different points in the year, and I'll continue to add some well-rotted manure and compost to the beds, as needed.

I'm not growing anything from the Solanum family (potatoes and tomatoes), and the only thing from the Brassica family (i.e. cabbages, cauliflower, broccoli) will be Kohl Rabi. In general, the Solanum and Brassica families require a lot more work than I have the spoons to manage. I've grown Kohl Rabi in the past and found it wasn't overly impacted by the white cabbage moth, so hoping that will continue, given they aren't easily available in the shops.

The asparagus, being a perennial, isn't part of the crop rotations as since it will stay in that bed for the next 20 years or so.

Looking at the kitchen garden beds from a different angle.

I suspect I may end up amending my plans as I go along, depend on my health. But having the crop rotations worked out in general, makes it easier manage what to sow where. Now, I'm just waiting for Spring!


* * * * *

1. I'm putting together a post sumarising crop rotations (the reasons for, etc) for Solarpunk Action Week  (8th - 14th March). If there is an issue you'd like to see included, leave your request in the comments below.
2. If you would like to see these in more detail, I've uploaded them to Scribd.

Crop rotations for the vegetable beds

It's February, it's sunny, at the moment anyway, and I finally feel like the growing season has begun. So I thought it was time to work out what vegetables I plan on growing, and plan the vegetable bed rotations.

Garden design, showing where the vegetable beds are

You can see above where the vegetable beds fit into the overall garden design. And below is a layout of how I'm dividing up the beds for crop rotation. Most beds are 1m square, except for beds 6 and 11 which are 50cms square. The odd size is simply because I couldn't quite fit in 5m long beds, so went for 4.5m long beds. I am squeezing as much out of the space I can, even if it means slight odd bed sizes!

Numbering the vegetable beds for planning rotation

I have planned for a 4-year crop rotation. There are a lot of ways that you can plan your crop rotations. You could do a simple: brassicas, potatoes, legumes and roots, the latter including onions and garlic. You then plant everything together within their respective families, so with potatoes you could place tomatoes and aubergines, and in brassicas you would include cauliflowers, Chinese greens, brussels sprouts and kale.

Crop rotations plan, 2014- 2017

I've gone for something that is more detailed, as I also want to plan for what beds get the most sun. Beds 1 - 8 will get sun for a longer period (an extra 2-3 weeks at least) than beds 9 - 13. So I wanted to ensure that plants that need more sun, such as tomatoes, aubergines, squash and courgettes were to be rotated within the sunnier borders.

As beds 4 - 8 and 9 - 13 and parallel to each other, I'm going to create arches between some beds each year to extend how many climbing beans I can get in. So in 2014 I will be planting legumes in bed 4, with the climbing beans at the right side edge, so I can put in arches (using canes) over to the parallel bed 9 and grow more beans on the left edge of that bed. An added bonus is that this should also look pretty with the temporary arches and bean flowers and pods hanging down.

I also intend on throwing in some poppy, calendula and cornflower seeds into the vegetable beds, randomly, to add more prettiness(!) and to attract pollinators.

In the future, I plan on bringing the west-facing front garden into production. This gets quite a lot of sun all year around, even in winter, so will give me even more beds and yields to play with. I probably won't be starting on that until 2015, as I really want to focus this year on getting the back garden into production, with both vegetables and fruit, as well as flowers.

So the crop rotations are sorted. On with the seed sowing.

Crop rotation and lottie design

I've been spending a bit of time recently working on my crop rotations for my allotment, with the above being the outcome. Perhaps not the most exciting image you have ever seen, but I'm pretty darned pleased with it!

One of the reasons for it taking me ages is that not all the beds are built yet. The n/a for beds 13 & 14 in 2011 is for those to be built next year. However, beds 8 to 12 are only planned this year - so the rotations are depending on us actually digging in. Even if they don't get built the rotations should still hold.

At least, I hope so. It's been a lot of work trying to make sure that I'm rotating things in the right order. For instance, potatoes and tomatoes cannot follow each other in a rotation as they are the same family, and I have to make sure that there is 4 years between them being planted in a bed before returning to that bed. I use a 4 year crop rotation as a minimum as part of my management of pest and diseases.

There were quite a lot of other things to consider though when planning crop rotations. You need to be clear on what veggies you are going to grow, so that you can ensure that the same families are planted together. So the beans and peas, the legumes, are together, the parsnips and carrots together, etc. I worked out I had 8 key groups:

1. Legumes (peas, french beans and broad beans)
2. Potatoes
3. Brassica (cauliflower, broccoli, brussel sprouts and kale)
4. Roots (parsnips and carrots)
5. Chard (including spinach & beetroot)
6. Garlic (for other people it might be onions)
7. Tomatoes

I made Tomatoes it's own group as they take up quite a bit of room, but considered them and the potatoes together when planning to ensure a minimum 4 year rotation. Things like salads can go anywhere (and I'll mainly be growing these at home as quick growing cut and come again crops), as can corn and curcubits, though for planning purposes they are:

8. Curcubits (courgettes/zucchini and pumpkins/squash)
9. Corn

Other thins to consider are what crops should and shouldn't follow each other. For instance, winter tares (green manure) are rich in nitrogen, which produces strong leafy growth. So they are useful to be sown in autumn to be dug in the following springs, before you plant your brassicas. Brassicas being heavy nitrogen feeders, benefit from the nitrogen released by the winter tares.

However, you don't want to put potatoes in after winter tares, as you don't need to feed the foliage of potatoes, rather the tubers of the potatoes, in order to get good sized potatoes. So my plan in general is to sow winter tares in late summer, after I've pulled up the garlic crop. The tares will grow from autumn to spring, you dig them in, in spring, a few weeks before you plant out (or sow direct) your brassica seedlings.

So that's some of the thinking behind my crop rotation plan. You can download the spreadsheet if you like.

Finally, is there an actual lottie plan to match the crop rotations? Of course there is...

You can see that I didn't include the asparagus bed in the rotation. Being a long-term perennial, the asparagus can stay in that bed for about 20 years. So it's a while before I need to consider it in the rotation (about year 17 I'll start the new asparagus bed).

The strawberry beds are also left out of the main rotation plan. I'm going to dig up a third of the strawberry plants each year, starting this year, and replace them with runners, and rotate the strawbs that way. Apparently that should reduce the chance of strawberry mosaic virus, which can considerably reduce the yield and thereby reduce the amount of strawberry ice-cream I can make and eat. We couldn't have that. Also, strawberry plants seem to only last 2-3 years before starting to lose their vigour, and again, their yields, so another reason to give them a rotation.

Lastly, the shed, comfrey patch, compost bins will hopefully be built later this year, after beds 8-12 have been built and we have managed to win the war against the brambles and bloody couch grass. The greenhouse is my dream to help extend the season and give more more to chose from in winter. But it will probably be a couple of years before we have sufficiently destroyed the brambles and couch grass that are currently in its place. I'll be giving that area the old black plastic treatment. Oh, and a couple more years before I can afford to buy a greenhouse anyway.

Ok, this has probably been my most boring blog ever to anyone but me. But it feels good to have got the rotations and design done and it's my blog. So, well, ner.  ;-)