Crop rotation

 

The principle underlying crop rotation is that there should be a considerable gap in time between plantings of veggies from the same family in the same place. This helps stop particular diseases building up and also gives the soil a rest from particular burdens placed on it.

Veggies can be divided into the following 8 ‘groups’ (most of which are families or sub-families):

  1. Legumes (beans, peas, etc).
  2. Alliums (garlic, onions, etc).
  3. Roots (beetroot, carrots, celery, parsnip, etc).
  4. Cucurbits (cucumber, pumpkin, rockmelon, zucchini, etc).
  5. Solanums (capsicum, chilli, eggplant, potatoes, tomatoes, etc).
  6. Brassicas (broccoli, brussels sprouts, cabbage, cauliflower, kale, mizuna, pak choy, rocket, etc).
  7. ‘Anywhere’ (basil, coriander, lettuce, radish, silverbeet, spinach, etc).
  8. Perennials (asparagus, globe artichokes, rhubarb, etc).

Perennials are not relevant to crop rotation – they should be planted elsewhere. The ‘anywhere’ group are also not relevant – just plant them wherever and whenever you have gaps. So, the ideal is a 6-bed, 6-year rotation for the other 6 groups. If you have fewer beds, then you have to do one or more of three things:

  1. Combine some things: so, for example, plant alliums and roots in the same bed.
  2. Omit some things: so, for example, never plant brassicas.
  3. Plant a cool season crop (e.g. brassicas) followed by a warm season crop (e.g. beans) – or vice versa – into a single bed over the course of a year.

You then have to decide the order of how a bed should change over time. A principle here is that heavy feeders should, where possible, alternate with light feeders. So, for example, alliums (light) – solanums (heavy) – legumes (light) – brassicas (medium) – roots (light) – cucurbits (heavy).

Finally, you have to choose whether the annual rotation should be in Spring or in Autumn.

For a longer discussion of crop rotation, read Robin Gale-Baker’s article on the subject.

  12 Responses to “Crop rotation”

  1. Hi Guy, thanks for all the helpful information. Given that some crops are winter crops and others are summer crops, what do you recommend is the best thing to do in between these crops, in those beds? Would that be a good time to plant lettuce, spinach and herbs? Thanks, Natalie

    • Hi Natalie,

      What an excellent question!

      If you are only trying to grow one ‘crop-rotation crop’ in a particular bed in a particular year then, yes, plant your leafy greens in the time gaps. If you still have spaces then you can also plant legumes and (I think) alliums, as these don’t deplete the soil much.

      If, like me, you want to grow two ‘crop-rotation crops’ in some beds in some years, with the movement of the crop rotation happening between these two crops, then the issue of gaps doesn’t really arise. Rather, the issue here is that one often wants to plant the second crop before the first crop has been fully harvested, and one needs to juggle things to manage this. This is, for example, why I haven’t planted out my tomatoes yet.

      Guy

      • Thanks Guy, this leads me to another question (or two)!

        You mentioned growing two crops in some years; I’ve been wondering about whether it’s okay to plant successive crops of the same family in the same year before the rotation – e.g. for brassicas planting kale in summer and broccoli etc in winter, or for legumes planting green beans in summer and broad beans in winter.

        Alternatively, does each rotation have to be a full year or could you, for instance, plant tomatoes in summer followed by legumes in winter and brassicas the following summer in the same bed?

        Hope this makes sense! It’s complicated once you get into it. NB I dedicated a bed to alliums and root vegetables, planted beetroot, radish and horseradish then realised they aren’t from the root family at all, nor are turnip or potato (they come from the spinach/silverbeet, brassicas and solanum families, respectively). That’s stuffed that bed up a bit!

        Thanks again for all your help,
        Natalie

        • Hi Natalie,

          I think that most people only move their rotations once a year. I move mine between the Winter and Summer crops and thus grow green beans followed by broad beans or peas in my legume bed.

          I think that basically anything where you eat the root should count as a root in terms of crop rotation because they all break up the soil in a similar way. Potatoes are the exception: for various reasons, I think that you grow them elsewhere rather than in your veggie patch.

  2. Indicative of what? If you don’t want to do crop rotation, don’t do it. If you google something like “crop rotation scientific control study”, all sorts of studies appear which you can read the results of. I’m not aware of any small scale farmer or serious home grower who continues to grow the same crop in the same place year after year.

  3. I have seen the detailed recommendations and rationales for crop rotation in many sources. My question is, ‘does anyone know of any scientific, controlled studies of crop rotation as it applies to vegetable gardens (as opposed to big agricultural operations doing acres of a crop and using green manures in off seasons)?’

    I would love to believe this theory but the only controlled study I know of was that of Charles Dowding, English market gardener and author. And his results contradicted the need for rotation. Anyone?

    P.S. Please don’t repeat the rationales, I know why it is supposed to be useful. It’s just that often we find that our beliefs are not correct.

    • Dave,
      I came here after asking the google the same question. I suspect the dearth of replies is indicative.
      Such zeal from so many information sources for this wive’s tale.

      • Indicative of what? If you don’t want to do crop rotation, don’t do it. If you google something like “crop rotation scientific control study”, all sorts of studies appear which you can read the results of. I’m not aware of any small scale farmer or serious home grower who continues to grow the same crop in the same place year after year.

    • Would alternating growing green manure with mono crops be considered as crop rotation?

    • Keep in mind Charles Dowding has massive amounts of compost, which he dresses his beds with. Most home gardeners don’t have access to this amount of compost — green manure crops replenish the beds in lieu of inches of added compost.

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