[Plot22]

This is my first year on the allotment and it has been typically haphazard with plants being chucked in as space is created.  I've tried to obey the basic rules, with some exceptions - I didn't know swede was a brassica so this ended up with the roots.

My brassicas are in two beds and I want to know, as I pull summer cabbages, can I fill the gaps with spring cabbages or should I put them in a new bed as part of a new rotation plan.  I hope this makes sense!!!

[mumofstig]

I always think that the brassica bed is the brassica bed until the spring, so carry on putting brassicas into it!

[SG6]

Have to say, and probably upset a few, but I don't think crop rotation is exactly relevant to an allotment.

It seems to be too small for crop rotation to be overly relevant.

My recollection of crop rotation is from medieval times when people rotated crops round 4 fields. At any one time one of the fields was fallow i.e. doing nothing. Do you intend to leave 1/4 of the allotment growing nothing?

For an allotment I would say that a good handfull of Growmore could easily render crop rotation redundant.

It isn't too hard to add relatively large quantities of manure to an allotment it isn't really appropriate to a field. So there are two easy ways to restore the nutrients to an allotment.

[Plot22]

My understanding of crop rotation was to try and prevent certain pests and diseases that are prevelant to a particular plant group by not growing the same family of crops in the same place for a few years.  What i'm struggling with is when the year starts and finishes as crops harvest at a different time.  I guess it's not an exact science.

[DD.]

My understanding of crop rotation was to try and prevent certain pests and diseases that are prevelant to a particular plant group by not growing the same family of crops in the same place for a few years. 

Quite.

Growmore will do nothing to stop the passing on of these diseases.

[sunshineband]

I always think that the brassica bed is the brassica bed until the spring, so carry on putting brassicas into it!

That's me!! Keep it all tidy and I don't get confused (well not too often anyway  )

[SG6]

Originally crop rotation was for the nutrients in the ground. Lugumes etc put nitrogen in that was then used by nitrogen hungry crops. Cannot recall the full cycle but pests and diseases were not part of it originally.

So as I said growmore and manure on an allotment will handle that side of it.

There is no way that if a part of the allotment has a pest or disease that it will not be present on the whole allotment simply owing to the small size of it.

So I would argue that crop rotation for pests and diseases will actually prove of little use either. As once present on one part, even small, they will spread without intervention if appropriate to the remainder.

Rotating crops could make it worse as if at say the top they if the crop they thrive on is planted elsewhere the next year the pest/virus will follow it. So it will spread possibly quicker.

[Chiswickian]

SG6 I have to say I could not disagree with you more!!!! So many diseases are soil-borne and not air-borne so that rotation will be beneficial. As one wee example, I have white onion rot in one area of my plot - on other areas all alliums are fine.

A lady on my site has done a wonderful job of making her plot into a garden - obelisks, ponds, climbing roses etc - and a lot of veg and fruit - but owing to her layout and design she can't rotate properly and over the last year or so she has noticed a lot of failures due to diseases - rusts, rots, etc. I am convinced it's because she cannot properly rotate her veg.

[SG6]

Crop rotation:
1: Root crop (potatoes): Growing and harvesting them breaks up the soil.
2: Alliums (onions): Anti bacterial effect, they clean the soil.
3: Legumes (Beans): Add nitrogen to the soil.
4: Brassicas (Cauli): Nitrogen hungry and benefit from the broken, cleaned soil.

My arguement isn't that it does not work, it is that the cycle appears to be to get the ground into a reasonable state and get nitrogen into the soil for brassicas. In an allotment environment it can be taken care of by a fork and a tub, box or sack  of whatever.

As to pests well a carrot fly will happily fly the length of an allotment to the new carrot patch as will cabbage root fly, onion fly, black fly, green fly and eel worms will also just burrow along to where the chosen crop is located. So rotation on an allotment scale will not deter lifeforms.

Virus and fungal diseases may be slowed but there is the allotmenteer who digs the ground over and spreads the "infected" soil around and also transfers it on their wellies.

Have a look at the discussion on poor garlic this year. What is the intended action for  next year? It is not to plant beans then brassicas, then potatoes then after 4 years give garlic another go, it is to dig in manure and chicken poo then stuff garlic back in.

[SG6]

Chiswickian, I know that plants sat in one place will eventually build up virus and fungal problems. Roses are well known for this as are raspberries.

Let me however put your situation like this(worst case - sorry): You are no longer able to perform a normal crop rotation. And owing to this you will eventually build up problems. (sorry, it sounds terriable doesn't it).

Reason:
Onions cannot go back to the area that is infected. The infection will be present for 8-15 years, say 10 as an average.
Next you cannot plant onions in the section adjacent to the infected area. High probability that the fungal infection will easily spread to the onions in this adjacent section and so infect more of the plot for a long time.

So that takes out 2 option for where the onions, and related alliums, can be placed next year. Say onions, spring onions, garlic and leeks.

When you dig the plot over do you change footware and use a new clean fork/shade on the infected area then change for the uninfected area? If not it is spreading.

As I said it probably sounds worse then it actually is but this is the apparent situation you are in and this is a limitation of simply where onions/alliums can go and potential spread by working the plot.

[Bozwell]

Most of the people up our allotment stick to a three year rotation plan. I on the other hand am sticking to a five year rotation, and used the advice I found by typing crop rotation in their search box on the RHS website. They offered advise on 3, 4, and 5 yr plans and said a five year plan is much better. They also give great advise how to split the plant groups up and what you can grow in each bed.
For example I can get a couple of crops out of my brassica bed in a season, when the summer cabbage and cauliflower have finished there is still time to pop in kale and swede which will run in to next spring, not a problem cause they will still be out of the ground before my next years crop of sweet corn and marrows/squashes need planting out to that bed.   

[Swing Swang]

With respect to crop rotation not being applicable on a small plot - consider the potager - planted for aesthetics rather than for rotation - and the French still eat their soups all year round!

I have a small patch (100sqm), and have a nominal five year rotation (I add corn and squash to the conventional plan), but when gaps become available I fill the land with whatever seeds I think will work and really don't get too stressed if I sow 'quick' brassicas such as rapini or pak choi in amongst gaps left by roots for example.

SS

[zazen999]

I have 9 long beds at the lottie, and the middle one is for the fruit with 2 seed beds at either end.

The other 8 are for any and all veg.

I just don't follow one crop with the same crop - and I interplant all my crops so I don't often get 'all' of the same types of veg going in. I rotate the main potato bed as that's the one that means the most to me; the brassicas are mainly rotated on the opposite bed, but the intervening beds are a mixed bunch. But, inbetween the brassicas I have onions, courgettes, and beans.

I also put alot of sacrificial flowers in [nasturtiums for example were covered in caterpillars last week but none on the brassicas], and leave alot to go to seed to save for next year, I aim to have a mix and match approach rather than solid beds of solid crops.

I also use onions and leeks to split the big beds down - like marking them into smaller beds.

[The Norfolk Turkey]

I guess its a bit like getting vaccines - you probably should do it given the time/opportunity etc, but its a calculated risk - how likely are you to actually succumb to said infection, and do you want to suffer the consequences?

My opinion would be that you probably should rotate - an adequately long rotation (like the RHS' 5 years), will mean viruses in particular will have no where to live for sufficiently long and die (they cant survive on their own); plants use different minerals from the soil (hence the use of leguminous plants in rotation) so theres a saving to be made too - why spend out a fortune on commercial products, when nature can lend a hand?

Weve got raised beds in the garden and have tried to divide them up to allow rotation in the future to allow us to: try different crops, reduce the amount of chemicals required, and save us a few quid (a decent infection could probably mean replacing 2 sq ton of soil!)!!

[Grubbypaws]

I am a complete beginner.

My husband has made me a 4' by 6' raised bed and I have planted it with brussels, cauliflower and kale; all my favorites. From your discussions does this mean I cant plant the bed in the same way for the next 5 years without replacing the soil?

Ouch, that would really dampen my enthusiasm!