Why rotate?
An allotment usually has relatively large "blocks" of crops, each hosting plants of one family. Growing the same crop in the same "block"/bed, year after year, causes two problems:-
- an ideal environment in which the pests and diseases for that vegetable will thrive;
- and the crop makes the same demands on the same specific nutrients it needs.
Put the two together, and you have a recipe for epidemics striking down ever more sickly plants!
How to rotate?
I found rotation plans in gardening books frustrating - I don't suppose I'm the only one who doesn't work their ground like that! I have spaces after early crops, (for a second crop, or for a green manure), and I keep popping seeds into odd empty spaces, whatever my paper plan says!
So I'll try to express clearly the "tools" I use - the principles and ideas that go into decisions about what goes where, when.
Basics
- Rotation is essential - the KISS principle, just keep the crops moving! Leave at least a year, or better a 2/3 years gap, before a crop returns to the same bed.
- Set aside an area for the "permanents" - the fixed beds for asparagus, comfrey, fruit bushes, herbs, rhubarb, and strawberries.
Step 2 - Know your crops strengths and weaknesses.
- Rotation applies to vegetable/plant families, NOT to individual crops.
- Think about how susceptible your crops are to soil-borne disease, bugs and pests.
- Some crops "must have" rotation, as they are VERY susceptible to disease and pest damage - potatoes and brassicas are obvious examples of crops which should not return to the same bed for 3 to 4 years.
- Some crops "are keen on" a rotation - the onion family (unless you have white rot); and the carrot family. Leeks are probably the least susceptible of all the onions, so they are quite flexible - and can fit in a number of places (mine go in after early potatoes).
- Some crops "are generally not that choosy - but it's worth humouring them" - peas and beans.
- And some, bless their cotton socks, are just "eager to please", and can go anywhere - beetroot, the leaf-beets, spinach, lettuce, the squashes and cucumbers, sweetcorn, salsify and scorzonera.
- Some crops benefit the following crop.
- Beans and peas fix nitrogen - so let nitrogen-hungry brassica follow them (possibly in the same season);
- Potatoes don't like lime, so follow them with liming in the winter; next season, plant the crops that like lime most (brassica, or beans/peas);
- Roots dig deep and break up the soil - so follow them with potatoes;
- Peas and beans like the rich deep dug soil left behind after the potatoes;
- Brassica like a firm soil, so don't follow potatoes very happily;
- The onion family are generally happy in the firm soil left by the brassica.
- Working out all the permutations gives an "ideal" 5 or 6 year sequence like this -
- Year 1 - Beans/peas,
- Year 2 - followed by Brassica,
- Year 3 - followed by Onion family,
- Year 4 - followed by carrots/parsnips,
- Year 5 - followed by potatoes, (add lime in winter),
- and back to the beginning
- Think of winter treatments -
- Digging in manure in the winter before the potatoes;
- Adding lime before the peas and beans;
- Adding compost before the brassicas;
- Growing a winter cover of green manure as preparation for the onion, and roots crops.
Step 3 - Real World!
Now think about what you want to eat!!!!!
- Knock out the families you DON'T want to grow;
- Merge families when you don't want that much - I merge onions and carrots/parsnips - which fits what we eat (and the fact I can't grow succesful carrots!);
- Slip in the "friendly" veg - the squashes, sweetcorn, beets, spinach and lettuce;
- And feel free to compress the 5 year cycle into 4, or even 3 years.
A few examples, to get us thinking!