Crop rotations will help reduce diseases and avoid the buildup of pests. Before we made our 10-Year Plan for our gardens at Twin Oaks, in central Virginia, our basic scheme was to start the early spring crops in one garden to simplify the tractor cultivations. The whole of the other garden could then be disked up later in the spring. After that decision, the planning consisted of trying not to plant the same crop where it was planted in recent years, in an ad hoc way. After reading Eliot Coleman’s book The New Organic Grower, we were inspired to create a multi-year rotation, to maximize the productivity and health of our land, reduce diseases and pests, and make the planning work more predictable and easier on the brain.

We already had an established plan of which crops to grow and about how much of each we needed, based on records kept over many years. Our goal is to feed our community of 100 people all year, with a wide variety of fresh and preserved foods. If your goal is to supply a CSA or to fill a market booth for a certain number of weeks, your plan will look different from ours. You might not want so much winter squash, or white potatoes, for instance. You may want to have a nice long winter break, rather than practice season extension of greens. Perhaps there are certain crops you don’t grow because they are too time-consuming to harvest in large quantities. Each farm needs to customize its own plan.

Permanent raised beds
We now have a mixed system, with 60 permanent raised beds, each 4 x 90 feet, and 10 plots of  9,000-10,600 square feet. The 60 raised beds are cultivated manually or with a walk-behind tiller. We use them for crops we grow in small quantities, very short-term crops (like lettuce), things we need to fuss over (eggplant, apparently!), overwintering greens and leeks, and the very earliest crops like peas. Some beds will get two or three crops in one season. For the raised beds, we still don’t use a permanent rotation plan. We like the extra flexibility of the ad hoc method. If we have a crop failure, or something takes less or more time to mature than we expected, we can switch things around. The soil in these beds is very light and very fertile, so we get high yields, and we use the space very intensively.

We plan the raised bed crops twice a year: once in the winter for the crops planted before mid-July, and again in mid-June for the crops for the second half of the year. A vital tool for this planning is our “Colored Dots Plan”, a blank map of the raised beds with different colored dots for each vegetable family. At the year end, we put a vertical blue line after that year’s dots. Overwintering crops have the line run through the spot. It’s easy to fit many years’ worth of dots on the same map, which helps us see at a glance which crops have been planted where in recent years. Then we have a chart with the list of how many beds of what we want to grow and we work our way through, writing down the beds available for each crop family, then making decisions about what to put where. It’s like Vegetable Sudoku – it often seems there is only one right answer for each space. We always have to do a bit of  backtracking and some fudging of the rotation to a less than perfect match, but we do end up with a plan that uses the beds fully.

The main gardens
The main part of the garden is in three patches, with rows 180, 200 or 265 feet long. 265 feet is a very long row. I recommend breaks or gaps every 100 feet or 200 feet maximum. The initial cultivations here are done with a tractor and disks, and we also have a manure spreader for compost, a seed drill for cover crops, and a potato digger. For some crops we create temporary raised beds, but other crops are grown “on the flat”. Here we use our ten-year rotation, planting out major crops and also most of our succession crops of beans, squash and cucumbers. The first stage in planning our rotation was to figure out how big of an area we needed for each of our major crops.

Major crops
In terms of space occupied, our biggest crop is corn. In fact, sweet corn is such a space hog that we use three of our 10 plots for that! Obviously, we love it!

Here’s how the area for each of these crops adds up:
•sweet corn: 6 or 7 plantings of  about 3500 square feet each
•spring & summer planted white potatoes: about 7,000 to 9,000 square feet each.
•spring & fall broccoli and cabbage: 4,000 square feet in spring, 7,000 in fall.
•winter squash: about 8,200 square feet
•watermelon: about 9,000 square feet
•sweet potatoes: about 4,300 square feet
•paste tomatoes and bell peppers: 4,000 square feet for tomatoes, 2,200 square feet for peppers
•garlic: about 3,600 to 4,000 square feet
•fall carrots: about 3,600 to 4,000 square feet

Some people can work with numbers in the abstract. Others prefer a more visual planning method. We modified Eliot Coleman’s method, and wrote each major crop on a piece of graph paper cut to represent the relative area needed. Computer programs can be used instead, even a simple spreadsheet program. To help get a crop sequence figured out, we looked at crop families. We have three major crops of nightshades (Solanaceae): two of potatoes and one tomatoes and peppers together. We have two crops of brassicas, two or three of corn, and two vining crops.  Sweet potatoes are alone in their family (as far as our food crops go). Garlic and carrots are the only members of their families that are a major crop for us. It became clear to us that the 7,000 to 9,000 square foot crops would each occupy one plot in our rotation. So then we grouped other crops together to use about the same area. For example, two or three of our corn plantings together, spring broccoli with overwintered garlic, tomatoes and peppers together. We had an open mind about exactly how long a rotation we would have, but when our major crops fell into 10 sections, it suggested a 10-year rotation. You’ll notice that although we refer to this as a 10-year rotation, it isn’t 10 years between corn plantings, or potato plantings. It’s a 10-year plan that rotates crops.

We then set the graph paper pieces in a circle, like a clock face, and set about deciding what a good sequence might be. We started by spreading the three corn sections three or four years apart, and the three nightshade plantings likewise. We kept the winter squash three years after the watermelon. Some crops are said to do better following certain other crops, although just how well this folklore has been tested, I don’t know. Some of that information was not relevant to our rotation for our major crops, as it involved crops like onions, lettuce, or beets, which we grow in our permanent raised beds. And some information refers to beans or cucumbers, which we plant several times a year, and never a lot at once. We fit those crops in later, according to where space is available. Potatoes are said to do well after corn, so we put our spring potatoes after our late corn and our summer potatoes where the middle corn planting was in the previous year.

Another of our aims in devising our rotation was to improve our use of winter cover crops. For example, we wanted to add more legumes, such as crimson clover, to our winter rye. To get best value from crimson clover, we need to wait till it flowers – mid-April at the very earliest – before turning it under. So it’s best if we plant a later crop, such as later corn or June-planted potatoes, after that cover crop. Another factor is that crimson clover is best sown here before Sept. 20, so it has to follow a crop that is finished by then. For early spring planting, a preceding cover crop of oats (maybe with soybeans) is ideal, as it’s easiest to incorporate. Oats need to be sown here in August or very early September, so they need to follow an early finishing crop.

For a few years prior to the change to the new rotation, we had been planting our paste tomatoes, and sometimes our peppers, into a mowed cover crop of winter rye and hairy vetch. This reduces inversions of the soil, and the vetch (if plentiful) can supply all the nitrogen the tomatoes need. We like using this no-till method and wanted to incorporate that into our big scheme, too. The rye and vetch is best sown here in early to mid-September. So there was another restriction on which crops the tomatoes could follow. In fact, these “restrictions”  are more like the rules to a game, and provide a structure to work within. Looking on the process as a challenging puzzle or game is a constructive approach to take, I believe.

We formed several “strings” of a few crops that followed each other well. The spring broccoli can be followed by the rye and vetch in good time to grow a thick stand for the tomatoes the next year.  The late corn can be undersown with oats and soy to provide a winter cover crop that is easily incorporated before a March planting of potatoes. The garlic can follow the early corn. The fall carrots can follow the garlic harvested in June. The middle corn is finished in time to establish rye and crimson clover, which will do well and produce lots of nitrogen and biomass before we need to plant the June potatoes. After some shuffling of paper pieces, we came up with a workable sequence for all the major crops, and also a transition plan for a couple of years to get us onto the new rotation.

After a couple more years, we made a few improvements, and discovered Austrian Winter Peas as a leguminous cover crop. They can be sown as late as the end of October here, and also are said to reduce the incidence of Septoria Leaf Spot in following tomato crops, so we now add them to our no-till rye and hairy vetch planting. We also found that we could tighten up the rotation and keep a 10-year plan, but have one plot be in cover crops all year round, to replenish the soil. We follow the spring planted potatoes with the fall broccoli and cabbage transplanted in August. Then we undersow those brassicas with a mix of clovers about a month after transplanting. The following spring, we bush hog the old brassica stumps, and let the clovers flourish. If the plot is not too weedy, we let the clovers grow all summer, mowing to prevent the crimson clover seeding. If the weeds are too bad, or the clover stand not thick enough, we turn the clover under once the warm weather has arrived, and sow sorghum sudan hybrid with soy. This gets mowed when the sorghum sudan is 4 feet tall, to encourage deeper rooting for better soil drainage, and can stay until killed by the frost. If we still have the clovers, we turn them under and sow oats in August. And so we get two food crops in one year and none the next, from that plot. Plus, it is ready early the following year for our first corn planting.

Another example of  “tightening up” is that after the early corn, we divide the plot in two, sow half to oats (for the next year’s spring broccoli) and mow the other half from time to time until late fall, then plant garlic there. The garlic is harvested in June, followed by buckwheat and soy, and then sown with our fall carrots in late July or early August. That half a plot grows three food crops in two years. A less elegant part of our rotation has one plot divided in two, for spring potatoes and cucurbits (cantaloupes/musk melons and cucumbers). Because they are planted at very different times, this involves some fussy tractor cultivations. As I write this article, I start to get excited with the idea that a reader might see some improvements we could make and email me!

We drew up our 10-year rotation on a piece of card with a small central disk attached by a brass paperclip so it can rotate each year to show which crops will be planted in which plots. We call this our Rotation Pinwheel.  We are still using the same piece of card we made in 1996, and 2007 is the second year that we are repeating the sequence. The card has seen quite a bit of  “white-out”, and  small revisions!

Fitting in succession crops
Each winter, part of our annual planning is to fit in the minor crops, the succession plantings of beans, summer squash and zucchini, cucumbers, cantaloupes and anything we didn’t manage to find room for in the permanent raised beds. We start with a blank map of the plots and write in which major crops will go in which patch, using the 10-year Rotation Pinwheel. Off in the margin, we write when that patch will need disking, or other tractor work.

Usually, we have four Spring diskings:
#1 as soon as possible in February, for the Spring broccoli, cabbage and potatoes.
#2 in March, for the early corn
#3 in mid-April, for middle corn, cantaloupes, watermelon, winter squash, and sweet  potatoes.
#4 in early May, for summer potatoes, late corn, late cantaloupes.

Factors to consider are: minimizing the number of disking occasions, to make tractor drivers’ lives easier; disking as late as possible in order to get maximum value from the winter cover crops; but also disking far enough ahead of planting to allow the cover crop to break down in the soil (dead oats are relatively quick, rye takes more than three weeks).

Then we block in the area needed for each major crop, checking our Crop Review notes for changes in row footage, and calculate the remaining space in each plot.

We have a special Succession Crops Planning Sheet, where we list the spare spaces in the plots in order of availability, and the crops we hope to plant (in date order). Then we pencil in arrows, fitting the succession crops into the spaces available. When we are satisfied we have the best fit, we fill in the details on the map and transfer row feet numbers to the seed order, and transfer any special notes to the Calendar and the Greenhouse Schedule. (We have a schedule of winter planning steps to keep us on track through the all-too-brief hibernation season)

Why bother?
This crop planning might sound laborious, but for us it’s very worthwhile. The division of the gardens into 10 plots gives us mental and psychological advantages, in that we don’t have to actively think about the whole of the area all of the time. In spring we are “opening up the rooms” one or two at a time to plant. By the beginning of July, everywhere is in use. And in August, we start to put the plots “to bed” with their winter cover crops. This annual expansion and contraction (breathing out and breathing in) of  the space needing our attention helps us to stay sane and focused and keep perspective.

This system helps us get high productivity from our land, and take good care of it. Some years ago, when I was researching plant spacing for watermelons, trying to plant as closely as possible, consistent with keeping the melon size and yield up, I spoke with a farmer in the Midwest. He said  if farmers in that region wanted more watermelons, they would just plow up more land, not try to plant them closer.  That was a useful perspective for me to consider.  Here on the East Coast, land for farming is less available and more expensive. I come from the UK where land is even more expensive. And here at Twin Oaks, the land available for vegetable gardening is finite. The whole community would want to consider any application from us to expand the area we use. All the fields are fully used, by our dairy program, or for hay. We’re not enthused about clearing woodland. We’d rather use our cultivated areas intensively, and this sort of planning allows us to do that.

Another big advantage of having a planned rotation is that we don’t any longer have to figure out all the crop placements afresh each spring. We save time, and we know we have a basic plan which will fit together well.

Probably the biggest snag for us in using this rotation is that it doesn’t take account of parts of the gardens which are lower-lying and wetter, and so less suitable for some crops. This year was the year for planting the tomatoes in one of our potentially wetter areas, and my understanding of the El Nino Southern Oscillation system was that we could expect a wet spring. So in the fall, before sowing our cover crop, we made raised beds. We mowed the no-till cover crop, crossed our fingers and planted. No wet spring! For us, making temporary beds, or planting on ridges in the wetter areas is easier than changing the crop rotation.

Resources
•The New Organic Grower by Eliot Coleman is very helpful on devising and planning rotations. $24.95 plus $5 shipping from GFM at 800-307-8949 or www.growingformarket.com.
•Managing Cover Crops Profitably by SARE. (Sustainable Agriculture Research and Education): http://sare.org/publications/
The whole book, recently revised, is online:
< http://sare.org/publications/covercrops/covercrops.pdf>