Crop Rotation for Vegetable Gardens
We’ve all heard of the benefits of crop rotation in large scale agriculture. And we all know that those benefits can transfer to our home vegetable gardens. Even the smallest of gardens can benefit from crop rotation, even if crops are only moved a few feet each year. Crop rotation is especially important to the organic grower because it precludes many of the problems that lead to the use of chemical pesticides and herbicides.
Exactly what are the benefits? Rotating crops is especially critical to preventing disease from getting a foot hold on certain vegetables you might plant. The bacteria and spores that attack specific plants can survive winters and infect those plants again the following year. The good news is, once in the soil they can’t travel far. You’ll do more to move them around with your spring cultivation than anything they might do on their own. If you plant the same hosts that those diseases are looking for, you’ll provide them with the ability to re-establish and become even more severe. Plant something from another group of vegetables that don’t normally host the problems, and they’ll eventually disappear.
The same thing goes with garden pests. Many of the insects that attack your vegetables live in the soil. Most are attracted to certain host plants — why do you think they call a cucumber beetle a cucumber beetle? Planting their host in the same spot year after year almost guarantees an infestation.
There are other good reasons to rotate crops. Different families of plants make different nutrient demands on your soil. Plant the same family in the same spot year after year and you’re sure to exhaust the soil of certain nutrients. Rotating different plant families through specific sections of your garden will help prevent depletion of certain nutrients and keep your soil well-balanced. Also, the different root depths reached by various vegetables will help prevent soil compaction. Plant shallow rooting lettuce in the same place year after year and only the top layer will remain friable.
Crop rotation can also increase soil health in other ways. How many of us have planted nitrogen fixing crops like beans and other legumes in the spot where heavy feeders like tomatoes were planted the year before?
So how do you know which vegetables should follow which in your garden? There are charts that help (scroll down). But the principles behind crop rotation are fairly straight-forward. The crop you choose to follow the previously grown crop should differ in lifecycle and associated cultural practices such as the rooting, soil nutrient needs, and moisture needs of various families of plants. Knowing the family of plants each vegetable belongs in — onions, peas, grasses (like corn), gourds, nightshades (peppers tomatoes, eggplant) — is invaluable. You can find clear directions for which family should follow others here (scroll down). You’ll see the crop rotation principle at work.
Remembering where your crops were planted in previous years is critical to planning where the crops will go come next spring. This is where a garden journal is invaluable, especially one with garden layouts drawn (as I like to do) on graph paper. Your memory might be better than mine, but I’m always surprised how confused I can be about where things were planted last year. This happens to the best of us, especially if we’ve been gardening the same plot for more than a few years. When you draw up your garden plan, it’s wise to consult the plans you drew from previous years, if you have them. With a journal, you will.
While a three year rotation is recommended, even just alternating the same crops every other year — often a necessity in small garden plots — is worthwhile. And while its recommended that you move crop plantings as far away as possible from their previous location, even a foot or two can make a difference. Some gardeners, like here, compartmentalize their plots, moving them from A to B to C (and D and beyond) every year. This makes for easily remembered rotations. Dividing your garden space into quadrants and then rotating crops through the various qundrants is an easy way to keep up with crop rotation. Didn’t keep records of what and where you planted? Sit down and sketch last year’s garden out now, before it becomes confused with the plans for this year’s garden. You — and your crops — will be glad you did.