Crop Rotation is a technique used in organic gardening in order to prevent pest and disease build up as well as to replenish the soil. This is done by rotating the position of crop families from year to year. Many adult pests and their offspring overwinter in the soil. By rotating your crops you can disrupt the insects’ life cycle and prevent outbreaks.
Oftentimes pests attack plants within the same family. For example, leaf miners attack members of the Goosefoot Family, such as spinach and Swiss chard. If members of this family are planted in the same space year after year, pest populations can increase, reaching unmanageable numbers very quickly. Crop rotation is a strategy that helps to prevent this problem. By planting members of the Goosefoot Family in different locations throughout the garden you can ensure that the leaf miner population is kept in check.
Members of the Nightshade Family are another example; tomatoes and potatoes share the same disease problems. For example, the fungus that causes late blight can survive in potato tubers left in the ground from the year before. If you plant tomatoes in this same area the following year they will be sure to get the disease.
Another reason to rotate different crops in a particular area is for soil health. Different plants/plant families have different nutritional needs. Varying the crops in an area each year will help keep the nutrient level of the soil balanced. Legumes planted as part of the rotation will help to replenish usable nitrogen in the soil.
Steps to crop rotation:
1. Organize your garden into different areas, either by garden beds or groups of beds.
2. Get to know your vegetable families.
3. Plant each area with members of the same family.
4. Rotate these plantings each year. Allow for at least three years before you re-plant the same family in a given space. This is especially important for the Nightshade Family.
If your space is limited and you are unable to plan for a different area of your garden for each vegetable family, you are in luck! Some vegetable families grow well together. Here are a few tips for planting with limited space:
- Corn can be planted with members of the Squash Family or beans.
- Members of the Onion Family can be planted with any group except for legumes.
- Leafy crops can be planted with members of the Cabbage Family.
- Root crops such as beets, carrots and radishes can be planted among any group, and replanted in various areas as succession crops.
- Use companion planting methods to make the most of your garden space.
- Keep track of your plantings and rotation and note your successes.
A few examples of rotation plans are provided below:
This simple rotation suggested by the Penn State Cooperative extension offers a good rotation scheme for those with small areas. This rotation allows room for creative companion planting. The principles behind this plan are pretty simple. Crops in the Cabbage Family are heavy feeders; they do well when they are planted after legumes. Nightshades are planted together and only planted in the same area every four years. Squash and corn do well together and save space when planted together.
Eliot Coleman, author of the “Four-Season Harvest”, developed the rotation to the left. If you have enough room for eight different groups, this rotation is very well planned out. Coleman reasons that both potatoes and squash are good “cleaning” crops, meaning that they cover the soil and prevent weeds from taking root. These plants are then followed by root crops. Beans add nitrogen to the soil for tomatoes and peas add more nitrogen, building up nutrients in the soil for heavy feeders like the Cabbage Family and corn. Potatoes are planted opposite tomatoes in the rotation, leaving three years between these pest prone plants.