Crop rotation is the practice of changing or alternating the crops in a given area of the garden. Rotating crops will stem the depletion of soil nutrients and prevent or reduce the build-up of pest and disease problems.
Crops that are heavy feeders and require more soil nutrients can be rotated with light feeders and soil-enriching crops, such as legumes.
Pest and disease problems can be minimized by not planting members of the same plant family in the same part of the garden more than once every three or four years.
Benefits of crop rotation
Crop rotation will benefit vegetable crops in two ways: first, it will prevent the build-up of soil-borne pests and diseases; second, it will allow for the replenishment and efficient use of soil nutrients.
Crop rotation is the practice of growing different crops, rather than the same vegetable or members of the same family of vegetables, in the same place each year.
To minimize pest and disease problems and to help renew soil nutrients, members of the same plant family should not be planted in the same part of the garden more than once every three or four years.
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Vegetable insect pests tend to feed on similar plants and members of the same plant family. For example, an insect pest that attacks and eats cabbage will lay its eggs before it dies. If cabbage or a member of the cabbage family is planted in the same spot the next year, the eggs of the insect will hatch and the pests will find exactly the food they need to continue the pest life cycle. Soilborne diseases–fungi, bacteria, and viruses–also can be hosted by specific plants as well. Removing host plants or alternating unrelated plants into the garden can break the cycle of pests and disease.
Crop rotation also helps prevent soil nutrients from being depleted. Vegetables draw on a wide range of soil nutrients for growth: nitrogen, phosphorus, and potassium are the key or major soil nutrients. Members of the same vegetable family usually draw the same nutrients from the soil.
Crop rotation will prevent the soil from wearing out: heavy nitrogen, phosphorus, and potassium-feeding crops such as tomatoes are rotated with soil-building crops such as beans which add nitrogen to the soil, and then with light-feeding crops such as onions.
How crops affect the soil
Crop rotation means moving vegetables around the garden to maintain soil fertility. By rotating crops from one spot to another each season—or even in the same season, you can preserve and even boost nutrients in the soil. Differing crops use different amounts of soil nutrients and a few crops add nutrients to the soil.
Some crops are heavy feeders; heavy feeders include tomatoes, broccoli, cabbage, corn, eggplant, beets, lettuce, and other leafy crops.
Some crops are light feeders: light feeders include garlic, onions, peppers, potatoes, radishes, rutabagas, sweet potatoes, Swiss chard, and turnips.
Some crops are soil builders: soil builders include peas, beans, and cover crops such as clover.
Rotating these three groups of crops makes the best use of nutrients in the soil.
Simple crop rotation
Simple crop rotation would plant heavy feeders in a dedicated planting bed the first year, followed by light feeders in the same bed the second year, followed by soil builders the third year. This rotation presumes there are separate planting areas big enough for all of the crops you want to plant in each of the three rotation groups.
If you have more than three planting beds and grow a large number of vegetables you can dedicate more than one bed to each group each year and still maintain the rotation.
Small garden crop rotation
Crop rotation in small gardens can be difficult; let’s say you only have one or two planting beds. In that case, you can still rotate crops simply to differing spots. You can follow a tomato with a bean one year after the other. Or you can replace a heavy-feeding crop such as broccoli grown in the spring or fall with peas in the spring or beans the next summer. You can also replace a heavy feeder with a green manure cover crop that feeds the soil; cover crops that feed the soil include dwarf white clover or hairy vetch.
Adding plenty of aged compost to planting beds before the season starts, after harvest, and as a side dressing during the growing season is another way to boost or replace nutrients in the soil, but that is not crop rotation.
Crop rotation by harvest groups
Crop rotation by harvest groups is a simple rotation strategy: rotate leafy crops, root crops, and fruiting crops. Harvest group rotation is not a precise crop rotation method (for example, peppers are light feeders and tomatoes are heavy feeders, but both are fruiting crops—but it is an easy way to group plants and to remember the rotation from one year to the next. A simple three-year crop rotation divides crops into their harvest groups:
- Leafy crops—lettuce, spinach, and members of the cabbage family such as broccoli, Brussels sprouts, cauliflower
- Root crops: carrots, turnips, parsnips, potatoes
- Fruiting crops (flowering crops): tomatoes, peppers, eggplants, cucumbers, squash
Into this mix, you can add cover crops to follow fruiting crops. Because fruiting crops are almost all summer crops—tomatoes, peppers, squash, melons, eggplants, they finish harvest in early autumn and their planting area can be replanted with a winter cover crop such as winter rye or fava beans. In spring, the cover crop is turned under, and leafy crops can be planted to continue the rotation. This rotation would look like this:
- Fruiting crop
- Cover crop
- Leafy crop
- Root crop
Major plant families and crop rotation
Crop rotation by plant family is perhaps the most traditional way to rotate crops though it can be difficult in a small garden of just one or two beds. In the plant family rotation, crops from the same family are not planted in the same spot any more often than every three years.
Crop rotation by plant family not only maintains soil fertility but also is the best way to avoid attacks by pests and diseases; specific pests and diseases tend to attack plants from the same family. By rotating plant families, pests are not easily able to find the plants they want to attack.
Notable vegetable plant families
- Squash family: cucumber, zucchini, winter squash, melons (heavy feeders)
- Cabbage family: arugula, broccoli, Brussels sprouts, cabbage, collards, kale (heavy feeders)
- Tomato family: tomatoes, peppers, eggplants (mostly heavy feeders)
- Bean family: beans and peas (soil enrichers)
- Lettuce family: endive, sunchokes, artichokes (heavy feeders)
- Carrot family: celery, parsnips, parsley, fennel, cilantro (mostly light feeders)
- Onion family: onions, shallots, leeks (light feeders)
- Spinach family: beets, spinach, Swiss chard (light to medium feeders)
Rotation by plant family will take some planning; you can match up light feeders to rotate with heavy feeders and separate the two with the soil builders.
- Onion Family (Amaryllis Family, Amaryllidaceae): Garlic, onions, leeks, shallots. These are light feeders. Plant these after heavy feeders or after soil enrichers such as beans. Plant onion family crops after heavy feeders. Follow onion family crops with legumes.
Cabbage Family (Brassica, Cruciferae): Broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, cress, kale, kohlrabi, radishes, turnips. These are heavy feeders. These crops should follow legumes. After these crops allow the garden to go fallow for a season or plant a cover crop or add plenty of compost and organic matter to the garden. After cabbage family crops build the soil for a season with a cover crop or soil-building compost or let the area sit fallow for a season after applying well-aged manure.
Lettuce Family (Composite, Daisy Family, Asteraceae): Artichokes, chicory, endive, lettuce. These are heavy feeders. Follow lettuce family crops with soil-building legumes.
- Bean Family (Legume, Leguminosae): Beans and peas, clover, vetch. These crops enrich the soil and soil builders. Plant these crops before or after any other crop family with one exception–do not plant beans after onions.
Beet Family (Goosefoot Family, Chenopodiaceae): Beets, spinach, Swiss chard. These are heavy feeders. Follow these crops with legumes.
Grass Family (Graminae): Grains–corn, oats, rye, wheat. Follow these crops with members of the tomato or Solanaceae family.
- Tomato Family (Nightshade Family, Solanaceae): Eggplant, peppers, tomatoes, potatoes. These crops are heavy feeders. Plant these crops after members of the grass family. Follow these crops with legumes.
- Squash Family (Cucurbitaceae): Cucumbers, melons, summer and winter squash, pumpkins, watermelon. These crops are heavy feeders. Plant these crops after members of the grass family. Follow these crops with legumes.
Carrot Family (Umbellifer Family, Umbelliferae): Carrots, celery, anise, coriander, dill, fennel, parsley. These are light to medium feeders. These crops can follow any other group. Follow these crops with legumes, and onions, or let the garden sit fallow for a season.
Simple four-year crop rotation plan
To follow a simple four-year crop rotation, divide your garden into four areas or plots: Plot One, Plot Two, Plot Three, and Plot Four. In each of the next four years, grow a different crop or different members of the four crop families in a different plot following this rotation:
• Plot One: Tomato family (year 1); Others–see list below (year 2); Bean family (year 3–but avoid planting beans where onion family crops have just grown); Cabbage family (year 4).
• Plot Two: Cabbage family (year 1); Tomato family (year 2); Others–see list below (year 3); Bean family (year 4–but avoid planting beans where onion family crops have just grown).
• Plot Three: Bean family (year 1–but avoid planting beans where onion family crops have just grown); Cabbage family (year 2); Tomato family (year 3); Others–see list below (year 4).
• Plot Four: Others–see list below (year 1); Bean family (year 2–but avoid planting beans where onion family crops have just grown); Cabbage family (year 3); Tomato family (year 4).
This four-year crop rotation intersperses members of the other vegetable families among members of the Tomato, Bean, and Cabbage families, and Others. Here is how they are grouped:
1. Tomato family and others (Solanaceae family)
Celeriac and celery
2. Bean family (Leguminosae family)
Broad (fava) beans
French (green) beans
3. Cabbage family and others (Brassica family)
Calabrese (Italian sprouting broccoli)
Squashes, zucchini, and pumpkins (marrow and courgettes)
Garlic–avoid planting beans in the same location after garlic
Leeks–avoid planting beans in the same location after leeks
Onions–avoid planting beans in the same location after onions
Shallots–avoid planting beans in the same location after shallots
Not included in crop rotation are perennial vegetable crops that grow in the same spot for several years in a row. Perennial crops include:
Small garden crop rotation
No garden is too small for crop rotation. A simple garden map showing where each crop is planted will help you plan and plant a different crop in that spot next year. To plan crop rotation in a small garden, map outstrips or blocks–rows or square feet–and avoid planting vegetables from the same crop family in that spot more than once every three years.
Crop rotation suggestions
Here are the major vegetable plant families and suggestions for crop rotation:
Onion Family, Amaryllidaceae: Garlic, onions, leeks, shallots. These are light feeders. Plant onion family crops after heavy feeders. Follow onion family crops with legumes.
Cabbage Family, Brassicaceae (Cruciferae): Broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, cress, kale, kohlrabi, radishes, turnips. These are heavy feeders. Plant cabbage family crops after legumes. After cabbage family crops build the soil for a season with a cover crop or soil-building compost or let the area sit fallow for a season after applying well-aged manure.
Lettuce Family, Asteraceae (Compositae): Artichokes, chicory, endive, lettuce. These are heavy feeders. Follow lettuce family crops with soil-building legumes.
Grains, Grass Family, Poaceae (Gramineae): Grains–oats, corn, rye, wheat. Follow these crops with tomato family plants.
Legume Family, Fabaceae (Leguminosae): Beans, peas, clover, vetch. These are soil enrichers. Follow legume family plants with any other crop.
Tomato Family, Nightshade Family, Solanaceae: Eggplant, peppers, tomatoes, potatoes. Nightshade family crops are heavy feeders. Plant these crops after grass family plants. Follow heavy feeders with legume family crops to rebuild the soil.
Squash Family, Cucurbitaceae: Cucumbers, melons, summer and winter squash, pumpkins, watermelon. Squash family plants are heavy feeders. Plant these crops after grass family plants. Follow heavy feeders with legume family crops to rebuild the soil.
Carrot Family, Apiaceae (Umbelliferae): Carrots, celery, anise, coriander, dill, fennel, parsley. Beets and chard, Amaranthaceae, can be grouped with the carrot family crops. These are light to medium feeders. Carrot family crops can follow any other crop. Follow carrot family crops with legumes or onion family crops.
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