In the event of the same type of vegetable or related vegetable crop being planted on the same site season after season, it is only logical that the same type of nutrients will be taken out of the soil. Consequently you will find that your vegetables will become vulnerable to the same type of diseases and growth will diminish over time. Many diseases and pests are plant-specific.
Crop rotation is the method whereby different vegetable crops are planted in the same site as the seasons follow. In this way the soil in your vegetable garden can be replenished and you will also diminish the pests and diseases that may attack your vegetable crops by restricting their food supply and good conditions wherein the diseases may thrive.
On the whole vegetables can be grouped according to the family, species or type where they belong. These groups are as follows:
- The Cabbage family (Brassica): cabbage, cauliflower, Brussels sprouts, turnips, kohlrabi, radish and broccoli.
- The Potato family (Solanum): potatoes, tomatoes, chilies, brinjals (eggplants) and even goose berries.
- The Cucumber family (Cucurbita): cucumbers, watermelon, cantaloupe (sweet melons), pumpkins, squashes, butternuts, marrows and patty pans.
- The Onion family (Allium): onions, dill, spring onions, garlic, leeks and shallots.
- The Carrot/Root family (Umbelliferae): both yellow and white carrots, beets, beetroot, fennel, parsley and mint.
- The Leafy family (Compositae): lettuce, endive, all types of lettuce and chicory.
- The Legumes (Leguminosae): all peas and beans.
General tips for practicing vegetable crop rotation
- Do not cultivate the same or related species for two consecutive seasons on the same site in your vegetable garden.
- Do not plant vegetable crops with big root systems continually on the same site.
- Root vegetable crops will thrive in light soil and not rich soil. It is thus advisable to plant root crops after vegetable crops such as chilies, tomatoes and brinjals (eggplants) which are all heavy feeders.
- After harvesting vegetable crops such as cabbages, cauliflower, broccoli and Brussels sprouts it is advisable to rotate with legumes such as peas and beans to improve the nitrogen content of the garden soil.
There are some gardeners that do not practice crop rotation and still get away with a healthy vegetable harvest time after time. Though crop rotation makes sound sense, it needs to be understood to be fully workable. If you fertilize your vegetable garden soil correctly there is no nutritional benefit in rotating crops. You may argue that vegetables of the legume family will contribute greatly to the nitrogen content that was extracted from the air in the soil, which will benefit the next crop. There is no denying this, BUT a handful of LAN (Limestone Ammonium Nitrate) fertilizer can also make up for the difference in nitrogen content. On the other hand leguminous vegetable crops are eelworm susceptible and if you follow the legume vegetable crop with the same type of crop or even a crop that is also susceptible to eelworm infestation, the results can be devastating. For example planting carrots as the follow up crop for beans can be disastrous. It is thus imperative that you should rather consider soil-borne diseases and pests and not nutrition when you want to practice vegetable crop rotation. On the home vegetable gardening front it is mainly eelworm that attack ones vegetable crops. A good organic soil that has the optimum aeration level and a sufficient amount of beneficial organisms to counter pests and diseases is always the basis for a successful vegetable crop.