Perennial crops, which produce food every year without the need for replanting, can be one of the most cost-effective and environmentally-friendly types of plants to grow commercially. There are generally four kinds of this crop, with some being more common than others. Many fruit varieties are naturally perennials, yet there are significantly less vegetable crops that come back each year. Generally, the grains most commonly consumed by humans are annuals; however, due to the environmental and financial benefits of perennial crops, some hybrid grains have been created that do not require replanting. There are a few legumes that fit this category as well, although their uses vary by location.
Several different fruits are perennial crops, including most common berry plants and those that are grown on trees. These include raspberries, blackberries, and blueberries, as well as apples, oranges, and bananas. Fruits such as figs, avocados, and grapes, as well as currants and apricots, are also perennial crops. Although many fruits are perennials, many are also not, including most melons and tomato varieties.
Generally, perennial vegetables are much harder to come by than fruits. Although most greens or lettuce-variety plants only grow as annuals, kale, radicchio, and collard greens are all perennial crops. Kale, a richly nutritious vegetable, actually remains green and viable through the better half of the winter in most cases, provided that it is cared for and only the leaves are picked. Asparagus and rhubarb are in this category as well, and are considered two of the easiest perennial crops for which to care.
Nearly all of the grains consumed by humans are annuals, and, as they are such a large part of the human diet in many countries, the commercial growth of them can, and does, have a negative impact on soil, not to mention the expense of production. For this reason, scientists are continuously working on cross-breeding annual grains with perennial crops in the same family to create a grain source that comes back year after year, reducing the need to rotate crops or replant every spring. As of 2011, one of the only perennial grains available is a wheat and wheat grass hybrid, which is good for producing flour.
There is not usually a large amount of perennial crops in the legume family. One of the most popular ones, especially in Japan and China, is kudzu, which is usually ground and used to create small cakes. The goa bean, also known as the asparagus pea, is only considered a true returning plant in very hot climates, and runner beans are extremely popular in the United Kingdom.
