An heirloom plant, heirloom variety, heritage fruit (Australia and New Zealand), or (especially in Ireland and the UK) heirloom vegetable is an old cultivar that is maintained by gardeners and farmers, particularly in isolated or ethnic minority communities in western countries. These may have been commonly grown during earlier periods in human history, but are not used in modern large-scale agriculture.
In some parts of the world, notably the European Union, it is illegal to sell seeds of cultivars that are not listed as approved for sale. The Henry Doubleday Research Association, now known as Garden Organic, responded to this legislation by setting up the Heritage Seed Library to preserve seeds of as many of the older cultivars as possible. However, seed banks alone have not been able to provide sufficient insurance against catastrophic loss. In some jurisdictions, laws have been proposed that would make seed saving itself illegal.
Many heirloom vegetables have kept their traits through open pollination, while fruit varieties such as apples have been propagated over the centuries through grafts and cuttings. The trend of growing heirloom plants in gardens has been returning in popularity in North America and Europe in recent decades.
Before the industrialization of agriculture, a much wider variety of plant foods were grown for human consumption. During the 19th and early 20th centuries the diversity was huge. Old nursery catalogues were filled with plums, peaches, pears and apples of numerous varieties. In modern agriculture in the industrialized world, most food crops are now grown in large, monocultural plots. In order to maximize consistency, few varieties of each type of crop are grown. These varieties are often selected for their productivity, their ability to withstand mechanical picking and cross-country shipping, and their tolerance to drought, frost, or pesticides.
Heirloom gardening is a reaction against this trend. In the Global South, heirloom plants are still widely grown, for example, in the home gardens of South and Southeast Asia. Before World War II, the majority of produce grown in the United States were heirlooms.