The resurgence of heirloom recipes is an outgrowth of the heightened interest in growing heirloom vegetables and plants. An heirloom plant, heirloom variety or heirloom vegetable is an open-pollinated cultivar that was grown in earlier times, but is not used in modern large-scale agriculture.
In modern agriculture, most crops are grown in large plots and to maximize consistency, with minimal plant variety. In determining what varieties are planted, growers will often look at the plant’s ability to withstand mechanical picking, cross-country shipping, pesticides and severe weather conditions. Nutrition and flavor are often secondary considerations. As a result, the interest in growing heirloom plants has increased. Some gardeners grow heirlooms for historical interest; others want to taste the different varieties of vegetables; and finally some have an interest in organic gardening.
To be an heirloom, a plant must be “open-pollinated”, meaning it will grow “true to type” and produce plants like the parents from seed. This excludes nearly every hybrid. Open pollination allows the same cultivar to be grown simply from seed for many generations
There is no consensus on how old a plant has to be to be considered an heirloom plant. Some thought is that plants originating after 1951 should not be considered heirloom, as that was when there was wide-spread introduction of hybrid varieties. Generally, the heirloom designation is not given to any plants that are grown commercially and on a wide-scale.
Typically, heirlooms have adapted over time to whatever climate and soil they have grown in. Therefore, they are often resistant to local pests, diseases, and extremes of weather.