Outdoor gardens brighten our living space. They may also produce vegetables for the larder and flowers for the table. A vast range of plants can be grown outdoors by gardeners at any skill level with a little basic information.
Originally, all plants were "outdoor plants." Beginning with ancient peoples, plants imported from other places became the first indoor plants. Outdoor plants are simply native or other plants that grow and reproduce with ease in a given geographical and climatological area.
Plants that grow, reproduce and die within one season are called annuals; those that repeat growth each growing season from the same plant are perennials. Biennials have a growth cycle of two years.
Plants may be hardy, tender or tropical, which refers to their toughness in a given area. Tender plants are easily killed by cold weather and tropical plants need warm air and high humidity to flourish.
Plants with similar hardiness and growth characteristics are native to or adapt easily to growth in geographic areas called growing zones, which are similar in landforms and climate. A plant that can survive without help in a growing zone is considered an outdoor plant.
Plants develop natural defenses as they adapt to environments. Some adapt by growing spines, thorns or tough skins. Others produce toxins that are found in their skin, fruit or sap.