Annuals are plants that flower and/or set fruit in one growing season. Most vegetables are annuals as well as domesticated grains. Vegetables such as carrot and celery are biennials grown as an annual whereas tomato and bell pepper are perennials and grown as an annual. Annuals grow well mixed in with perennials and biennials. There are also ornamental flowers that are perennials in one region and an annual in another.
An annual can produce seeds that continue the life cycle in as little as one month; others may take longer. Desert annuals, or therophytes, have a short seed-to-seed cycle spending most of its life in seed form protecting itself from the dry conditions.
Summer annuals are vegetables and flowers that sprout, flower, set fruit, produce seed and die before the cold temperature sets in.
Winter annuals grow during the cold months setting flower and seed. Seeds of the winter annual germinate in the fall when the soil temperature is cooler versus the summer annuals which needs warmer soil.
Winter annuals are usually short, closer to the ground, where snow cover provides protection from the coldest temperatures. Winter annuals also help prevent soil erosion as well as providing shelter and feed for wildlife. Some winter annuals are nothing more than weeds but are still beneficial to the ecological cycle. Winter annuals can become hosts for pests or disease that can remain in the soil harming the crop that is to be cultivated.
Image Caption: Pisum sativum pods. Credit: Rasbak/Wikipedia (CC BY-SA 3.0)