Seasonal Plants: Understanding Annual, Biennial, and Perennial Plants

Seasons and Growing Seasons

• Seasons in a year vary by temperature, weather, amount of daylight, and rainfall
• Plants respond to these seasons in different ways
• A growing season, or frost-free season, is a period when plants can grow, limited by climate, elevation, frost days, temperature, daylight hours, and rainfall

Types of Plants

• Annual plants complete their life cycle in one growing season
• Biennial plants require two growing seasons to complete their life cycle and die
• Perennial plants live on for many years, flowering every year
• Annuals produce seeds and die after a year or two, while perennials can come back year after year without dying

Growing Season Measurement

• Measured in two ways: temperature and frost-free days
• Length of the growing season has increased in some places due to climate change
• Longer growing season can lead to invasive species and increased water needs

Annual, Biennial, and Perennial Plants

• Annuals: complete life cycle in one growing season, die after producing seeds
• Biennials: require two growing seasons, produce flowers and seeds in the second season, then die
• Perennials: live on for many years, flowering every year

Types of Annuals

• Hardy annuals: can tolerate some freezing weather and light frost
• Half-hardy annuals: tolerate cold and damp weather as well as moderate frost
• Tender annuals: cannot tolerate cool temperatures or frost
• Ephemeral annuals: have a short lifespan, often found in deserts

Perennial Cycle

• Perennial plants survive for multiple growing seasons
• Short-lived perennials may live for a few years, while long-lived perennials may live for tens or hundreds of years
• Perennials can survive extreme temperature or water changes through structures like roots, rhizoids, bulbs, or tubers