Day length is the most important cue for flowering in many plants. Plants that flower in response to day length are called long-day plants or short-day plants, depending on whether they require long days or short days to flower. Long-day plants include many summer-flowering plants, such as roses, lilies, and zinnias. Short-day plants include many fall-flowering plants, such as chrysanthemums, asters, and poinsettias.
Temperature is another important cue for flowering in many plants. Some plants require a period of cold weather before they will flower. These plants are called vernalization plants. Vernalization plants include many spring-flowering plants, such as tulips, daffodils, and hyacinths.
Water availability can also affect flowering in plants. Some plants require a period of drought before they will flower. These plants are called drought-tolerant plants. Drought-tolerant plants include many desert plants, such as cacti and succulents.
Nutrient availability can also affect flowering in plants. Some plants require a specific nutrient, such as nitrogen or phosphorus, in order to flower. These plants are called nutrient-deficient plants. Nutrient-deficient plants can often be fertilized to encourage flowering.
In addition to these environmental cues, plants also use internal cues to determine when it is time to flower. These internal cues include the plant's age, size, and overall health.
The combination of environmental and internal cues allows plants to accurately determine when it is time to flower. This ensures that plants produce flowers at the optimal time for reproduction.
