FFA Floriculture Practice Test

Which factor can influence the color of hydrangeas?

1. Soil nutrition

2. Temperature

3. Aluminum

4. Watering frequency

The correct answer is: Aluminum

The color of hydrangeas is primarily influenced by the availability of aluminum ions in the soil. In acidic soils, aluminum is more soluble and can be readily absorbed by hydrangea plants, resulting in blue flowers. Conversely, in alkaline soils, the availability of aluminum decreases, leading to pink flowers. Therefore, managing soil pH can directly impact the hydrangea's flower color due to the presence of aluminum. Soil nutrition does play a role in the overall health and vigor of the plant, but it is not the primary factor that dictates the flower color. Similarly, while temperature can affect the growth and blooming period of hydrangeas, it does not have a direct influence on the coloration of the flowers themselves. Regarding watering frequency, this is crucial for the plant’s health but does not affect the flower color since the relationship between aluminum availability and soil pH is the main determinant of the hue of the blooms. Adjusting the soil conditions to manage aluminum levels is key to achieving the desired color in hydrangeas.