Certified Professional Horticulturist (CPH) Practice Exam

A customer tells you that they planted Impatiens in full sun next to the driveway. The plants look great in the morning but terrible in the late afternoon. What is the likely cause of the problem?

1. Nightly watering may have promoted growth of spider mites which cause flowers to wilt

2. These shade-loving plants are planted in full sun next to a hot surface

3. Chemicals from the asphalt are leaching into the ground and are being absorbed by the roots

4. Nightly watering contributes to soil erosion and loss of essential nutrients

The correct answer is: These shade-loving plants are planted in full sun next to a hot surface

The scenario presented highlights that the customer has planted Impatiens, which are indeed shade-loving plants, in a location that receives full sun throughout the day. Impatiens thrive in partial to full shade and are known to struggle with prolonged exposure to sunlight. When planted in full sun, especially next to a hot surface such as asphalt, these plants can become stressed due to excessive heat and light. In the late afternoon, when temperatures are typically highest and sunlight is most intense, the Impatiens may not be able to effectively manage the stress caused by these conditions. This can lead to wilting, leaf scorch, and overall poor appearance, especially after a day of harsh sunlight. The combination of the heat radiating from the driveway and the plant's inherent shade preference creates an environment that is unsuitable for its health. Understanding the light and temperature requirements of specific plants is crucial in ensuring their successful growth and longevity, which is why placing a shade-loving plant like Impatiens in full sun is likely the primary reason for the observed decline in their condition during the later hours of the day.