Certified Professional Horticulturist (CPH) Practice Exam

Which environmental factor is most critical to consider when planting trees?

1. Soil temperature

2. Sunlight exposure

3. Wind exposure

4. Moisture availability

The correct answer is: Sunlight exposure

Sunlight exposure is vital to a tree's growth as it directly influences photosynthesis, the process by which trees convert sunlight into energy. Adequate sunlight enables trees to develop strong and healthy structures, produce leaves, and ultimately sustain themselves through their growth stages. Different tree species have varied light requirements; some thrive in full sun, while others prefer partial shade. Choosing a planting site that aligns with a tree’s light preferences fosters optimal health and productivity. While other factors like soil temperature, wind exposure, and moisture availability are also important, they do not have the same immediate and foundational role as sunlight. For instance, without sufficient sunlight, a tree may struggle to produce the energy necessary for growth, regardless of water or nutrient availability. Therefore, understanding and ensuring proper sunlight exposure when planning to plant trees is essential for their vitality and long-term success.