Certified Professional Horticulturist (CPH) Practice Exam

When selecting plants for landscaping, what is the most important reason for limiting the number of plant species?

1. To limit competition for water among plants

2. To limit likelihood of multiple pest infestations

3. To ensure unity in the design composition

4. To allow plant species greater access to the soil's nutrients

The correct answer is: To ensure unity in the design composition

When selecting plants for landscaping, ensuring unity in the design composition is paramount for creating a cohesive visual appeal. Utilizing a limited number of plant species allows for a more harmonious look that reflects the desired aesthetic, whether that's a formal garden, a naturalistic landscape, or a themed arrangement. It enables the designer to play with color schemes, textures, and forms more effectively, resulting in a well-organized and pleasing design that communicates a strong visual message. While other factors like competition for water, pest infestations, and nutrient access are important considerations in plant selection, they primarily address ecological balance and plant health. However, the visual coherence achieved by using a limited palette of plants is a key component of successful landscape design, influencing how people perceive and interact with the outdoor space. Hence, focusing on design unity significantly enhances the overall effectiveness of landscaping efforts.