Certified Professional Horticulturist (CPH) Practice Exam

When should one fertilize hardy ornamental plants to avoid winter damage?

1. Summer

2. Winter

3. Spring

4. Fall

The correct answer is: Spring

Fertilizing hardy ornamental plants in the spring is ideal because it allows the plants to establish strong growth as they emerge from winter dormancy. This timing helps the plants to utilize the nutrients effectively during their active growing season, leading to vigorous growth and increased resilience to winter conditions. Applying fertilizer in the spring promotes robust root and foliage development, which can enhance the overall health of the plants. If plants are well-nourished in the spring, they are better equipped to withstand environmental stressors, including harsh winter temperatures. While fertilizing in summer might encourage excessive growth that isn't as beneficial heading into winter, and fertilizing in winter could stimulate new growth that would be vulnerable to freezing temperatures, early fall fertilization can also lead to rapid growth that doesn’t harden off before winter. Thus, fertilizing in the spring strikes a balance by allowing the plants to strengthen while also preparing them adequately for the winter months ahead.