HORTICULTURE CERTIFICATION – PRACTICE QUESTIONS AND CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF.
CORE DOMAINS
- Plant Physiology and Anatomy
- Soil Science and Nutrient Management
- Integrated Pest and Disease Management
- Greenhouse and Nursery Production
- Ornamental Horticulture
- Vegetable and Fruit Crop Management
- Horticulture Law and Regulatory Compliance
- Ethics and Professional Standards in Horticulture
INTRODUCTION
*The purpose of this examination is to evaluate the technical competency and professional readiness
SECTION ONE: QUESTIONS 1–100
1. Which plant hormone is primarily responsible for apical dominance and is often used in rooting
compounds?
A. Gibberellins
B. Auxin
, C. Abscisic acid
D. Ethylene
🟢 B. Auxin
🔴 RATIONALE: Auxins, specifically indole-3-acetic acid (IAA), are responsible for apical dominance
and are the primary hormones used in synthetic form to stimulate adventitious root formation in
cuttings.
2. A soil test indicates a pH of 8.5. What is the most effective amendment to lower the pH for acid-
loving plants?
A. Hydrated lime
B. Dolomitic limestone
C. Elemental sulfur
D. Wood ash
🟢 C. Elemental sulfur
🔴 RATIONALE: Elemental sulfur is oxidized by soil bacteria into sulfuric acid, which effectively
lowers soil pH, whereas lime and wood ash would increase it.
3. Which pathogen is most likely responsible for "damping-off" in seed flats?
A. Pythium
B. Verticillium
C. Agrobacterium
D. Erwinia
🟢 A. Pythium
🔴 RATIONALE: Pythium is a water mold frequently associated with high moisture conditions that
causes the collapse of seedlings at the soil line, commonly known as damping-off.
4. What is the primary purpose of a "hard-off" period for greenhouse-grown transplants?
A. To increase nitrogen uptake
, B. To acclimate plants to outdoor environmental stressors
C. To prevent flower initiation
D. To encourage rapid root elongation
🟢 B. To acclimate plants to outdoor environmental stressors
🔴 RATIONALE: Hardening off gradually exposes greenhouse plants to lower temperatures,
increased wind, and higher light intensity to prevent transplant shock when moved to the landscape.
5. Which of the following is a symptom of nitrogen deficiency in most vegetable crops?
A. Interveinal chlorosis of young leaves
B. Purpling of leaf undersides
C. General chlorosis of older leaves
D. Tip burn on new growth
🟢 C. General chlorosis of older leaves
🔴 RATIONALE: Nitrogen is a mobile nutrient; when the plant is deficient, it translocates existing
nitrogen from older leaves to younger growth, causing the older foliage to turn yellow first.
6. According to the Worker Protection Standard (WPS), what information must be displayed at a central
location for agricultural workers?
A. Detailed profit and loss statements
B. Pesticide application records and safety data sheets
C. Employee performance reviews
D. Crop yield projections
🟢 B. Pesticide application records and safety data sheets
🔴 RATIONALE: The EPA’s Worker Protection Standard requires employers to provide accessible
information regarding pesticide applications, safety data sheets (SDS), and emergency medical
information.
, 7. Which irrigation method is considered the most water-use efficient for row crops?
A. Overhead sprinklers
B. Flood irrigation
C. Drip (trickle) irrigation
D. Furrow irrigation
🟢 C. Drip (trickle) irrigation
🔴 RATIONALE: Drip irrigation delivers water directly to the root zone, minimizing losses due to
evaporation and runoff, making it the most efficient method.
8. When grafting a fruit tree, what is the most critical requirement for success?
A. Identical fruit color
B. Perfect alignment of the vascular cambium
C. Using the same species
D. Grafting during the heat of summer
🟢 B. Perfect alignment of the vascular cambium
🔴 RATIONALE: The cambium layer is where undifferentiated meristematic cells divide; if the
cambium of the scion and the rootstock do not physically contact, the graft will fail to unite.
9. Which layer of the soil profile contains the highest concentration of organic matter and biological
activity?
A. A horizon
B. B horizon
C. C horizon
D. R layer
🟢 A. A horizon
🔴 RATIONALE: The A horizon, or topsoil, is where organic matter accumulates and where the
majority of root systems and beneficial microorganisms reside.
ANSWERS) PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF.
CORE DOMAINS
- Plant Physiology and Anatomy
- Soil Science and Nutrient Management
- Integrated Pest and Disease Management
- Greenhouse and Nursery Production
- Ornamental Horticulture
- Vegetable and Fruit Crop Management
- Horticulture Law and Regulatory Compliance
- Ethics and Professional Standards in Horticulture
INTRODUCTION
*The purpose of this examination is to evaluate the technical competency and professional readiness
SECTION ONE: QUESTIONS 1–100
1. Which plant hormone is primarily responsible for apical dominance and is often used in rooting
compounds?
A. Gibberellins
B. Auxin
, C. Abscisic acid
D. Ethylene
🟢 B. Auxin
🔴 RATIONALE: Auxins, specifically indole-3-acetic acid (IAA), are responsible for apical dominance
and are the primary hormones used in synthetic form to stimulate adventitious root formation in
cuttings.
2. A soil test indicates a pH of 8.5. What is the most effective amendment to lower the pH for acid-
loving plants?
A. Hydrated lime
B. Dolomitic limestone
C. Elemental sulfur
D. Wood ash
🟢 C. Elemental sulfur
🔴 RATIONALE: Elemental sulfur is oxidized by soil bacteria into sulfuric acid, which effectively
lowers soil pH, whereas lime and wood ash would increase it.
3. Which pathogen is most likely responsible for "damping-off" in seed flats?
A. Pythium
B. Verticillium
C. Agrobacterium
D. Erwinia
🟢 A. Pythium
🔴 RATIONALE: Pythium is a water mold frequently associated with high moisture conditions that
causes the collapse of seedlings at the soil line, commonly known as damping-off.
4. What is the primary purpose of a "hard-off" period for greenhouse-grown transplants?
A. To increase nitrogen uptake
, B. To acclimate plants to outdoor environmental stressors
C. To prevent flower initiation
D. To encourage rapid root elongation
🟢 B. To acclimate plants to outdoor environmental stressors
🔴 RATIONALE: Hardening off gradually exposes greenhouse plants to lower temperatures,
increased wind, and higher light intensity to prevent transplant shock when moved to the landscape.
5. Which of the following is a symptom of nitrogen deficiency in most vegetable crops?
A. Interveinal chlorosis of young leaves
B. Purpling of leaf undersides
C. General chlorosis of older leaves
D. Tip burn on new growth
🟢 C. General chlorosis of older leaves
🔴 RATIONALE: Nitrogen is a mobile nutrient; when the plant is deficient, it translocates existing
nitrogen from older leaves to younger growth, causing the older foliage to turn yellow first.
6. According to the Worker Protection Standard (WPS), what information must be displayed at a central
location for agricultural workers?
A. Detailed profit and loss statements
B. Pesticide application records and safety data sheets
C. Employee performance reviews
D. Crop yield projections
🟢 B. Pesticide application records and safety data sheets
🔴 RATIONALE: The EPA’s Worker Protection Standard requires employers to provide accessible
information regarding pesticide applications, safety data sheets (SDS), and emergency medical
information.
, 7. Which irrigation method is considered the most water-use efficient for row crops?
A. Overhead sprinklers
B. Flood irrigation
C. Drip (trickle) irrigation
D. Furrow irrigation
🟢 C. Drip (trickle) irrigation
🔴 RATIONALE: Drip irrigation delivers water directly to the root zone, minimizing losses due to
evaporation and runoff, making it the most efficient method.
8. When grafting a fruit tree, what is the most critical requirement for success?
A. Identical fruit color
B. Perfect alignment of the vascular cambium
C. Using the same species
D. Grafting during the heat of summer
🟢 B. Perfect alignment of the vascular cambium
🔴 RATIONALE: The cambium layer is where undifferentiated meristematic cells divide; if the
cambium of the scion and the rootstock do not physically contact, the graft will fail to unite.
9. Which layer of the soil profile contains the highest concentration of organic matter and biological
activity?
A. A horizon
B. B horizon
C. C horizon
D. R layer
🟢 A. A horizon
🔴 RATIONALE: The A horizon, or topsoil, is where organic matter accumulates and where the
majority of root systems and beneficial microorganisms reside.
