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NYC HORTICULTURIST EXAM PRACTICE
QUESTIONS AND CORRECT ANSWERS
### Section 1: Soil Science & Plant Nutrition
**1. What does pH stand for?**
A. Plant hormones
B. Potential hydrogen
C. Phosphorus hydrogen
D. Percent humus
**Correct answer:** B
**Rationale:** pH stands for "potential hydrogen" — it
measures the concentration of hydrogen ions in a solution,
indicating acidity or alkalinity on a scale of 0–14 .
**2. What pH value is considered neutral?**
A. 5.0
B. 6.0
C. 7.0
D. 8.0
**Correct answer:** C
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**Rationale:** A pH of 7.0 is considered perfectly neutral —
neither acidic nor alkaline. Pure water has a pH of 7.0 .
**3. What pH range do most ornamental plants prefer?**
A. 4.0–5.5
B. 5.5–6.5
C. 6.0–7.0
D. 7.5–8.5
**Correct answer:** C
**Rationale:** Most ornamental landscape plants prefer a
slightly acidic to neutral soil pH in the range of 6.0–7.0. Within
this range, most essential nutrients are readily available for
plant uptake .
**4. A soil with a pH of 5.0 is how many times more acidic than
a soil with a pH of 7.0?**
A. 10 times
B. 50 times
C. 100 times
D. 1,000 times
**Correct answer:** C
**Rationale:** The pH scale is logarithmic — each unit
represents a 10-fold change in acidity. A pH of 5.0 vs 7.0 is a
difference of 2 units, so it is 10 × 10 = 100 times more acidic .
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**5. Which amendment is applied to LOWER soil pH (make it
more acidic)?**
A. Agricultural limestone
B. Wood ash
C. Elemental sulfur
D. Bone meal
**Correct answer:** C
**Rationale:** Elemental sulfur is applied to soil to LOWER pH
(increase acidity). Soil bacteria convert sulfur to sulfuric acid
over time, lowering the pH. It is commonly used for acid-loving
plants like blueberries, azaleas, and rhododendrons .
**6. Which amendment is applied to RAISE soil pH (make it
less acidic)?**
A. Sulfur
B. Agricultural limestone
C. Ammonium sulfate fertilizer
D. Aluminum sulfate
**Correct answer:** B
**Rationale:** Agricultural (Ag) limestone (calcium carbonate) is
applied to RAISE soil pH — to make acidic soil less acidic
(more alkaline). The calcium carbonate neutralizes soil acidity .
NYC HORTICULTURIST EXAM PRACTICE
QUESTIONS AND CORRECT ANSWERS
### Section 1: Soil Science & Plant Nutrition
**1. What does pH stand for?**
A. Plant hormones
B. Potential hydrogen
C. Phosphorus hydrogen
D. Percent humus
**Correct answer:** B
**Rationale:** pH stands for "potential hydrogen" — it
measures the concentration of hydrogen ions in a solution,
indicating acidity or alkalinity on a scale of 0–14 .
**2. What pH value is considered neutral?**
A. 5.0
B. 6.0
C. 7.0
D. 8.0
**Correct answer:** C
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**Rationale:** A pH of 7.0 is considered perfectly neutral —
neither acidic nor alkaline. Pure water has a pH of 7.0 .
**3. What pH range do most ornamental plants prefer?**
A. 4.0–5.5
B. 5.5–6.5
C. 6.0–7.0
D. 7.5–8.5
**Correct answer:** C
**Rationale:** Most ornamental landscape plants prefer a
slightly acidic to neutral soil pH in the range of 6.0–7.0. Within
this range, most essential nutrients are readily available for
plant uptake .
**4. A soil with a pH of 5.0 is how many times more acidic than
a soil with a pH of 7.0?**
A. 10 times
B. 50 times
C. 100 times
D. 1,000 times
**Correct answer:** C
**Rationale:** The pH scale is logarithmic — each unit
represents a 10-fold change in acidity. A pH of 5.0 vs 7.0 is a
difference of 2 units, so it is 10 × 10 = 100 times more acidic .
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**5. Which amendment is applied to LOWER soil pH (make it
more acidic)?**
A. Agricultural limestone
B. Wood ash
C. Elemental sulfur
D. Bone meal
**Correct answer:** C
**Rationale:** Elemental sulfur is applied to soil to LOWER pH
(increase acidity). Soil bacteria convert sulfur to sulfuric acid
over time, lowering the pH. It is commonly used for acid-loving
plants like blueberries, azaleas, and rhododendrons .
**6. Which amendment is applied to RAISE soil pH (make it
less acidic)?**
A. Sulfur
B. Agricultural limestone
C. Ammonium sulfate fertilizer
D. Aluminum sulfate
**Correct answer:** B
**Rationale:** Agricultural (Ag) limestone (calcium carbonate) is
applied to RAISE soil pH — to make acidic soil less acidic
(more alkaline). The calcium carbonate neutralizes soil acidity .
