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Penn State Extension Master Gardener Program Exam
Questions and Correct Answers Plus Rationales 2025
aligned with horticulture, integrated pest management (IPM), soil science, and Pennsylvania-specific gardening principles.
- What is the primary goal of the Penn State Extension Master Gardener Program? To educate the public using research-based horticultural knowledge The mission centers around providing community outreach and science- based gardening education.
- Which soil pH range is considered optimal for most vegetables grown in Pennsylvania? 6.0–6. This range allows for optimal nutrient availability for most vegetable crops.
- What is the best time to apply pre-emergent herbicides to control crabgrass in lawns? Early spring, when forsythia blooms Forsythia bloom time is a visual indicator that soil temperatures are warming enough for crabgrass germination.
- What is the primary reason for rotating crops in a vegetable garden? To reduce the buildup of pests and diseases Crop rotation breaks pest and disease cycles by removing their preferred host plants.
- Which of the following is a cool-season crop? Spinach Cool-season crops like spinach germinate and grow best in cooler temperatures.
- What type of mulch is best for vegetable gardens? Organic mulch like straw or shredded leaves Organic mulches improve soil structure and fertility as they decompose.
- Which macronutrient is most associated with promoting leafy vegetative growth? Nitrogen Nitrogen is essential for chlorophyll production and vegetative development.
- What is a common sign of overwatering in plants? Yellowing leaves and root rot Too much water deprives roots of oxygen, leading to decay and nutrient deficiency symptoms.
- What does the term “IPM” stand for? Integrated Pest Management IPM is a holistic approach combining multiple tactics for effective and sustainable pest control. 10.Which native Pennsylvania tree has compound leaves and produces edible nuts? Black walnut
Testing first ensures proper amendments and avoids over- or under- fertilizing. 17.Which is a recommended method to control aphids on garden plants? Spraying plants with a strong stream of water A strong stream can dislodge aphids without harming beneficial insects. 18.What causes blossom end rot in tomatoes? Calcium deficiency and uneven watering Even if calcium is present, inconsistent watering can prevent its uptake. 19.Which of the following is a benefit of native plants in Pennsylvania gardens? They require less maintenance and support wildlife Native species are adapted to local conditions and promote ecological health. 20.What does the term “perennial” mean? A plant that lives for more than two years Perennials regrow each season without needing to be replanted. 21.Which of the following is NOT a method of water conservation in the garden? Frequent shallow watering Shallow watering encourages weak roots and increases evaporation loss. 22.What does mulch help control? Soil moisture, temperature, and weeds Mulch retains moisture, regulates temperature, and suppresses weed growth.
23.Which tree is especially susceptible to the Emerald Ash Borer? Ash The Emerald Ash Borer targets ash trees and has caused significant damage in Pennsylvania. 24.What is the best way to reduce lawn chemical runoff into nearby waterways? Use buffer zones of native plants near water Buffer zones filter runoff and protect aquatic environments. 25.What part of the plant conducts photosynthesis? Leaves Leaves contain chlorophyll and are the primary site of photosynthesis. 26.What is the purpose of deadheading flowers? To encourage more blooms Removing spent blooms redirects energy into new flower production. 27.Why is proper plant spacing important? To improve air circulation and reduce disease Good spacing reduces humidity and fungal conditions. 28.Which plant disease is commonly caused by wet foliage? Powdery mildew Moist, shaded conditions promote powdery mildew growth. 29.When should bulbs like daffodils be planted in Pennsylvania? Fall Fall planting allows for root development before winter dormancy.
37.Which insect is a beneficial predator in gardens? Lady beetle Lady beetles consume aphids and other harmful pests. 38.What is the recommended method for testing soil texture? Jar and water sedimentation test This method visually separates sand, silt, and clay for texture analysis. 39.What should be added to clay soil to improve drainage? Organic matter Organic material improves structure and water movement. 40.Which of the following vegetables is best grown on a trellis? Cucumber Trellising supports the plant and improves airflow and fruit quality. 41.What kind of fertilizer is best for phosphorus deficiency? Bone meal Bone meal is high in phosphorus and supports root development. 42.What gardening practice helps reduce compaction in garden soil? Avoid walking on planting beds Minimizing foot traffic protects soil structure and root health. 43.What is an example of a determinate tomato variety trait? Fruits ripen over a short period Determinate tomatoes produce a concentrated harvest, ideal for canning.
44.Which amendment would you add to raise soil pH? Lime Lime is commonly used to make acidic soils more neutral. 45.What is the primary symptom of iron chlorosis? Yellow leaves with green veins This pattern indicates iron deficiency, often in high-pH soils. 46.Which vegetable is a heavy feeder that benefits from rich compost? Corn Corn requires high nitrogen and benefits greatly from nutrient-rich soil. 47.When is the best time to divide most perennials? Early spring or fall Cooler weather reduces transplant shock and supports healthy regrowth. 48.Which of the following trees has opposite leaf arrangement? Maple Maples exhibit opposite branching, unlike many other trees with alternate arrangement. 49.What is one way to prevent tomato hornworms? Hand-pick and destroy them when visible Manual removal is effective and environmentally friendly for home gardens. 50.Why is crop diversity important in sustainable gardening? It reduces pest and disease outbreaks Diverse plantings disrupt pest cycles and promote ecosystem resilience.
58.What is a stolon? A horizontal stem that grows above ground and forms new plants Strawberries spread through stolons, often called runners. 59.Which invasive species is a climbing vine known to smother trees? Kudzu Kudzu grows rapidly and can cover entire trees, blocking light and killing them. 60.What soil property affects water retention the most? Texture Texture (sand, silt, clay) controls how quickly water moves through soil. 61.What is the main benefit of compost tea? It introduces beneficial microbes to soil Compost tea can improve soil biology and plant resistance to disease. 62.When harvesting herbs, when is the best time of day? In the morning after dew has dried This preserves oils and flavor compounds that can dissipate later in the day. 63.What vegetable grows best in cooler soil and will bolt in heat? Lettuce Heat causes lettuce to flower prematurely, turning leaves bitter. 64.What is girdling in trees? Damage around the trunk that cuts off nutrient flow Girdling disrupts vascular tissue, often leading to tree decline or death.
65.What is the function of stomata in leaves? Gas exchange Stomata regulate CO₂ intake and oxygen/water vapor release. 66.Which of the following is a warm-season grass commonly used in Pennsylvania? Zoysiagrass Though less common than cool-season grasses, Zoysia grows well in sunny areas. 67.Which soil type drains fastest? Sandy soil Large particles create big pores, allowing water to drain quickly. 68.Which tree species has exfoliating bark and is native to Pennsylvania? River birch River birch is native, disease-resistant, and valued for its peeling bark. 69.Why is adding too much fertilizer harmful? It can lead to nutrient runoff and plant damage Excess fertilizer can burn roots and harm water quality. 70.What’s the ideal soil moisture level for seed germination? Consistently moist, not soggy Seeds need even moisture to swell and sprout but will rot in saturated soil. 71.What is “thinning” in gardening? Removing excess seedlings to improve spacing Thinning prevents overcrowding and competition for resources.
79.What term describes a plant adapted to dry conditions? Xerophyte Xerophytes store water or reduce loss to survive arid climates. 80.What tool is best for digging holes for transplants? Trowel Trowels are ideal for small, controlled digging tasks. 81.Which plant is often used for erosion control? Crown vetch This groundcover spreads quickly and stabilizes slopes. 82.What is a characteristic of clay soil? Holds water and drains slowly Clay has small particles and poor aeration. 83.What is the primary function of plant roots? Absorb water and nutrients Roots anchor the plant and take in essential resources. 84.Why is staking tomatoes sometimes necessary? To keep fruit off the ground and prevent disease Support improves air circulation and reduces rot. 85.What is the most accurate way to measure rainfall for irrigation planning? Rain gauge A rain gauge gives precise local measurements for managing watering schedules.
86.What is a benefit of raised bed gardening? Improved drainage and soil control Raised beds warm quickly in spring and prevent compaction. 87.Why is pruning important in woody plants? To remove dead or diseased wood and shape growth Proper pruning improves plant health and appearance. 88.Which vegetable is in the Brassica family? Broccoli Brassicas include cabbage, kale, broccoli, and related vegetables. 89.What is leaf scorch often caused by? Lack of water or root damage Leaves dry out when roots can't supply enough moisture. 90.What is the best planting depth for seeds? 2 – 3 times their diameter Planting too deep or shallow can prevent germination. 91.Which practice enhances pollination in gardens? Planting a diversity of flowering plants Diverse bloom times and species attract more pollinators. 92.Which season is best for dividing irises? Late summer Dividing after bloom prevents stress and allows roots to reestablish.
- Which environmental condition speeds up composting? Warm temperatures Heat accelerates microbial activity and decomposition.
- What is a key trait of sandy soil? Low water and nutrient retention Sand drains fast but doesn’t hold resources well.
- What is a cold frame used for? Extending the growing season Cold frames protect plants from frost and allow early planting.
- Which insect pest causes lace-like damage on leaves? Japanese beetles These pests skeletonize leaves and can defoliate plants quickly.
- What is an example of a fungal disease in lawns? Red thread Red thread appears in cool, wet conditions and causes patchy dieback.
- What is meant by “soil tilth”? The physical condition of soil relating to ease of cultivation Good tilth means soil is loose, friable, and aerated.
- Which method is most sustainable for weed control? Mulching and hand-pulling These methods avoid chemical inputs and preserve soil health.
- Which tool is best for edging flower beds? Half-moon edger This sharp tool creates clean, defined bed lines.
- What is the ideal spacing for most tomato plants? 18 – 36 inches apart This spacing allows airflow and light penetration.
- Which insect transmits bacterial wilt to cucumbers? Cucumber beetle They spread the Erwinia bacterium that causes wilt.
- What garden structure can prevent deer damage? Tall fencing (at least 8 feet) Deer are excellent jumpers; short fences are ineffective.
- What is vermicomposting? Composting with worms Red wigglers break down food scraps into nutrient-rich castings.
- What causes fruit cracking in tomatoes? Inconsistent watering Fluctuating moisture levels cause rapid fruit expansion and splitting.
- What is the pH of neutral soil?
_Soil with pH 7 is neither acidic nor alkaline._
- What is the Pennsylvania Department of Agriculture’s plant hardiness zone range?
- What is the life cycle of annual weeds? Germinate, grow, flower, and die in one season Annual weeds must be controlled before they seed.
- What should be avoided in compost piles? Meat and dairy products These attract pests and cause odors.
- What causes leaf curling in tomato plants? Environmental stress or herbicide drift Curling is often a response to temperature, drought, or chemicals.
- Which is the best way to manage slugs organically? Use beer traps or copper barriers These attract or repel slugs without harming other wildlife.
- What is a crown in a perennial plant? The part where roots and shoots meet The crown is critical for regrowth and must not be buried too deep.
- What is a soil amendment? Material added to improve soil quality Amendments change soil structure, pH, or fertility.
- What is a plant’s “hardiness”? Its ability to survive cold temperatures Hardiness zones define cold tolerance for perennials.
- What is a no-till gardening benefit? Preserves soil structure and microorganisms No-till minimizes disturbance and erosion.
- Why is leaf mulch valuable in gardens? It adds organic matter and suppresses weeds Decomposed leaves enrich soil and protect plant roots.
- What is the ideal mulch depth around perennials? 2 to 3 inches Too much mulch can suffocate roots or encourage rot, while too little fails to suppress weeds.
- Which plant is commonly used as a green manure crop in Pennsylvania? Hairy vetch Hairy vetch adds nitrogen and organic matter when tilled into the soil.
- Which flower is known for being deer-resistant? Marigold Marigolds have a strong odor that deters deer and some insects.
- What is the best time to prune spring-flowering shrubs? Immediately after they bloom Pruning too late removes buds that form the next year’s flowers.
