Plant nursery Study Guide

📖 Core Concepts Nursery – a site where plants are propagated and grown to a usable size for gardening, forestry, or conservation. Primary Functions – produce planting stock for retail, wholesale, private estates, or institutional use. Nursery Types – Retail (direct to public), Wholesale (large‑quantity sales to other growers), Private (supplies institutions/estates), Specialty (focus on a single plant group). Propagation Techniques – seed, cuttings (shoot tips or roots), tissue culture, grafting/budding, division. Plant Material Forms – rooted cuttings, unrooted cuttings, plugs, bare‑root plants. Growing Environments – open field, containers, tunnels, greenhouses. Conditioning – treatments that improve seedling stress tolerance before out‑planting (e.g., hardening off). Planting Stock Quality – “fitness for purpose”; assessed by morphology (height, root‑collar diameter, shoot‑to‑root ratio) and physiological tests (e.g., frost hardiness, RGC). Classification – age system (e.g., 2+0), description codes (height, stem diameter, shoot‑to‑root ratio), and product forms (bare‑root, container, ball‑and‑burlap). 📌 Must Remember Slope guideline: optimal nursery slope = 1–2°, >5° → high erosion risk. Row orientation: rows run across the slope to reduce runoff. Drainage test interpretation: water‑level drop ≤ 0.5 in = poor; 0.5–1 in = medium; > 1 in = rapid drainage. Frost hardiness (LT₅₀): –15 °C = ready for outdoor planting in Ontario; –40 °C = suitable for frozen storage. Irrigation systems: drip and overhead are the common types. Fertilizer effects: high fertility → more shoot growth, less root growth → top‑heavy seedlings. Nutrient storage: N does not build up; P and K can accumulate long‑term. Stock size: larger seedlings generally give greater stem volume & height after 10 yr, especially under competition. Bare‑root definition: plant sold without soil; marketed in winter for spring planting. Ball‑and‑burlap root loss: up to 90 % of roots may be lost during excavation. Root‑bound cause: roots grow in circles inside containers. Air‑pruning: exposure to air stops root tip elongation, preventing circling. 🔄 Key Processes Soil Drainage Test Dig a hole, fill with water, let stand 30 min. Measure drop in water level: ≤0.5 in → poor; 0.5–1 in → medium; > 1 in → rapid. Hardening Off (Conifers) Wait until terminal buds have formed and stem & root growth have ceased. Expose seedlings gradually to lower temperatures; monitor LT₅₀. Fertilizer Application (Forest Tree Nurseries) Apply N, P, K regularly; add Ca & Mg occasionally. Watch for excessive N → shoot‑dominant growth. Root Pruning (Mechanical) Attach “U”‑shaped or linear blades to tractor, pass over beds to cut excess roots. Air‑Pruning Container Use Plant in containers with built‑in air holes; roots reaching a hole are exposed to air and stop elongating, stimulating lateral branching. 🔍 Key Comparisons Retail vs. Wholesale vs. Private vs. Specialty Retail → sells directly to public. Wholesale → sells bulk to other growers/landscapers. Private → supplies a single institution/estate. Specialty → focuses on one plant type (e.g., shade plants). Bare‑Root vs. Container vs. Ball‑and‑Burlap Bare‑root: no soil, winter market, requires careful handling of roots. Container: plant stays in pot; easier handling, higher root‑bound risk. Ball‑and‑burlap: soil retained, but up to 90 % root loss during lift. Hardening vs. Non‑Hardening Seedlings Hardened: terminal buds formed, growth stopped, higher frost tolerance. Non‑hardened: still actively growing, lower LT₅₀. Air‑Pruning vs. Mechanical Root Pruning Air‑pruning relies on exposure to air; promotes finer root systems. Mechanical uses blades; quickly cuts excess roots in field operations. ⚠️ Common Misunderstandings “Bigger always better.” Large stock performs better under competition, but excess shoot growth can cause top‑heavy, unstable seedlings. RGC = field success. Root Growth Capacity tests are useful but unstandardized; correlation with field performance varies. All fertilizer improves growth. Over‑fertilization (especially N) skews shoot/root balance. Steep slopes are fine if irrigation works. Slopes >5° dramatically raise erosion risk regardless of water management. LT₅₀ = the temperature seedlings can survive indefinitely. LT₅₀ is the temperature at which 50 % of seedlings die; survival improves with acclimation. 🧠 Mental Models / Intuition Nursery as a “factory line.” Think of each stage (propagation → conditioning → quality test → market form) as a production step; bottlenecks (e.g., poor drainage) affect the whole line. Fitness‑for‑purpose = right tool for the job. Choose stock size, form, and conditioning based on the target site’s stressors (competition, frost, moisture). Slope = water’s highway. Small slopes let water flow gently; steep slopes turn it into a torrent that washes soil away. 🚩 Exceptions & Edge Cases High fertility side‑effect: can create seedlings that look vigorous but are root‑weak. Nitrogen storage: unlike P & K, N does not accumulate; repeated N applications may be needed. Frost hardiness thresholds: –15 °C is adequate for Ontario field planting only for species with that LT₅₀; colder‑hardy species may still need –20 °C or lower. Root‑ball sizing: must follow species‑specific caliper rules; a generic “large ball” may still be insufficient for deep‑rooted trees. 📍 When to Use Which Market form: Use bare‑root for winter‑season planting of perennials and woody plants where low cost and easy transport are priorities. Choose container when rapid transplant and reduced root‑bound risk are needed (e.g., retail sales). Opt for ball‑and‑burlap for large trees where maintaining a soil envelope is critical despite some root loss. Propagation method: Cuttings (shoot tip or root) → fast, clones of elite genotypes; best for species that root easily. Seeds → genetic diversity; necessary for species that do not root readily from cuttings. Tissue culture → mass propagation of disease‑free material; high cost, used for high‑value or difficult‑to‑root species. Irrigation: Drip → water‑efficient, ideal for container or row crops on gentle slopes. Overhead → useful for large open fields where uniform coverage is needed and slope is low. Fertilizer strategy: Apply N regularly for shoot growth, but monitor root/shoot ratio; add P and K for long‑term soil buildup. Add Ca/Mg only when soil tests show deficiencies. 👀 Patterns to Recognize Erosion risk pattern: slope > 5° + rows parallel to slope → high runoff & soil loss. Moisture‑related mortality: seedling moisture content > 20 % in cold storage → poor post‑plant survival. Shoot‑to‑root ratio > 2:1 → likely top‑heavy, poor field stability. Rapid drainage (drop > 1 in) → well‑drained soils; may need more frequent irrigation. 🗂️ Exam Traps LT₅₀ confusion: choosing –15 °C as “the lowest temperature a seedling can survive” ignores that it’s a 50 % mortality point, not a guarantee of survival. Drainage test misreading: assuming any drop > 0.5 in is “good”; the test distinguishes medium vs rapid, each with different management implications. RGC over‑reliance: selecting seedlings solely on high RGC scores can miss other vigor factors (e.g., root architecture). Fertilizer assumption: believing that adding more N always improves stock; excess N can create shoot‑dominant, weak‑rooted seedlings. Age classification misinterpretation: reading “2+0” as “two years total” without recognizing it means 2 years in seedbed + 0 transplants. --- Study tip: Review each heading, quiz yourself on the bullet points, and practice applying the decision rules to sample scenarios. Good luck!