Greenhouse and Nursery Production —HORT Crop Prod Lecture 1

Greenhouse and Nursery Production — Comprehensive Study Notes

  • Overview and context

    • The session emphasizes ornamental horticulture and its major sectors, with a focus on greenhouse production (under glass) and nursery production (field-based). The host asks students to reflect on personal experiences with plants (nurseries, flowers, rooftop gardens, home gardens) to connect theory with real-world practice.
    • Key terms:
    • Ornamental horticulture: the cultivation of flowering and foliage plants for aesthetic use in landscapes, interiors, and outdoor spaces.
    • The five main sectors highlighted:
      • Flowering culture: cut flowers, greenhouse-grown flowering plants, and nursery production of flowering ornamentals.
      • Nursery production: growing larger plants (shrubs, trees) for eventual sale.
      • Landscaping: design and maintenance of outdoor spaces as a business and art.
      • Interior space horticulture: using plants indoors in offices, malls, and indoor environments.
      • Turf grass management: lawns, golf courses, and athletic fields.
    • Today's emphasis: greenhouse production and nursery production (greenhouse vs field) and how these systems operate, plus sustainable management and propagation approaches.

  • Road map and learning goals

    • Three-part roadmap:
      1) Greenhouse production (world under glass): understanding controlled-environment production.
      2) Field/nursery production: outdoor, ground-level production.
      3) The starting point for everything: foundational concepts in propagation and management.
    • Learning outcomes:
    • Compare and contrast greenhouse production with nursery (field) production.
    • Identify the key factors growers control inside the greenhouse.
    • Describe the principle of sustainable nursery management.
    • Understand the main methods of propagation (sexual vs vegetative) to prepare for the lab.

  • Greenhouse production (under glass)

    • Definition and purpose
    • Greenhouse production is the practice of growing plants inside a structure where temperature, light, water, and other conditions are controllable to achieve high-quality crops year-round.
    • The keyword: control everything to grow high-quality material all year round.
    • Typical crops and settings
    • Plants grown in containers or bedding plants and perennials, as well as some vegetables and herbs.
    • Examples: poinsettia (a major container crop for the holiday season).
    • Local Alabama example mentioned: Dixie Green, a farm known for greenhouse/crop cultivation (illustrative example of a successful operation).
    • What the greenhouse enables
    • Uniform crops and year-round production through environmental control.
    • Focus areas within greenhouse production
    • Light, temperature, carbon dioxide (CO₂), and water/nutrient management are the core controllable factors.

  • Light: intensity and photoperiod

    • Key concepts
    • Light intensity is quantified by the Daily Light Integral (DLI).
      • Definition: DLI measures the total amount of light (photosynthetically active radiation) received over a day; higher DLI generally promotes stronger growth, more branching, and more flowers.
      • A representative (conceptual) equation: ext{DLI} riangleq rac{PPFD imes ext{photoperiod}}{1000} ext{ mol m}^{-2} ext{d}^{-1} where PPFD is photosynthetic photon flux density.
    • Photoperiodism: the duration of light exposure (how long the lights stay on) affects flowering and growth; plants can be short-day or long-day, responding to day length.
    • Practical implications
    • Short-day plants (e.g., mums) require long nights to flower; long-day plants require longer days.
    • Growers manipulate light to induce flowering on command (e.g., bloom timing for market windows).
    • Classroom example and discussion
    • A quick pair activity discussed how to bloom mums in spring and pulsatillas for Christmas by controlling light (extending or shortening dark periods).
    • A common greenhouse trick mentioned: using blackout fabrics or curtains to create extended dark periods, enabling off-season blooming (e.g., Christmas cactus dark treatment a month before desired bloom).

  • Temperature control and DIF

    • Temperature as a controllable factor
    • Greenhouses use ventilation, heating, fogging, and insulation to maintain optimal temperatures.
    • DIF concept
    • DIF = Day temperature − Night temperature.
    • Positive DIF: warm days and cooler nights promote more robust growth and plant height.
    • Negative DIF: cooler days and warmer nights promote shorter, more compact plants.
    • Practical use: growers adjust DIF to control plant height without resorting to chemical plant growth regulators (PGRs).
    • PGR note
    • Plant growth regulators (PGRs) are commonly used in the industry, but DIF provides a cost-effective, non-chemical alternative to height control.
    • Illustrative example from the lecture
    • A comparison between plants with positive DIF (e.g., warm days, cool nights) and a control plant at a standard temperature (e.g., 20°C) shows that positive DIF results in taller growth, while negative DIF yields a shorter, more compact plant.

  • CO₂ enrichment

    • Why CO₂ enrichment matters
    • Greenhouses are closed environments; CO₂ is often a limiting resource for photosynthesis, so enriching CO₂ can improve growth and yield.
    • Methods of CO₂ delivery
    • Dry ice (solid CO₂), liquid CO₂, CO₂ tanks, CO₂ generators (burning natural gas).
    • Distribution and safety
    • CO₂ is heavier than air, so it must be distributed using circulating fans or other delivery systems to ensure even mixing and prevent pockets of high concentration.
    • Practical note
    • CO₂ enrichment is an additional operational factor that must be managed with the other environmental controls in a greenhouse.

  • Water and nutrients (the plant’s diet)

    • Core idea
    • Water quality and delivery method are critical; plants need a balanced nutrient supply delivered at the right time according to growth stage.
    • Water quality and irrigation
    • Water quality (pH) must be monitored because extreme pH values hinder nutrient uptake even if nutrients are present.
    • Efficient irrigation methods to conserve water and keep leaves dry include:
      • Drip irrigation
      • Sub-irrigation (ebb and flood or trough systems)
      • Capillary mats
      • Overhead irrigation (less preferred for leaf-dryness concerns)
    • Practical note: water should be applied thoroughly but only when the plant actually needs it; overwatering or underwatering can both cause stress.
    • Indicator of need: wilt or droop (flagging) signals that a plant needs water.
    • Nutrient management
    • Plants require 17 essential nutrients; primary macronutrients (N, P, K) are the most crucial for growth.
      • Nitrogen (N): leafy growth and green coloration.
      • Phosphorus (P): strong root and flowering development.
      • Potassium (K): overall plant health and vigor.
    • Secondary macronutrients and micronutrients
      • Secondary: Calcium (Ca), Magnesium (Mg), Sulfur (S) — important for various physiological processes and structural integrity.
      • Micronutrients: Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Boron (B), Molybdenum (Mo), Chlorine (Cl), and other trace elements.
    • Fertilizers and application methods
      • Complete fertilizers contain N, P, and K plus essential micronutrients; often used in soluble form via fertigation (mixed in irrigation water).
      • Incomplete fertilizers deliver only a subset of nutrients at specific growth stages.
      • Fertigation describes delivering soluble fertilizers through irrigation systems (e.g., drip systems).
      • Insoluble fertilizers include slow-release and controlled-release fertilizers, used to reduce runoff and provide steady nutrient supply, especially important in regions with heavy rainfall (e.g., Alabama).
      • Fertilizer labeling example: common N-P-K notation such as N−P−K=10−10−10N-P-K = 10-10-10.
    • Water and nutrient planning in practice
    • A balanced diet is essential; nutrients are timed to growth stages (seedling, vegetative, flowering, fruiting).
    • pH management is crucial for nutrient availability; certain nutrients become unavailable if pH strays too far from optimal ranges.
    • Lab and measurement notes mentioned
    • A pitch reader (for measuring substrate or water characteristics) demonstration is planned with Dr. Matthew Wilson on Sept 17, to measure pH/potentials in the greenhouse environment.

  • The “superpower” of greenhouse management

    • Quick interactive takeaway
    • The most powerful tool for a greenhouse grower is the ability to control the environment (light, temperature, CO₂, water, nutrients).
    • Case-based practice
    • Case 1 (April flowering for Mother’s Day): To ensure a short-day plant like mums blooms by May, extend the dark period using blackout materials to simulate longer nights.
    • Case 2 (tomato transplants growing too tall): Shorten the day-night temperature difference (DIF) to around 10°C or less to promote compact growth (negative or smaller positive DIF depending on baseline). The key concept is that reducing DIF helps reduce height without chemical PGRs.

  • Nursery production (field-based)

    • General concept
    • Nursery production involves large-scale production of trees, shrubs, and perennials for landscaping and street planting, typically in open fields.
    • Field-grown vs other nursery methods
    • Three ways to grow plants in the nursery are mentioned, with field-grown being the first method described.
    • Field-grown plants are often sold with a burlap root ball (ball-and-burlap system) for easier transport and establishment in new locations.
    • The speaker notes this is labor-intensive and illustrates a real-world example (an 8-foot-tall plant in Louisiana in 2019).
    • Practical implications
    • Field production is suitable for large trees and shrubs but requires significant labor and space; handling and transplanting follow specific burlap-ball protocols.
    • Note on missing details
    • The transcript mentions three methods but only details field-grown (ball/burlap) explicitly; other methods are not described in the provided content.

  • Lab, field lab, and upcoming industry insights

    • The class plans a greenhouse lab session on a Wednesday.
    • Guest and industry leaders
    • Greg Langston and Russell will join to discuss trends and current industry practices.
    • They are described as leaders in the Family Farm Association and Food Association, as well as the Nursing Ascension Association in Alabama (note: these associations are mentioned in the transcript and are presented here as part of the context for industry connections).
    • Purpose of the industry guest session
    • To share current trends in the industries and connect classroom concepts with real-world practices and networks.
    • Logistics mentioned
    • The class will share a map to Patterson Greenhouse via Canvas, with a note about parking and walking through the greenhouse.

  • Quick recap: connecting theory to practice

    • Greenhouse production emphasizes the power of environmental control to achieve year-round, high-quality plant production.
    • The main levers of control are light, temperature, CO₂, and water/nutrient management.
    • Understanding DIF and DLI helps optimize plant height, flowering, and overall vigor without relying solely on chemical growth regulators.
    • Fertigation and fertilizer management (complete vs incomplete vs slow-release) are essential for efficient nutrient delivery and environmental stewardship.
    • Field/nursery production complements greenhouse work by addressing large-scale propagation and establishment, particularly for trees and shrubs.
    • Real-world connections (industry partners and field trips) help contextualize classroom learning and prepare students for lab activities.

  • Foundational formulas and concepts to remember

    • DIF: extDIF=T<em>extday−T</em>extnightext{DIF} = T<em>{ ext{day}} - T</em>{ ext{night}}
    • DLI (conceptual): ext{DLI} = rac{PPFD imes ext{photoperiod}}{1000} ext{ mol m}^{-2} ext{d}^{-1}
    • N-P-K notation on fertilizers (example): N−P−K=10−10−10N-P-K = 10-10-10

  • Practical implications for exam preparation

    • Be able to define greenhouse production and list the major controllable factors (light, temperature, CO₂, water/nutrients).
    • Explain the concepts of DIF and DLI and how they influence plant height and flowering.
    • Describe the differences between complete and incomplete fertilizers, and the role of fertigation and slow-release fertilizers.
    • Understand the practical steps a grower might take to manipulate flowering times (e.g., blackout for mothers’ day mums) and to control plant height (DIF management).
    • Recognize the differences between greenhouse and field/nursery production and the typical crops involved in each.
    • Appreciate the role of sustainability in nursery management, such as water conservation, efficient irrigation, and nutrient management to minimize runoff and environmental impact.

  • Ethical, philosophical, and practical implications

    • Sustainable management emphasizes minimizing chemical inputs and maximizing energy and water efficiency in controlled environments.
    • CO₂ enrichment has productivity benefits but requires careful monitoring and safety considerations in enclosed spaces.
    • The move toward precision agriculture (paced by measurements like soil pH, pitch readings, and real-time environmental data) supports more responsible use of resources.
    • Industry partnerships and lab experiences bridge classroom learning with real-world practices, fostering responsible professionals who understand both economic and environmental factors in horticulture.