Download 4.00 Greenhouse Management

UNDERSTAND GREENHOUSE
MANAGEMENT
4.02 Understand greenhouse structures, production,
and maintenance.
Purposes of Greenhouses
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The “greenhouse effect” collects and stores heat
from the sun or radiant heat.
Provides a protective environment to grow plants.
Many detached houses can be used as connected
houses.
Detached Houses-Quonset
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Curved (half-moon) roof bars
Covered with plastic or fiberglass panels
Detached Houses-Lean to
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Roof slopes in one direction only
Built against other greenhouses or buildings
Generally faces south
Detached Houses-Even Span
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Roof is equal in width and pitch on both sides
Most commonly used as a single greenhouse
Clear span, truss support, no columns
Detached Houses-Uneven Span
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One side of the roof is
longer than the other side
for southern exposure.
Usually found on hillsides
with one wall.
May have a solid north
wall.
Advantages of Detached Houses
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Easy to program and maintain temperature
Easy to ventilate without exposing the plants to
blasts of cold air
Disadvantages of Detached Houses
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Requires more energy to heat and cool
Higher initial cost
Connected Houses-Ridge and Furrow
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Even span structures placed one after the other
No side walls
Connected Houses-Barrel Vault
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Quonset houses set on sidewalls
Height of sidewall ranges from 7’-10’ depends on
crops
Connected Houses-Dutch-venlo
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Ridge and furrow construction
Highest percentage of light transmission
Connected Houses-Saran-Covered
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Used to reduce the
intensity of bright sunlight
in frost-free areas
Mainly used for florist
crops
Advantages of Connected Houses
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Requires less land area
Less construction materials
Heat loss is less
Disadvantages of Connected Houses
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Snow build-up in
connecting gutters
Gutters shade parts of
the greenhouse
Greenhouse Equipment and Controls
Temperature Control
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Heaters-gas or electric
Thermostats-controls the temperature and should be
at plant level
Evaporative Cooling Systems
 Most
effective method for cooling a greenhouse
 Constructed of thick corrugated cardboard
 Reduces watering due to higher humidity created by
evaporation from the dripping water in the cool pad
Temperature Control
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Exhaust fans-pulls hot air from the greenhouse
Vents-located at the opposite end from the exhaust
fan. Vents open to allow fresh air in the
greenhouse.
Circulation Fans-circulates air in the greenhouse
even when the exhaust fan is not running. Provides
a uniform temperature throughout the greenhouse.
Timers
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Timers should be used to control lights, shade cloth,
irrigation, etc.
Irrigation
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Misting system-cools the greenhouse and provides a
fine mist for seeds and cuttings
Overhead irrigation system-waters greenhouses or
shadehouses but may not give deep watering some
plants need
Drip irrigation-tubes with emitters go to individual
pot for water. A very efficient way to water.
Lights
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Provide additional lighting for plants on cloudy or
wintery days. To block out light for certain crops in
the greenhouse use black cloth.
Greenhouse Coverings
Greenhouse Film (polyethylene film)
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3-6 mil thick
Standard to UV treated. UV film keeps ultra violet
rays from damaging plants
Inexpensive
Long lasting and easy to replace
Acrylic Panels
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Energy efficient
Impact resistant
Available in a variety of widths and lengths
Polycarbonate Panels
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Twin wall panels
Corrugated panels
Available in a variety of widths and lengths
Relatively expensive
Solexx Panels
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Flexible
Twin wall
3-6 mil thick
Opaque
Relatively expensive
Greenhouse Plant Terminology
Life Cycles
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Annual-plants that complete their life cycles in one
year
Biennial-Plants that complete their life cycles in two
years
Perennial-plants that live more than two years
Planting Methods
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Sow-to plant seeds
 Direct
sowing-starting seeds directly into the soil or
pots. No transplanting necessary.
 Indirect sowing-starting seeds in flats, trays, etc. and
transplanting them into the soil or other pots.
Plant Manipulation
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Deadheading-removal of spent or dead flowers
Pinch-removal of the top portion of a plant to make
the plant more compact
Light Requirements
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Full sun-requires at least 6 hours of sun each day
Part shade-morning sun until 12:00 noon, no
afternoon sun
Shade-a few hours of morning sun, filtered light or
full shade
Bedding Plant Soils/Media
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Vermiculite-expanded mica, sterile
Perlite-expanded volcanic rock
Peat moss-decomposing parts of sphagnum moss
typically found deep in bogs
Sand-finely ground stone
Bark-tree bark usually shredded or ground
Commercially prepared soil mixes usually contain
peat moss, perlite and vermiculite and are sterile,
weed, insect and disease free
Containers
Flats/Cell Packs
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Flat-Plastic tray usually for planting seeds or
holding cell packs. 10”Wx20”Lx2 ½”D (may vary
in size)
Cell pack-several small cell like pots of plastic
molded together. Four common sizes are 804, 606,
1206, 1801
Natural Pots
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Peat Pots-insulate the roots, can be planted directly
into the soil, breaks down when planted, roots grow
through peat material.
Eco pots-expensive, made from plants and
vegetable oil
Jiffy 7-compressed peat moss covered in fine mesh.
They expand when soaked in water and can be
planted directly into the soil. Can be used for
sowing seeds or rooting cuttings.
Plastic Pots
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Standard pot is the same width at the top as it is
high.
Azalea pot is ¾ as high as its top diameter or
width.
Vary in sizes and shapes.
Clay Pots
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Made of porous materials
Can be glazed
Various sizes and shapes available
Hanging Baskets
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Plastic, wire, cloth pouches (living walls)
Wire hanging baskets may require some type of
liner
Varies in sizes 8”, 10”, 12”, 16”, etc.
Greenhouse Production
Greenhouse Production from Seeds
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Select seeds to sow. Read specific instructions for
selected seeds.
Sow selected seeds in a sterile seed starter media.
Cover if necessary.
Water seeds from the bottom or mist.
Cover seeds with a humidity dome (if necessary).
Place seed flat on the bench in the appropriate
light and/or on propagation mats if needed.
Check seeds daily for moisture.
Greenhouse Production from Seeds
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Once seeds germinate and true leaves (2nd set of
leaves) appear, prepare to transplant.
Loosen media to prevent breaking roots and stems
of seedlings.
Hold plants by their leaves. Do not hold the stem
as they bruise easily.
Transplant seedlings into saleable containers
slightly deeper than it grew in the flat. (Tomato
seedlings-plant to the bottom of the true leaves.)
Greenhouse Production from Seeds
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Water newly transplanted seedlings.
Provide the appropriate light for the plants
Create a pest free environment and/or control
pests as needed.
Harden off (drop the temperature and reduce
water) before moving plants out to shade houses
or protected area.
Greenhouse Production from Cuttings
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Select plants for cuttings (English Ivy, pothos,
wandering jew, etc.)
Make cuts below the node (area on the stem
where leaves grow), remove leaves (if necessary),
dip in water and dip in rooting hormone, tap
lightly.
Make a hole in the sterile soil
Stick cutting(s) into the hole.
Gently push soil around cutting
Greenhouse Production from Cuttings
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Water the cuttings.
Place under greenhouse benches for a couple of
days to lessen shock.
Grow in a sunny location in the greenhouse.
Bedding Plant Problems
Cultural Disorders
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Seed germination problems
 Improper
temperatures
 Over-watering or under-watering
 Chemical residues in soil
 Seed planting depth
 Low quality seeds
Cultural Disorders
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Seed germination solutions
 Maintaining
proper temperature
 Maintain proper moisture levels
 Chemical free soil
 Plant at proper depth
 Use high quality seeds
Cultural Disorders
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Fertilization problems
 Lack
of nutrients
 Root injury
 Improper pH in soil
 Excessive fertilization
Cultural Disorders
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Fertilization solutions
 Testing
soil
 Applying correct amount and kinds of nutrients
 Correct pH
Cultural Disorders
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Uneven growth problems
 Poor
mixing of soil
 Uneven moisture levels
 Unlevel flats
 Uneven bottom heat
 Poor grading of seedlings
Cultural Disorders
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Uneven growth solutions
 Properly
mixing soil
 Even watering
 Placing flats level
 Replace damaged propagation mats or cables
 Grading seedlings by size
Cultural Disorders
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Tall and spindly growth problems
 Too
much nitrogen fertilizer
 Overwatering
 Low light intensity
 High temperatures
Cultural Disorders
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Tall and spindly growth solutions
 Use
the correct amount of nitrogen
 Reducing frequency of watering
 Lowering temperature
 Provide more light
 Use a growth retardant such as B-Nine
Diseases
Disease Problems
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Damping off-seedlings fall over causing the stem to
rot
Disease Problems
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Botrytis-lower leaves are brown, rotting and drying
out
Disease Solutions
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Use sterilized soil
Use fungicides to control diseases
Improve air circulation
Increase air temperature around plants
Pests-Problems and Solutions
General Pest Problems
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Plants or seedlings missing caused by slugs, snails, or
roaches
Holes in the leaves, damaged leaves or missing
plant parts
General Pest Solutions
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Monitor plants on a regular basis for insect
problems.
Identify pests
Use beneficial insects-parasitic wasps, ladybeetles,
praying mantis or lacewings
Use an insecticide
Types of Pests
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Aphids
 Green
soft bodied, winged or non-winged, sucking
insect
 Control using ladybeetles, praying mantis, insecticidal
soap
Types of Pests
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Mealybugs
 White,
cottony, sucking insect
 Control using insecticidal soap
Types of Pests
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Spider Mites
 Red
body pest with eight legs
 Control using predatory mites and miticides
Types of Pests
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Scale
 Brown,
hard shelled, sucking insect
 Outdoors control using dormant oil. Greenhouse control
using alcohol on individual insects or insecticidal soap.
Types of Pests
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Thrip
 Small
translucent, sucking insect
 Control using parasitic wasps and insecticidal soap
Types of Pests
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Whiteflies
 Powdery
insects with four white wings, sucking insect
 Control using a whitefly trap (sticky board) or
insecticidal soap
Types of Pests
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Fungus gnats
 Thrive
in moist wet environments
 Larva feed on plant roots and new callused tissue
 Control by watching moisture levels in the greenhouse
and use of biological control such as Bacillus
thuringiensis
Types of Pests
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Leaf miner
 Larva
produces mines by burrowing and feeding
between the upper and lower epidermis of leaves. This
allows air in and changes the leaf color in the mines to
pale green or silver.
 Control using pyrethroid (attacks the exoskeleton of the
insect)
Types of Pests
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Cutworms
 Can
enter the greenhouse as moths and lay eggs.
 Cutworms chew at the soil level
 Control using Bacillius thuringiensis
Types of Pests
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Slugs
 2”-3”
slimy brown body, burrowing pests, damage roots
and leaves of plants
 Control using slug trap or hand pick
Types of pests
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Caterpillars
 Eat
plant parts, chewing insects
 Control using Bacillius thuringiensis
Greenhouse Maintenance
Structure Maintenance
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Painting wood (rot) and metal (rust) structures as
needed
Flooring (gravel, wood, cracked concrete) replaced
as needed
Doors (steel, wood, metal) repaired as needed
Replace Covering
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Replace glass when cracked or broken
Replace fiberglass when damaged
Replace greenhouse film (polyethylene) when torn
or damaged
Cover or take off shade cloth depending on season
Equipment Repair
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Heater-motor, fan blades, gas/electric lines, etc.
Ventilation system-belts, motor, etc.
Irrigation-clogged emitters, holes in tubing
Lighting-electrical, bulbs
Pest Control
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Set up a maintenance schedule for weed, insect,
and disease control.
Plant Maintenance
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Water plants regularly, avoid watering in the
middle of the day during the summer.
Set up a fertilizer schedule
Check for insects and diseases and treat
appropriately
Control weeds
Pinch plants to encourage fullness if necessary
Keep the greenhouse clean