Transcript Greenhouse Management and Crops

Greenhouse Management and
Crops
Section 4
Unit 13, 14, 15
Poinsettias
Unit 13
History
• Poinsettias were grown in Southern
California as cut flowers in 1900
• Today, growing poinsettias is a big part of
many horticultural operations
Greenhouse management
• Factors to consider in greenhouse
production are…
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Temperature
Moisture
Ventilation
Climate
Temperature
• Important to growing a successful crop
• Day temp. should be 5-10 degrees higher
than night temp.
• Thermometers should be at the plant level,
out of direct sunlight to ensure optimum
growth
Moisture
• Plant growth is dependent on moisture
• Influences relative humidity
• Amount of water needed depends on the
type of plant and the outside conditions on a
particular day
• Appearance and feel of the medium is an
indication for watering plants
Ventilations
• Movement and exchange of air in the
greenhouse
• Should be able to feel the air movement in
the greenhouse
• Ensures correct temp and relative humidity
• Helps control plant diseases
Climate
• Directly influences the type of greenhouse
structure, heating and cooling systems
Poinsettia Flower
• Small, yellow flower that grows at the terminal
end of the plant
• Just below the flower are the bracts
– Leaves that give the poinsettias their color
– Most common color is red
• Require a short day for the production of the
flower
• Should be grown in full sunlight
• During months w/ long days, the plants develop
leaves and increase stem length
Growing Poinsettias
• Start from a 2 ¼” rooted poinsettia cutting
– Be sure the plant is healthy
• Plant in pots 4”, 5”, 6” 7” 8” or 10”
• Night temp should be 65 degrees
• Day temp should be 70 – 75 degrees
Pinching
• Process of removing the terminal end of the plant
• Accomplished by taking the top of the plant
between the thumb and index finger and carefully
breaking the top of the poinsettia completely off
• 4-5 leaves should remain on the plant
• After pinching, new shoots called breaks will
develop from the bud in the axis of the node
– Each shoot will produce a flower
• Main reason for pinching is to increase the number
of bracts per plant
Soil Mixes
• May be grown in many different media
• Must be porous and well-drained
• Should be free of insects and disease
organisms
• Should have good nutrient-holding
capabilities
• Soil can be sterilized at 180 degrees for 30
minutes
Fertility
• Fertilizer should be complete
– Contain nitrogen, phosphorus, and potassium
• Follow manufacturer’s recommendations
for application
Growth regulators
• Growth regulators have 2 main purposes
– Control the height of the plant
– Improve quality of color in bracts
• Applied as a soil drench or foliar spray
• Examples:
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Cycocel
Ancymidol
Bonzi
B-nine
• Height can be controlled to some extent by
adjusting light level and durations and by
regulating day and night temps
– Brighter light results in more compact plants
– Shorten plants by lower daytime than nighttime
temp
Maintaining Poinsettias
• Handle new plants carefully
• Protect from insects using chemical
pesticides
• Protect from attack by disease organisms
– Clean poinsettias must be purchased
– Clean growing media must be used
– Treat w/ fungicide when transplanted
Chrysanthemums
Unit 14
Chrysanthemums
• The most popular cut flower sold in the US
• Because of artificial control of day and
night in the greenhouse, they can be grown
throughout the entire year
• Most popular on Mother’s Day, Easter, and
Memorial Day
Determining market and variety
• Schedule planting so that plants bloom at
desired time
• Some varieties bloom in 8 weeks after the
start of short days, others 10, 12, or 14
weeks
• This is known as response time
– Chrysanthemums are cataloged by their
response time
Regulating Light
• Mums are a short-season crop
– Sets flower buds and blooms only when nights
are long and days are short
• Control light when…
– Rooted cuttings are 1st potted – days kept long
and nights short (7 hrs of darkness max)
– Summer flowering is desired, days kept short
and nights long to encourage proper timing of
flower bud formation
Obtaining Starter Plants
• Propagated by softwood cuttings
• Diseases may be passed along from parent
plants
• Very important to purchase rooted cuttings
from disease free retailers
Establishing a growing schedule
• A growing schedule must be established
before ordering rooted cuttings
• Start at the end of the schedule (the
blooming date)
• Control day and night lengths to follow the
schedule
Planted rooted cuttings
• 6-inch plastic pot is a good choice for planting
rooted mum cuttings
– Requires 5 cuttings per pot
• Well drained medium that holds moisture well
• Water added to the medium should quickly drain
to the bottom of the pot
• Don’t let the potted cuttings dry out
– Provide a constantly moist, but not wet soil
– Add water when the top of the potting medium 1st
appears to be drying out
Caring for Potted Cuttings
• Greenhouse temp should be @ 63 degrees at night
when 1st placed in the growing area
• Higher temps promote faster vegetative growth
• If temp drops below 60 degrees flower buds may
not set evenly
• Temps are dropped to 62 degrees and then to 55
degrees for the last 3 weeks
– Cooler temp tends to harden off the plants
Fertilizing cuttings
• Constant application of fertilizer
– Diluted fertilizer may be added to the irrigation water
• Slow release fertilization
– Mixed in the potting medium at the time of planting
• Timed applications
– Apply once every 2-3 weeks in irrigation or to the pot
as needed
Watering
• Frequency varies w/ temperature and humidity and
water holding capacity of the medium
• Hot & Dry weather, twice a day
• Other times, once a day or every other day
• Check soil frequently and add water whenever top
of medium is beginning to appear dry
• Do not keep soil saturated
Pinching and Disbudding
• Pinch off ¼ to ½” of stem growth
– Causes shoots to develop resulting in more
branches
• Ideal mum should have about 10-15 flowers
per pot
Growth Retardants
• Similar to Poinsettias
• Controlling insects and disease
• Good sanitation and cultural practices often
all the control needed