Horticulture 1

Welcome, Horticulture Students!

Practical Horticulture

Horticulture is Hands-on…

You are an important part of this class.

Your classmates and your plants will depend on you for crop production and maintenance.

There may also be opportunities for community service credits and internships.

Your Homework For Monday

v  Read Chapter 1 of “Practical Horticulture” and answer questions 1-7 on page 15.

v  Either copy the questions or write answers that let me know what the questions are (turn the questions around.)

v  Be sure to write the chapter number, date, and your first and last name on each homework assignment.

For Wednesday v  Read pages 16-21 in chapter

2, ending before getting to “Plant Anatomy.” Answer questions 1-5 on page 31.

v  Quiz 1 on Blackboard Due.

Keeping It Clean in the Greenhouse

Keeping It Clean v  Greenhouse benches are like the countertops in the kitchen.

They need to be kept sanitized to prevent plant contamination. Chlorine bleach mixed to a 10 percent solution and allowed to stand for five minutes is very effective at killing disease pathogens. It’s toxic. Use gloves and prevent spills.

v  Check beneath your feet. The floor is a big source of disease pathogens and insects. Landscape fabric harbors critters, and greenhouse pathogens can survive a long time in the soil. Cement and gravel floors are less problematic.

v  Bringing in plants. Do not bring plants into the greenhouse, or at least not until they are properly quarantined and checked for insects and disease.

Keep Tools & Equipment Clean

v  Growers who use soilless mixes spend a lot of money when purchasing bags of mix. However, they often use unsterilized tools in the mix, pour the mix on unclean surfaces, or use pots or trays that are contaminated from last year.

v  It is particularly important to disinfect tools after taking plant cuttings. Viruses and bacteria are easily spread between plants. You can use a 10% bleach solution.

v  Establish a culture for clean. The most efficient and productive greenhouse operations have a protocol they follow for keeping the greenhouse as spiffy as possible.

v  Part of this protocol, besides keeping tools and equipment clean is to disinfect benches after each crop, and disinfecting pots before reuse.

The Poinsettia v  Native to southern Mexico and northern Guatemala around Taxco

Mexico (25 miles south of Mexico City)

v  Cultivated by the Aztecs in Mexico; flowers considered a symbol of purity

v  In the 17th century, Franciscan priests settled near Taxco began using in holiday celebrations because it was one of the few plants in bloom around Christmas

v  First introduced to the U.S. in 1825 by Joel Robert Poinsett, first U.S. ambassador to Mexico

v  In 1902, Albert Ecke arrived in the U.S. from Germany and began growing poinsettias as field-grown cut flowers in California

v  In the 1920s and 1930s, poinsettias become the sole enterprise of the Ecke family and the family name to this day is synonymous with the poinsettia in the U.S. After 100 years, the family finally sold the business.

cyanthium à

Seedling cultivar ‘Oak Leaf,’ the progenitor of modern poinsettia cultivars.

Joel Roberts Poinsett (1779-1851)

Cultivars (Cultivated Varieties) include ‘Prestige Red’ and ‘Polar Bear’

Scientific Name: Euphorbia pulcherrima

Plant Family: Euphorbiaceae

Common Name: “poinsettia”

v  The 50+ commercial cultivars grown before 1960 were sports selected from large numbers of seedlings.

v  Breeding is targeted for color, shorter height, sturdiness, foliage retention, longer lasting color, ability to produce many blooms from one pinch

v  Red is the most widely grown flower color, followed by pink, white, and various bicolor combinations of red and white, or pink and white. One yellow-flowered cultivar (‘Lemon Drop’) is available.

The Flower

Conspicuous parts of the flower are modified leaves called bracts. The actual flowers are located in the center at the base of the bracts. The flower forms are known as cyathia (singular, cyathium) and occur in separate male and female forms. One standard way to tell when poinsettias are ready to ship is when the cyathias open and the stamens or styles protrude from the flower.

Finished Poinsettias

Prestige™ Red – Tips and Basic Culture Product Description:

v  Mid season, red variety with dark green leaves and large showy horizontal bracts

v  8.5-week response time. Flower initiation approximately Sept. 25 for Dec. 1 timing

v  Medium vigor with strong v-shaped architecture

Key Selling Points:

v  Prestige can be grown in a variety of container sizes from 4-12” containers and trees

v  Prestige is ideal for high density growing.

v  Prestige’s natural stem strength and v-shaped architecture eliminate stem breakage.

v  Post production characteristics are outstanding.

Tips for Success:

v  Soft pinch with leaf removal recommended for optimum branching. 

v  Pinching during periods of high light, high heat, and low relative humidity may result in poor branching. 

v  Pot tight spacing after pinching to promote upright branching not necessary. 

v  Responsive to DIF (difference between day and night temps) and PGR’s (plant growth regulators) for height control. A positive DIF is warm day/cool night, which tends to make plants taller. A negative DIF is cooler day/warmer night, which tends to make plants shorter.

v  Sensitive to heat delay.  Maintain night temperatures below 72°F during flower initiation to avoid delay. 

Polar Bear – Tips and Basic Culture

Product Description: v  Bright white bracts and dark green leaves v  8 week response time.  Flower initiation approximately September 15th for November

15th timing.   v  Medium vigor plant habit v  V-shaped architecture

Key Selling Points: v  Bright white bracts position above transitional bracts showing green venation, creating a

nice visual contrast. v  Large cyathia are resistant to premature cyathia drop. v  V-shaped architecture reduces stem breakage. v  Great for a variety of product forms.  v  Outstanding post harvest qualities. v  Resistant to bract edge burn.

Tips for Success: v  Greening or browning of the bracts may occur with cold temperatures. Excessive delay

in development of the bracts or a reduction in bract size may also be a concern. 

Cutting Root Growth after 4 Weeks

Considerations and adjustments to culture For the roots:

v  Avoid growing plants on the floor.

v  Maintain average root zone temperature at 65°F (17°C).

v  Irrigate late morning and finish by 12:00 noon and avoid further cooling of the media with cold water applied early in the day. By finishing midday, the foliage will still dry before nightfall.

v  Plants will be using less water; monitor soil moisture levels closely.

v  Less water uptake equals less nutrient uptake; monitor pH and EC closely to maintain acceptable levels for healthy growth.

v  A preventative fungicide program for root rotting pathogens is important with cool temperature production as conditions will be more favorable for diseases such as Pythium.

v  Check roots once or twice weekly and watch carefully for signs of stress or disease.

Your Job in the Greenhouse v  Keep a lab book. Bring a one-subject lined composition book with you

to every lab. Each lab, you will be taking some data. For example, you will be carefully inspecting the poinsettia plants for any signs of a nutrient deficiencies, pests, overwatering, or underwatering. You will record the height of the tallest, shortest, and an average-height plant in your group.

v  Weekly photos of flower progression and good record-keeping will prove very useful when evaluating the crop. If you can take photos and print some for your lab notebook, that would be fantastic!

v  When interpreting height tracking graphs, growers generally expect earlier height against the standard curve and less height later in the production cycle. Graph your tallest, shortest, and avg.-ht. plant weekly. Note changes in width, coloration, general health, etc.

Greenhouse Worksheet GREENHOUSE WORKSHEET BIO 120   Name: ________________________________ Date: _____________ Arrival Time: _____________   Lab Project(s) you are working on: ______________________________________________________   ____________________________________________________________________________________   ____________________________________________________________________________________   Other work you participated in this week: (Check all that apply.)    ☐ Observing plants for signs/symptoms, growth habit ☐ Weeding ☐ Watering ☐ Fertilizing ☐ Adding or removing shade or black cloth   Is all equipment properly cleaned and put back in its place?   Departure Time: ___________________________________________________________________

☐ Seed starting/testing ☐ Vegetative propagation ☐ Transplanting ☐ Bonsai

Please complete one of these each time you visit the greenhouse. It just takes about a minute.

Let’s go in the greenhouse!