Topic #2172 Foliage Plants

Focus on Poinsettias

By: Alisa Kowalski

Major Foliage Crops

1. Poinsettias

2. Chrysanthemums

3. Easter Lilies

4. Florist Azaleas

Minor Foliage Crops

1. African Violets2. Cineraria3. Cyclamen4. Holiday Cacti5. Kalanchoe6. Gerbera Daisy7. Gloxinia

Poinsettias I

• Euphorbia pulcherrima

• Native to Mexico

• Named after Joel Poinsett, former US Ambassador to Mexico

Poinsettias II

• #1 Potted Flowering Crop in US

• Wholesale Value: >$123 million/year

• Grown for showy bracts which are modified leaves

Poinsettias III

• Cyanthia- small, yellow, bud shaped structures in the center of the bracts (flowers)

• Short day or long night plant

• Require at least 12 hours of darkness

Poinsettia Cultivars

• Annette Hegg Series

• Echespoint Series

• Gutbier Series

• Mikkelsens Series

Poinsettia Cultivation

• Vegetatively propagated by tip cuttings

• Available rooted or unrooted

Poinsettia Stock Plants I

• Cuttings received in March-May• Night interruption lighting • Prevent flower initiation• After rooting

–6”-10” pot–50ºF- Night Temperature–80ºF- Day Temperature

Poinsettia Stock Plants II

• 2 Pinches before cutting• First pinch

– leave 8-11 nodes–7-10 days after planting

• Following pinches– leave 2 nodes on new growth

Poinsettia Cuttings I

• Cuttings taken~4 weeks after last pinch

• Key factors to success–Cleanliness–Mist System–Optimum Temperatures

• 3-4 inches using hands or knife

Poinsettia Cuttings II

• Place in

–6 inch pot or –artificial media

•examples: rock, wool, or foam

–Mist system immediately

Poinsettia Cuttings III

• Bottom heat–speeds rooting–Media temperature 70°F -75°F

• Misting leaches nutrients–7-10 days after planting–use a 150ppm-200ppm fertilizer solution

Poinsettia Cuttings IV

• Misting–decrease interval after callusing

• Remove from mist–when good roots have formed–put in final spacing at this time

Growth Requirements ~ Media

• Good Example of Media: Equal parts loam soil, peat moss and perlite–High porosity–High water holding capacity–Sterile–pH= 6.0 to 6.2

Growth Requirements ~ Watering

• Require large amounts of water• Should not be allowed to wilt • Overwatering can cause root rot• Examples of watering systems

- Spaghetti tubes - Capillary mats

- Subsurface Irrigation - With hose

Growth Requirements ~ Fertilizing I

• Large amounts of fertilizer requirements Especially Nitrogen

• Constant liquid feed of 250-300 should fulfill the requirement for established plants

• Amount required may be affected by:– light & temperature levels

• Weekly pH & EC test is suggested to measure the effect of these

Growth Requirements ~ Fertilizing II

• Poinsettias are sensitive to ammonia toxicity– Caused by an excess of 305 Ammonium

nitrogen

• Calcium deficiency can cause bract necrosis & weak stems– To combat this a trace element mix

should be added once during production

Growth Requirements~ Temperature I

• Average Daily Temperature affects development

• To enhance bract color – During finishing reduce night

temperatures to 55-60F

Growth Requirements~ Temperature II

• Average Daily Temperature affects development

• Optimal temperatures– Night- 65F

•If below- delay flower initiation

– Day- 70-75F•If above- reduces flower quality

Growth Requirements ~ Light

• To keep plants vegetative– Night interruption of 10 fc from 10 PM to

2 AM • High light levels during the day

influence growth• Plants will bloom when days are less

than 12 hours– A black cloth may be used to shield plants

from outside sources of excess light

Growth Requirements ~ Pinching

• No Pinching = One Large Flower

• Most plants are pinched 2-3 weeks after transplanting & once the plant has established a sufficient root system

• It is common for plants to be pinched to 3-5 nodes

Growth Requirements ~ Pinching

• Top 1/2 to 1 inch of plant is removed

• More nodes left on stem = more flowers– If more flowers are allowed to form,

they will be smaller that if fewer flowers were to flower

Growth Requirements ~ Height Control I

• Controlled by adequate spacing

• If plants are shaded they will stretch & elongate

• DIF can also be used– A DIF of 0 to a negative number can

slow growth

Growth Requirements ~ Height Control II

• Chemicals can also be used• Common Chemicals include:

– Cycocel– B-nine– A-rest– Bonzi– Sumajic

• Be Sure to Read the Label and Instructions!

Problems for Poinsettia Growers

• Insects

– Whitefly– Fungus Gnat

• Use IPM to control these insects

Diseases of Poinsettias

• Bostrytis- gray mold– Prevent by providing low humidity

and good air circulation

• Rhizoctonia- stem and root rot– Control with fungicide

• Pythium- water mold and root rot– Control with fungicide drench

Physiological Problems I• Bract Burn- Condition in which tips of

bract turn brown– Controlled by not applying high ammonium

fertilizers and maintaining calcium levels

• Center Drop- Condition in which flower buds abscise due to carbohydrate depletion– Controlled by maintaining proper

temperature and maximizing light penetration

Physiological Problems II

• Stem Splitting-Condition in which the terminal bud is aborted and three shoots develop into a whorl

–Controlled by providing appropriate night temperatures

Post Harvest & Handling

• Cool finishing temperatures and lessen fertilizer applications

• Plants should be sleeved to ship and unsleeved as soon as possible to minimize droopy leaves

• Plants should be stored at 50-60F and in bright lights