Planting Guide for Poinsettia Production


May 8, 2024
Category: Growing Tips

Are you thinking about adding Poinsettias to your commercial greenhouse? These classic Christmas plants are excellent for adding cash flow during a slow season and providing learning opportunities for permanent greenhouse employees. Poinsettia production is challenging but predictable, and with some knowledge and practice, this plant adds value to any commercial greenhouse holiday program. Poinsettias are easy to sell since customers look for them during the holidays, whether you stock them or not.

Use this thorough guide to plan for success in planting and caring for your Poinsettia liners. 

We’ll cover: 

  • Scheduling and response time
  • Pests and Disease
  • Irrigation
  • Fertilizer
  • Planting and spacing
  • Pinching and PGRs

Scheduling and Response Time

Poinsettias are vegetative long-day plants that initiate color around late September, when nights are longer than days. Region and cultivar influence timing, and varieties are categorized as early, mid, or late-season in response time to long nights. The response time indicates how long from first color initiation it takes for the plant to develop full bract color, anywhere from 7 weeks (very early) to 9 weeks (late).

Since Poinsettias are photoperiodic, be aware of light pollution. This crop requires shorter nights for vegetative growth and longer nights to initiate and complete bract coloration. Any light, natural or artificial, can interfere with coloration. Poinsettia requires full sun after the first four to five weeks after transplanting. 

Order Poinsettia liners to arrive for mid-July to early August planting if you want 6-inch pots ready in late November or early December. Allow this time for vegetative growth, as plants will initiate color in late September, regardless of size. Choose varieties that target your sales window; early response times are well-suited to Black Friday sales, while late response times are great for last-minute shoppers. Growing varieties from each category can provide attractive Poinsettias throughout the season.

Response times for each variety are noted in this catalog for Syngenta and Beekenkamp Plants cultivars or on this page for Lazzeri plants. 

Pest Problems

Scout for thrips, spider mites, shoreflies, whiteflies, and fungus gnats as part of your commercial greenhouse Integrated Pest Management program. 

Fungus Gnats are small, dark flies that lay eggs in damp soil where larvae feed on plant roots, causing damage and death. Watch for adult gnats flying around the plants and check for larvae in the soil. Prevent infestations by allowing the soil to dry between waterings and controlling humidity in the greenhouse. Fungus Gnats thrive in moist conditions. Catch adult gnats with sticky traps to prevent them from laying eggs. Use beneficial nematodes or apply Bacillus thuringiensis.

Whiteflies are small, winged insects that eat plant sap and cause yellowed leaves and stunted growth. Severe infestations can lead to plants dying. Prevent infestations by sanitizing surfaces and tools and removing debris. Introduce beneficial insects or use sticky cards to control populations. Insecticidal soaps and oils are also effective against this pest.

Thrips are tiny insects that eat plant tissue and can transmit viruses. Watch for silvery-white streaks or black spots on foliage and distorted growth. Use natural predators (like predatory mites), insecticidal soap, neem oil, and sticky traps to control infestations and prevent spread. 

Spider Mites are tiny pests that cause stippling, yellowing, and webbing on foliage by feeding on plant sap. They flourish in warm, dry environments. Use correct water and fertilizing practices; over-fertilizing can attract spider mites. Proper humidity levels, predatory mites or ladybugs, and insecticidal soaps or oils may prevent or address a spider mite infestation.

Shore Flies are black flies attracted to algae and organic matter. Watch for adult flies around plants and larvae in the soil. Sanitize surfaces and prevent algae growth in your greenhouse. Remove any extraneous organic matter, use sticky traps to catch adult flies, and use beneficial nematodes to kill larvae. 

Disease Problems

Watch for signs of pythium, botrytis, powdery mildew, Rhizoctonia, and scab. The best treatment for any disease is prevention. Sanitize surfaces, tools, and equipment before use, and use sanitary growing media and containers. Water at the base of each plant, and provide good airflow and adequate spacing in your greenhouse. 

Pythium and Rhizoctonia are fungal diseases that cause stunted growth, yellowed leaves, and plant death by eating away at the plant’s roots. Use well-draining planting media and provide good airflow and spacing in your greenhouse. Allow the soil to dry slightly between waterings and apply fungicides with active ingredients abamectin, spinosad, or imidacloprid to combat these diseases.

Powdery Mildew is a fungal disease that thrives in humid conditions. It appears as a white or gray coating on foliage and flowers. Provide good airflow in your greenhouse. We recommend horizontal airflow fans alongside manual venting to help control humidity levels. Remove and destroy infected plants and apply fungicides as needed or preventatively. Look for the active ingredients myclobutanil, trifloxystrobin, or potassium bicarbonate to combat Powdery Mildew threatening your Poinsettia liners.

Botrytis is a common fungal disease that causes brown spots on stems, leaves, and flowers. To control the spread, remove and destroy affected plants, maintain appropriate humidity levels, and apply fungicides with boscalid, fenhexamid, or iprodione. Water plants in the morning and allow the soil to dry slightly between waterings.

Scab periodically appears in Poinsettias as raised, bleach-white scab-like lesions on stems and leaves and excessive elongation of infected stems. Control and prevent with a spray of Mural at 4-7 oz/100 gallons or Eagle 20EW fungicide at 8 oz/100 gallons. Rotate in products containing mancozeb to prevent scab.

Irrigation Options

When to water

Watering Poinsettias evenly and consistently helps plants develop healthy root systems, strong stems, and consistent bract coloring. Regular irrigation and proper airflow are necessary to manage heat stress. Water stress can cause serious long-term problems with Poinsettia. Allow leaching from the bottom of each pot to prevent fertilizer buildup, and be careful not to get water on the bracts and leaves.

How much water

A gentle overhead watering during the hottest parts of the day will help with managing heat stress. Late-day irrigation schedules work the best in the vegetative part of Poinsettia production when outdoor temperatures are high.

After color initiation, continue to water consistently, provide adequate spacing, and don’t overwater plants. Plants grown colder use less water.

Feeding Poinsettia

Pay attention to the relative vigor of the Poinsettia cultivars you choose to grow as you determine which fertilizer and PGR to use for growing the strongest, healthiest plants.

At transplant, feed each Poinsettia liner with a 20-10-20 fertilizer. Ongoing, use a constant liquid feed at 225-250 ppm N for dark-leaf varieties or 250-275 ppm N for medium-green-leaf varieties. 

Want to dial in the Fertilizer?

Encourage more toned growth and smaller foliage early on by using a 17-5-17 or 15-5-15 Cal-Mag fertilizer. 

Once your plants are more established, use a 20-10-20 fertilizer plus Molybdenum or a 20-5-19 Poinsettia formulation and alternate with a 14-0-14 or similar from mid-October to November 1. This feeding program will encourage soft, lush growth and larger plant size. 

If you add Molybdenum to basic 20-10-20, create a stock tank by mixing .25 TSP Mo/1 gallon water and 15 oz fertilizer/1 gallon water and inject this concentrate at a 1:100 ratio.. 

Target Fertility

Poinsettias enjoy a constant feed rate of 225-250 PPM. After November 10th, gradually reduce the feed by about 75% and give two strong clear-water leaches before shipping.

General Growing Pointers

Planting

Some varieties are versatile, excelling in small or large containers, while others are more suited to one or the other. Note the recommendations for the specific cultivars in your commercial greenhouse. 

Plant one Poinsettia liner per 4 or 6-inch container or three to five per 8 or 10-inch container. Use a porous peat-based soil with good drainage and bury the ellepot level with the soil, evenly spaced or centered in the container. 

Use a drench of a fungicide containing thiophanate-methyl to prevent fungal root diseases. Provide light shade for new transplants for four to five weeks, especially in the South. 

Pinching

Pinching is required for the development of lateral branches. Pinch Poinsettia liners once, two to three weeks after transplanting, after the plugs have developed roots in the final container. Remove premature stocks from the bottom nodes. 

Pinch at seven nodes for six fully developed branches in 6-inch pots. For 4-inch pots, pinch on four or five leaves. For large containers, pinch on seven to nine nodes, adjusting for the final number of bracts needed to fill the pot. Provide light shade for two weeks after pinching and then provide full sun. 

PGRs

It’s always best to conduct small-scale trials before large-scale use of less traditional Poinsettia PGR applications.

PGR needs vary among Poinsettia varieties. Rely first on consistent day and night temperatures to control height. Pay attention to the relative vigor of the varieties you grow and monitor rapid-growing phases. 

When daytime temperatures exceed nighttime temperatures by more than five degrees in Northern climates, use Cycocel growth regulator treatment at 750-1,000 ppm one to four times after pinching. With daytime temperatures above 80 degrees and nighttime temperatures above 70 degrees, the plants will need more PGR; spray Cycocel (1,000 ppm) plus B-Nine (1,500 ppm) tank mix one to three times during the one to four weeks after pinching. Alternatively, use a Florel spray at 500 ppm three to five days before pinching, three to five days after pinching, and again three to five days later for vigorous varieties. Don’t use Cycocel, B-Nine, or Florel after color initiation. 

You may use micro drenches of paclobutrazol after color initiation and before 50% color at 0.05-0.1 ppm. The higher rate is for vigorous varieties for moderate growth control. The lower rate is for medium vigor varieties for slight slowing of growth. Total accumulated Bonzi drench shouldn’t exceed 0.25 ppm until bracts are at least 50% colored to avoid delaying color and reducing bract size. Consistently drench each container with fl. oz/1 inch pot diameter. Apply a final Bonzi drench 3-4 weeks before finishing at 0.5-1.0 ppm in the North and 1-2 ppm in the South. 

If the crop is below the target height, early sprays (up to mid-October, at the beginning of color development) of gibberelic acid at 2-3 ppm can encourage 2-4 inches of growth within 2 weeks after application. Don’t spray gibberelic acid late to avoid undesirable bract shape and internode stretching. 

Spacing

Provide proper spacing for your pots to avoid leggy, weak plants and to allow for adequate airflow. Grow Poinsettia liners pot tight until the foliage begins to touch, and then space containers to help plants grow in an upright, attractive v-shape. Spacing containers too early causes horizontal growth and more breakable stems. Final spacing depends on cultivar and target size, and some varieties are well-suited for high-density bench production.

  • 6 Inch Pots: 15″ centers
  • 8 Inch Pots: 25″ centers

Offer Poinsettias to customers as part of your winter holiday program. Poinsettia is the shining star of every festive display in the greenhouse and home during the Christmas season. Bold, star-shaped leaves and classic reds and whites or novelty pinks, creams, and variegated bracts usher in the Christmas spirit, excelling indoors. A seasonal favorite among customers, Poinsettia flourishes in bright indirect light and temperatures between 65-70 degrees. Grow Poinsettia alongside African Violets, Christmas Cactus, and small pine or juniper trees. Grow red varieties with novelty and white varieties for a striking display of holiday colors.