petunia Fun House Potpourri

Culture Report: Petunia ‘Fun House Potpourri’ By Alicain Carlson and Cecilia Guo

This uniquely colored new petunia is a fun addition to baskets and patio containers.

Potpourri — the first introduction in the new vegetative Fun House petunia collection from Syngenta Flowers — makes its debut this year with its unique morphing colors and pattern depending on how it’s grown. It has a mounded, trailing habit for a fun addition to hanging basket and patio container programs and makes a great addition to combos. Read on to learn how to propagate, finish and manipulate the color of ‘Fun House Potpourri’.

PROPAGATION

Stick

‘Fun House Potpourri’ is propagated similarly to other petunias on the market. We recommend sticking cuttings into a 105-cell tray or larger. Bottom heat temperatures should be between 70 and 74° F for the first three weeks. After roots are well developed, temperatures can be lowered to hold and tone the cuttings. You should see root emergence in six to eight days. Rooting hormone is not recommended.

Irrigation

Mist schedules vary depending on light and temperature conditions. Apply just enough moisture to rehydrate the cuttings and keep them from wilting. Cuttings should be rehydrated within 24 hours after sticking. Cuttings that continue to wilt heavily after 24 hours will callus unevenly and will be delayed in rooting. CapSil (spray adjuvant) can be sprayed on the cuttings at a rate of 2 to 4 oz/100 gal within one to two days after sticking to aid rehydration. Misting should be significantly reduced after two to three days and after cuttings become fully hydrated. Petunias are particularly sensitive to over-misting, which can lead to chlorotic and deformed foliage and growing tips.

Temperature and Light

Day and night temperatures of 72 to 74° F are recommended. Petunias are facultative long day plants so day length extension lighting up to 14 hours is beneficial though not necessary. Providing long days in the plug stage can reduce overall time to flower. A light intensity of 1,000 to 1,200 foot-candles (200 to 250 micromoles) for the first two weeks after sticking or until root development occurs is recommended. Light levels can be increased up to 3,000 foot-candles (600 micromoles) as rooting increases and the cutting matures. Light, in terms of daily light integral (DLI), is ideal at 4 to 6 mols/day for the first two weeks from stick until root development occurs, and then it can be increased to greater than 12 mols/day.

Media and Nutrition

Begin fertilization at 100-ppm nitrogen when roots become visible. Rates can be increased up to 200-ppm nitrogen after roots become well developed. Use primarily lower ammonium-nitrogen based Cal-Mag Plus (calcium nitrate + magnesium nitrate) fertilizers in propagation to prevent unwanted stretch. Supplemental feeding with additional iron (i.e., iron chelate) will help prevent iron deficiency and leaf tip chlorosis. Maintain media pH between 5.6 and 6.0 and media EC between 0.9 and 1.3 via Saturated Media Extract (SME).

Plant Growth Regulators

‘Fun House Potpourri’ has good vigor and generally will need chemical growth regulation in propagation. To control growth after rooting, sprays of B-Nine WSG (2,500 to 3,500 ppm) are effective. A tank-mix spray of Florel (350 ppm) + B-Nine WSG (2,500 ppm) can also be used to control growth and improve branching. Do not spray Florel on stressed or weak cuttings. For all sprays listed above, the mist should be off for a minimum of one hour for the PGR to absorb into the leaf tissue. Pinching is not recommended during

propagation. Your liners should be ready to ship and transplant into the finish container in three to three-and-a-half weeks from a 105-cell tray.

FINISHING

Transplant and Pinch

Transplant plugs directly into the finished container. Place the rooting media slightly below the level of media in the container. For plants per pot recommendations see Figure 1. One pinch is recommended seven to 10 days after transplant for large containers and may not be necessary for small containers, as Potpourri naturally branches well. A second pinch can be given to plants grown in large baskets and containers and can be done shortly before a final Bonzi drench.

Temperatures and Light

‘Fun House Potpourri’ petunias should be grown at an average daily temperature of 66 to 68° F with 70 to 72° F day temperatures and 62 to 64° F night temperatures. Early morning DIF treatments will help keep plants more compact. Day extension lighting is beneficial to 14 hours, though Potpourri will flower readily at 11.5-hour long natural day lengths. Providing long day lighting during short days will shorten time to flower and increase flower numbers as petunias are facultative long day plants. Aim for light intensities between 4,000 to 6,000 foot-candles (800 to 1,200 micromoles) and a DLI of 16 to 18 mols/day. Temperatures can be lowered three weeks after planting and especially toward the end of production to tone or hold the plant. High DLIs and cool finishing temperatures produce high-quality petunias.

Media and Nutrition

Media pH of 5.5 to 5.9 and EC of 3.5 to 4.2 via PourThru are optimal. Feed with 200- to 250-ppm nitrogen. Media should be allowed to dry between irrigations, alternating between moisture level 2 (medium) and 4 (wet). Keep media pH in the mid 5 range to avoid iron deficiency and tip chlorosis.

Pests and Diseases

Use proper sanitation when pinching or shearing petunias. Petunias and other solanaceous crops are highly susceptible to the Tobacco Mosaic Virus (TMV), which can be easily transmitted by mechanical means. Common pests to prevent and scout for are thrips, aphids, budworms, leafminers and whiteflies, and common diseases are Botrytis and powdery mildew.

Color Pattern Manipulation

The flower color and star pattern can be manipulated with PGRs, light intensity and temperature. When managing growth during finish, sprays of B-Nine WSG will turn flowers completely yellow (Figure 2). The number of B-Nine WSG applications and higher concentrations used will affect how long flowers remain clear yellow and will delay the expression of the bicolor flower pattern. Under average growing conditions, the color change can happen approximately nine weeks after the last B-Nine WSG application.

DLIs lower than 10 mols/day will cause flowers that are more muted in color. Color will become more bright and vivid after exposure to higher DLIs (Figure 2). The flower pattern of ‘Fun House Potpourri’ is not influenced by photoperiod.

To get the true bicolor pattern use Bonzi drenches to control growth in finished production and grow consistently at low night temperatures below 62° F. Night temperatures above 66° F will result in nearly all pink flowers. The effects of other PGR active ingredients are being investigated.

General PGR Recommendations

It is best to be proactive in applying PGRs on petunias. Anticipate changes in weather or other conditions that can cause plant stretch and apply PGRs before plant stretch begins. ‘Fun House Potpourri’ has good vigor and will generally need chemical growth regulation. Sprays of B-Nine WSG (1,500 to 5,000 ppm) or Sumagic (20 to 30 ppm) can be used to control growth. A tank-mix spray of Florel (350 to 500 ppm) + B-Nine WSG (1,500 to 2,500 ppm) can also be used to control growth and improve branching early in production.

Keep in mind the color changing effects of B-Nine WSG outlined in the previous section if choosing this option. A Bonzi drench (2 to 4 ppm) can be applied three to four weeks before finishing and results in toned, high-quality plants. Bonzi drenches (2 to 4 ppm) can also be utilized through production to control growth. Providing cool temperatures, high light, and “growing on the dry side” will help keep petunias more compact without reliance on chemistries. Early morning DIF treatments also help.

POSTHARVEST

Petunias, in general, are notorious for their flower meltdown at retail due to the stressors of shipping. For best postharvest quality and longevity, apply Chrysal Alesco as flowers first begin to open to help protect plants from ethylene build up during shipping so they have more color at retail. If two or more weeks will pass between first color and shipping, apply Alesco again one to two days before shipping for maximum protection. Protecting the flowers during shipping also helps to prevent secondary Botrytis infection that is known to occur on the prematurely senesced flowers of untreated plants.

Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties and/or may have state-specific use requirements. Please check with your local Extension service to ensure registration status and proper use. Some or all of the varieties may be protected under one or more of the following: Plant Variety Protection, United States Plant Patents and/or Utility Patents and may not be propagated or reproduced without authorization.



Alicain Carlson and Cecilia Guo

Alicain Carlson, Ph.D., is the technical trial manager and Cecilia Guo, Ph.D., is the technical scientist for Syngenta Flowers North America.



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