June 2008

Crop Culture Report: Petunia Picobella Series By Jeannine Bogard

Picobella is the next generation of milleflora petunias. Dwarf habits with petite 11?2- to 2-inch flowers make these miniature petunias so special that a new class of petunias was created to classify them. The Fantasy series launched the class of milleflora petunias, and Picobella takes it into the 21st century with major improvements to plant performance and cultural requirements.

Beyond its beauty, this mini petunia can be grown and sold the entire bedding-plant selling season, is not a space hog, and can be shipped easily and efficiently. Picobella dwarf petunias have been bred specifically for increased plant vigor that results in a slightly larger and fuller plant that quickly fills a container or garden bed. This improved vigor also makes Picobella more tolerant of cold and/or wet conditions.

Flowering Mechanism

The key to growing a successful Picobella crop is understanding the flowering mechanism of this unique miniature petunia. Because Picobella is receptive to flower initiation when three to four leaves are present, it will be necessary to keep the young plants in a vegetative state to allow the plant to bulk up prior to bud set. If the plants are allowed to initiate blooms too early, the crop may not size up properly for larger containers. Flowering is affected primarily by irradiance and temperature. Day length has a minor effect on flowering.

Under winter/early spring growing conditions, typically January to March, to bulk the plant up sufficiently and support abundant flowering:

• Do not expose the plug trays to supplemental lighting. Irradiance should not exceed 6 moles or 3,500 foot-candles.
• Provide a day length less than 10 hours.

Once the plant has bulked up to a desired size, the optimum conditions to induce flowering include light levels greater than 6 moles and an average daily temperature of 65-66¡ F, a minimum day length of 101?2 hours. Bottom line: It is important to obtain the necessary shoot growth prior to bud set to produce a quality crop.

Plug growers will benefit from the uniform and strong germination of Picobella, while finish growers will find the petite, controlled habit very manageable on the bench. A tight flowering window encourages bench run sales.

As with most petunias, during flower initiation, night temperatures below 55¡ F will delay flowering and reduce the number of buds initiated. After bud set, night temperatures can be lowered to 50¡ F to encourage basal branching and compactness.

Light conditions will determine the feed strategy to produce a compact, high-quality plant. Under high-light conditions, apply an ammonium-based feed (17-5-17). To prevent stretching under low-light and cool conditions, a calcium-based feed (14-4-14) is preferred. Keep the soil pH at 5.5-5.8 with an EC around 1.2.

Genetically dwarf, Picobella varieties offer the advantage of requiring little to no growth regulators. This should be good news for those growers working toward sustainability protocols. If desired, under very high temperatures, a low rate of B-Nine (daminozide) may help tone plants.

Crop time is four to five weeks in a 288-plug tray. Depending upon the final container, crops should finish in four to six weeks from transplant.

To maximize impulse sales and obtain quick turns at pay by scan retailers, ship Picobella with 75 to 90 percent color. The unique characteristics of this petite petunia will not be obvious without a lot of color showing.

Retail Ready

Picobella may be small in stature, but it elicits a profusion of color. It is suitable for 4-inch bedding or 10-inch hanging basket promotion, as well as in mixed containers, wall bags, and traditional packs and flats.

Great selling points include a plant that blooms quickly; a mounding, controlled habit that will not take over tabletop dish gardens or crowd out other container plants; and loads of petite flowers on a proportionately appropriate plant.

Landscape Beauty

Garden performance has been a significant focus of Goldsmith's breeding efforts of the Picobella series. Emphasis has been placed on developing milleflora hybrids that have strong vigor to perform over a wider range of climates, yet retain their petite dwarf habits and multitude of blooms.

Perfect for small-space or vertical gardening, landscapers will appreciate that the non-splitting plants stay neat and tidy all season long. Picobella is also tolerant to cold and wet (or heat and high-light) conditions.

In the garden, the low-mounded, controlled habit of Picobella can be used for intricate design work, large beds or border edges. The continuous flowering produces a dense canopy of blooms. Plant on 6- to 8-inch centers for maximum visual impact.

Picobella is currently available in Blue, Carmine, Light Lavender, Rose, White and a Mixture that includes Red.