This plant was separated from petunia (taxonomically) in 1825. Many taxonomists believed that the two genera should be one in the same, but in 1985 it was determined that Calibrachoa had 18 chromosomes, while petunia had 14.
In 1988 wild samples were collected from South America and, after breeding, the first 'Million Bells' was released in 1992. Currently Calibrachoa is available in a wide range of colors, from purple-blue, soft lavender-pink, hot pink, cherry pink, white, apricot and yellow. Many breeders have given the selections series names, and these include 'Aloha', 'Million Bells', 'Liricashower', 'Callie', 'Calipetite', 'Celebration', 'Cabaret', 'Lindura', 'MiniFamous', 'Cruze', 'Conga', 'Colorburst', and 'Superbells'. Double forms are also available.
Calibrachoa does best in full sun and is fast-growing with hundreds of small, petunia-like flowers from spring through late fall. The plants are self-cleaning and have a low-growing, compact growth habit. Calibrachoa is a perfect candidate for hanging baskets, window boxes, or planted as a ground cover.
Most Calibrachoa selections are vegetatively propagated from cuttings, but in 2014 Pan American Seed introduced the first series of Calibrachoa from seed, the 'Kabloom' series. Kabloom series plants are 8-12" tall, and 10-14" wide. Plant time for rooted cuttings is from February to March for a spring finish, placing three liners per 8- or 10-inch pot, or one liner per 4- or 6-inch pot. Liners will finish in 9 to11 weeks in 8- or 10-inch pots and 6 to 7 weeks in 4- or 6-inch pots. Calibrachoa requires very high light and grows best in full sun during production.
The Kabloom series crop time is 5-8 weeks for plugs or liners, and 7-11 weeks from transplant to finish. Provide finishing temperatures of 65-70°F for Calibrachoa. Most growers give one soft pinch at liner planting, but a second pinch will provide a full well branched plant. Florel can be effective in creating better branching for upright pots and hanging baskets with longer crop time. Other recommended PGR's include Bonzi, Sumagic, and A-Rest.
The Calipetite series is bred for compact habit, and generally will not need PGR's. Growing media should be kept moist to avoid wilting. Maintain a pH of 5.5-6.0. Watch for iron deficiencies (new growth turning yellow) associated with high pH. Constant feed with a complete fertilizer at 200-300 PPM nitrogen. Extra iron may be required to promote good leaf color. Use of slow-release fertilizer in supplementing a constant liquid feed program may benefit your customer. Provide periodic clear water applications if excess soluble salts accumulate. Calibrachoa is susceptible to aphids and Pythium root rot. Drench a fungicide labeled for pythium, especially on upright varieties just after transplanting.
One hundred and seven selections of Calibrachoa were tested in the Penn State Flower Trials in 2014, along with 5 double forms. All selections performed fairly well, and some were outstanding in their growth and bloom quantity. The top performers included: 'Cabaret White Improved', 'Mini-Famous I-generation Orange', 'NOA Violet', 'Lindura Light Blue', 'Lindura Neon', 'Aloha Tiki Neon', 'Superbells Lemon Slice', and 'Calipetite White'. The top performing double form was 'MiniFamous Double Purple'.