Bedding Plants for Interiors
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Charles A. Conover, Ph.D. and Loretta N. Satterthwaite(1)
University of Florida, IFAS,
Central Florida Research and Education Center,
2807 Binion Road, Apopka, FL 32703-8504.
CFREC-Apopka Research Report RH-96-3
Foliage plants usually dominate in interior plantscapes because they have evolved under light levels similar to interior light levels, or they can adjust to interior light levels, temperatures and humidity without marked loss of quality. Foliage plant longevity in interior environments has been enhanced by acclimatizing plants to indoor conditions through the use of recommended production, shipping and storage practices developed through research. Interiorscapers already use flowering plants to provide accents to foliage plants; however, only a few flowering plants are available that will last indoors for three weeks or more. Using short-lived blooming plants in interiorscapes creates a labor-intensive situation because either the unattractive blooms must be removed from the plants or entire plants must be replaced to maintain an appealing setting; however, they provide much needed color accents. If blooming/bedding plants could be found that flower indoors for periods of time equal to or greater than the commonly used flowering plants, they could also be used as color accents at lower cost than most of the commonly used potted flowering plants.
With this concept in mind, a proposal was submitted to the Bedding Plant Foundation, Inc. entitled "Selection and Production of Bedding Plants for Interiorscapes". The purpose of the proposed research was to determine whether or not certain bedding plants have potential to serve as short-term color accents in interior landscapes.
After approximately three years, data on several groups of bedding plants indicate that there is potential for their use in interiors. Although the research is not finished, the data is positive and warrants reporting.
The research was organized to determine the nutritional levels needed to produce high quality bedding plants with potential for interior longevity. During production in a glass greenhouse with maximum light intensities ranging from 4500 to 6500 ft-candles, bedding plants in 4-inch pots were fertilized with 14-14-14 Osmocote at either 0.04, 0.05, 0.07 or 0.09 oz. When the crop was ready-for-market, plants were moved into interior environments where light intensities were either 75, 150, 225 or 300 ft candles (12 hours/day) from cool white fluorescent lamps and plant responses (quality, growth, flower number, etc.) were recorded at 3-week intervals. Cultivars that maintained satisfactory quality for 3 or more weeks under 150 ft-c were considered promising. In addition, shipping trials (duration and/or temperature) were conducted on many genera.
Results
The following tables give a broad overview of the lasting capabilities of several plants tested. No plants were kept under interior conditions more than 9 weeks; a 9+ indicates that the average grade for the plants in that particular treatment were still satisfactory at the time of experiment termination.
More than three weeks (3+) or less than six weeks (<6) can be interpreted to mean approximately the same thing, but generally a 3+ would indicate that the plants were satisfactory at 3 weeks, but declined to an unsatisfactory quality soon thereafter, and closer to 3 weeks than to 6 weeks. Conversely, less than six weeks (<6) would indicate that the plants remained satisfactory closer to six weeks than three weeks, but were of unsatisfactory quality by the 6-week grading period. Less than 3 weeks (< 3) means that the plants under the indicated light level were of unsatisfactory quality by three weeks after being moved into interior rooms.
Table 1. Begonia cultivar that maintained a satisfactory quality for 3 or more weeks.
Plant testedDuration of acceptable quality (weeks) Light intensity (ft candles)
Begonia x semperflorens-cultorum 75 150 225 300 'Bingo Pink' 'Olympia Red'
'Prelude Pink'
'Prelude Scarlet' (2 trials)
'Prelude White'
'Vodka' (2 trials)
<3 9+
3
<3
3
<3
9+ 9+
6+
9+
6+
9+
9+ 9+
6+
9+
6+
9+
9+ 9+
6+
9+
6+
9+
Table 2. Celosia cultivars that maintained satisfactory quality for 3 or more weeks.
Plant testedDuration of acceptable quality (weeks) Light intensity (ft-candles)
Celosia plumosa 75 150 225 300 Castle 'Pink' Castle 'Scarlet'
Castle 'Yellow'
Geisha Mix
Kimono Mix
'New Look'
<6 6
3+
3+
3+
6+
9+ 9+
3+
6+
3+
9+
9+ 9+
3+
6+
6
9+
9+ 9+
3+
6+
6+
9+
Table 3. Coleus cultivars that maintained satisfactory quality for 3 or more weeks. Plant tested Duration of acceptable quality (weeks) Light intensity (ft-candles)
Coleus 75 150 225 300 Wizard 'Golden' Wizard 'Red'
Wizard 'Rose'
Wizard 'Sunset'
Wizard 'Velvet'
3+ <3
<6
<3
6+
3+ 3
9+
3+
9+
3+ 3+
9+
3+
9+
3+ 3+
9+
3+
9+
Table 4. Celosia, Dianthus and Torenia cultivars that maintained satisfactory quality for 3 or more weeks.
Plant testedDuration of acceptable quality (weeks) Light intensity (ft-candles)
75 150 225 300 Celosia cristata 'Jewel Box' Mix Dianthus chinensis 'Telstar Picotee'
Torenia fourferi 'Clown Rose'
<6 <3
3+
<9 3
3+
9+ 3+
3+
9+ 3+
3+
In general, longevity of these plants can be increased by using low fertilizer rates during production and high light intensities in interior settings. Low to moderate levels of fertilizer (0.04 oz to 0.05 oz per 4-inch pot) produce the best plants for indoor use. Light intensities of at least 150 ft-c increases longevity of most plants although there are some plants which can last for 3 or more weeks under 75 ft-candles. In most cases, shipping plants under temperatures ranging from 55 to 75F for 3 days has made little or no difference in interior longevity.
Other plants tested that may show some potential for indoor use, but data thus far are inclusive, are: Ageratum houstonianum Hawaii 'Blue'; Dahlia 'Figaro Improved'; Dianthus chinensis Telstar 'Crimson' and 'Purple Picotee'; Hypoestes 'Pink Splash Select' and 'Rose Splash Select'; Impatiens wallerana Dazzler 'Scarlet Plush', Showstopper 'Red', and Super Elfin 'Red' and 'Scarlet'; Salvia splendens Empire 'Purple' and 'Red'; Tagetes patula (French marigold) Bonanza 'Deep Orange' and 'Yellow', and Safari 'Gold' and 'Queen' and Torenia fourieri Clown 'Blue' and 'Purple'.
Several plants were also tested that were deemed to not have potential for indoor use because they did not exhibit a satisfactory quality, or were only marginally acceptable, after three weeks in interiors under all light intensities tested. These plants included: Antirhinnum majus (snapdragon) Tahiti 'Appleblossom' and 'Bicolor'; Helianthus annuus (sunflower) 'Big Smile', Tagetes patula Janie 'Golden Orange'; and Zinnia elegans Peter Pan 'Flame', 'Gold', 'Orange', 'Pink', 'Plum', and 'Scarlet'.
Conclusions
The cultivars listed in Table 1 through 4 are not expected to replace foliage plants in interiors. What they can do is provide color accents that are different from the ones commonly used. In addition, bedding plants remind people of Spring and Summer and at times, especially in the north, that could be both economically and psychologically beneficial. Use of color accents is most common in mall and other large commercial plantings and that is where bedding plants in small mass plantings can serve best. In these locations the necessary light levels will be present and since bedding plants can tolerate cool temperatures, mall temperatures will be conducive to increased longevity.
These findings show that there are bedding plants that have potential for use in interiors. This knowledge should allow alternatives for color in interiors and open new markets for bedding plant producers.
Additional Reading Material
Conover, C. A., L. N. Satterthwaite and K. G. Steinkamp. 1993. Production fertilizer and postharvest light intensity effects on begonias. Proc. Fla. State Hort. Soc. 106:299-302.
1. Professor of Environmental Horticulture and Center Director, and Technical Assistant, respectivly, Central Florida Research and Education Center-Apopka, 2807 Binion Road, Apopka, FL 32703.