Simulated Home Gardener Care of Containerized Begonia 'Vodka': Effects of Shade and Fertilizer on Beauty and Longevity

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C.A. Conover, Ph.D., Rex Flohr and Russell Caldwell*

University of Florida/IFAS
Central Florida Research and Education Center
CFREC-Apopka Research Report RH-94-8

Sales of bedding plants grown in moveable containers or planters are becoming increasingly popular. These bedding plants add instant color and beauty to the landscape and increase the gardening options available for people who don't have a lot of space outdoors for ground beds. However, plants in these containers can face a harsher micro-climate (temperature and moisture extremes) than plants massed together in ground beds. For long lasting color in containers, plants that can withstand climate extremes of temperature and light should be chosen.

In central Florida, many bedding plant species suitable for cooler, less humid climates deteriorate quickly when planted in Florida's heat and humidity. Fibrous-rooted begonias (Begonia semperflorens) are among the limited number of bedding plant species that can be successfully maintained in beds under full sun conditions throughout the year. In central Florida, people usually use begonias in full sun locations exclusively.

In the Research Gardener program at CFREC-Apopka, one volunteer, Rex Flohr, is working with bedding plants grown in 8-inch tubs in an effort to help the home gardener provide care that will maximize the beauty and longevity of containerized bedding plants. Rex conducted the following tests to compare growth and quality of Begonia 'Vodka', in 8-in containers, in full sun or shade conditions, when fertilized at three different rates.

Begonia 'Vodka' plugs were transplanted into 4-in pots using Bacto Custom Blend Mix (Michigan Peat Co., P.O. Box 980129, Houston TX, 77098) on February 2, 1993. Plants were grown for seven weeks in a glass greenhouse where maximum light intensity was 3000 to 5000 ft-c and air temperatures ranged from 65 to 90°F. On March 24, 1993, Begonia 'Vodka' were transplanted into 8-in containers using the same potting medium mentioned earlier. Size and quality of plants were typical of products in 8-in containers offered for sale by mass merchants. Begonia 'Vodka' were now ready for simulated home gardener conditions.

This was a 3 (fertilizer rate) x 3 (light intensity) factorial test with 8 replications per treatment. Plants were placed in full sun on black ground pack or in a shadehouse under 50 or 60% shade provided by black polypropylene shadecloth. Begonia 'Vodka' were fertilized with 4, 6 or 8 g/8-in pot 14-14-14 (N-P-K) Osmocote (Grace/Sierra Horticultural Products Co., 1001 Yosemite Dr., Milpitas, CA 95035) on March 25, 1993. Plants were watered overhead as needed, every day for plants in full sun, and two to three times per week for plants under shade.

Initial height and width (cm) were measured on March 30 and final height and width (cm) were obtained on May 25, 1993. Plant size was determined by the formula (height + width) ÷ 2. Growth was defined as plant size on March 30 subtracted from plant size on May 25, 1993. Number of flower stalks (with more than one bloom) per plant was counted on April 27, May 11 and May 25, 1993. Plants were graded on May 25, 1993, based on a scale of 1 = dead, 2 = poor quality, very unattractive, 3 = fair quality, acceptable, 4 = good quality, attractive and 5 = excellent quality, very attractive.

Results

Plant growth, flowering and quality were affected by both shade and fertilizer levels (Table 1). Best quality 'Vodka' were plants under 50% shade. These plants had more new growth and flowers compared to plants under other light levels. While Begonia 'Vodka' under 60% shade were of good quality when the experiment was terminated, plants that had been placed outdoors under full sun were in barely acceptable condition.

Plant growth, flowering and quality also increased as fertilizer rate increased from 4 to 8 g/8-in pot. In this test, Begonia 'Vodka' in 8-in pots outdoors under full sun from March 25 until May 25 slowly deteriorated as summer approached, bringing increasingly hot and humid weather; whereas, those under shade were of good to excellent quality.

Conclusions

Quality, growth and flowering were better when plants in 8-in containers were grown and maintained under 50% shade. Plants under 60% shade grew slower and produced less flowers than plants under 50% shade. Growth on full sun plants was much more compact compared to foliage on other plants tested, adversely affecting plant quality. For greatest consumer satisfaction, we recommend planters of Begonia 'Vodka' be placed in a moderately shady location in the landscape during the spring and summer months in central Florida.

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*Professor of Environmental Horticulture and Center Director (retired 7/96), Research Gardener, and Biological Scientist, respectively, Central Florida Research and Education Center, 2807 Binion Road, Apopka, FL 32712-8504.

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References

Tietz, Heidi. 1991. Begonia. Section in textbook: Ball Redbook, l5th edition, V. Ball editor, G. J. Ball Publishing 662 Town Road, West Chicago IL. pp 395-396.

Table 1. Effects of light and fertilizer levels on growth, flowering and plant quality of Begonia 'Vodka' .

^zPlants were maintained outdoors on black ground pack under full sun, in a shadehouse under 50% shade or in a shadehouse under 60% shade, from March 25 until May 25, 1993.
^yPlant growth (cm) was measured as final (height + width). 2, (measured on May 25, 1993), subtracted from initial (height + width). 2, (measured on March 30, 1993).
^xNumber of flower stalks (with more than one bloom) per plant were counted on May 25, 1993.
^wPlants were graded based on a scale of 1 = dead, 2 = poor quality, unattractive, 3 = fair quality, acceptable, 4 = good quality, attractive and 5 = excellent quality, very attractive, on May 25, 1993.
^vMean separation in columns by Duncan's multiple range test, 5% level. Numbers in the same columns with the same letters are not significantly different.
^v*; Results significant at P = 0.01.