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William H. Carlson

There are over 11,000 greenhouse growers in the United States. Of this number, 8,000 produce less than $500,000 per year in total sales. Less than 1% of the 11,000 have a strategic business plan. Many may have a yearly budget, but they have not developed a formal written analysis of their business in relation to internal and external factors. A sample of 10 growers indicated that their profitability increased significantly when they understood a formal strategic business plan. The information developed from this sample indicates the entire greenhouse industry could benefit greatly from increased use of strategic planning. The marketing component of the business plan and how university personnel can facilitate this effort will be discussed.

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William H. Carlson

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Candice A. Shoemaker and William H. Carlson

Seeds of eight commonly grown bedding plant species [Ageratum houstonianum Mill., Begonia × semperflorens Hort., Impatiens wallerana Hook., Lobularia maritima (L.) Desv., Petunia × hybrida Hort., Pelargonium hortorum L.H. Bailey, Salvia splendens F. Sellow, Tagetes patula] were germinated at pH values from 4.5 to 7.5 at 0.5 increments. Seeds were germinated in petri dishes on filter paper saturated with buffer solutions or in petri dishes containing a 50 sphagnum peat: 50 coarse vermiculite (peatlite) medium moistened with buffer solutions. Germination on filter paper was affected by pH for all species tested. Peatlite medium pH affected germination of all species tested, except Salvia splendens. Species response to similar pH values differed between the two germination procedures. Total percent germination of seeds germinated was less in peatlite medium than on filter paper.

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Candice A. Shoemaker and William H. Carlson

Effects of temperature (18-32C), irradiance (0-4.3 mol day-1m-2), and pH (4.5-7.5) on germination of begonia were evaluated. Germination of 90-93% occurred at 18-24C and 79-83% at greater than 24C. There was no difference in germination between seeds receiving ambient irradiance conditions and seeds receiving 24hr supplemental irradiance (4.3 mol day-1m-2). Begonia did not germinate in the dark. On filter paper, no germination occurred at pH 4.5 or 5.0 while germination of 84 and 94% occurred within the pH range 5.5-7.5. In a peatlite medium, germination ≥80% occurred across all pH levels evaluated.

Photosynthetic photon flux (PPF), day temperature (DT), and night temperature (NT) effects on vegetative development (3 true leaves to first flower) were determined. Plant height increased <2 cm as PPF level increased from 4.4 mol day-1m-2 to 12.15 mol day-1m-2. DT and NT influenced plant height, but as with PPF, the differences were only 1-2 cm. Neither average daily temperature (ADT) nor the difference between the DT and NT (DIF) affected plant height. Primary lateral shoot number increased as temperature and PPF increased.

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Candice A. Shoemaker and William H. Carlson

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Shi-Ying Wang, William H. Carlson and Royal D. Heins

The effect of 6 weeks of storage at 2.5, 5.0, 7.5, 10.0, or 12.5°C in a glass greenhouse was determined on 11 vegetatively propagated annual species. Fresh weight (total, shoot, and root) and height of 30 plants per species in each storage temperature were measured at the end of storage. Another 30 plants were transplanted into 15-cm pots (three plants per pot) and grown under natural light in a 20°C glass greenhouse for 3 weeks. Three species showed chilling injury or died during storage at ≤7.5°C. Plant height and shoot fresh weight at the end of storage for most species increased linearly as storage temperature increased. Storage temperature did not affect the net increase in height or weight significantly during recovery growth, except for plants that exhibited chilling injury at the end of storage.

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Shi-Ying Wang, William H. Carlson and Royal D. Heins

Argeranthemum frutescens `Butterfly' and `Sugar Baby', Brachycome hybrid `Ultra', Helichrysum bracteatum `Golden Beauty', Scaevola aemula `New Wonder',Supertunia axillaris hybrids `Kilkenny Bells' and `Pink Victory', Sutera cordata `Mauve Mist' and `Snowflake', and Verbena hybrid `Blue' were grown in a glass greenhouse maintained at 20°C under seven different photoperiods (10-, 12-, 13-, 14-, 16-, 24-hr, and 4-hr night interruption). Black cloth was pulled at 1700 and opened at 0800 HR; incandescent lamps provided 2 μmol·m–2·s–1 to extend light hours to the designed photoperiods. Seedlings were pinched 3 days after transplant. Responses to photoperiod were clearly species-dependent. The tested species can be classified into three groups: 1) stem elongation and flowering were promoted in the long-day treatment (A. frutescens and S. axillaris hybrids), 2) only stem elongation was promoted in the long-day treatment (S. aemula, H. bracteatum, and B. hybrid), and 3) neither flowering nor stem elongation were affected by photoperiod (S. cordata and V. hybrid).

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Mark P. Kaczperski, Royal D. Heins and William H. Carlson

Methods of cold storage for rooted cuttings of three cultivars of Pelargonium ×hortorum Bailey were examined. Cuttings were stored from 0 to 10°C for 7 to 56 days. Treatments included packing the cuttings in ice, storing them under irradiance levels of 0 or 50 μmol·m–2·s–1, applying fungicides, varying cutting developmental stages, and varying the day temperatures. Cuttings packed in ice showed signs of chilling injury within 7 days and died. Applications of etridiazole and thiophanate-methyl or metalaxyl and thiophanate-methyl drenches or fosetyl-Al spray did not improve storage performance of the cuttings. Roots of cuttings held 7 additional days in the propagation area before storage grew faster after storage than those of cuttings with less time in the propagation area, but flowering time was not affected. Maintaining night temperatures at 5°C while allowing day temperatures to rise to 10°C delayed flowering by 6 days compared to maintaining a constant 5°C. Rooted cuttings held at 5°C under 50 μmol·m–2·s–1 irradiance for 9 hours each day could be stored up to 56 days with only a 2-day delay in flowering compared to unstored cuttings. Chemicals used were 5-ethoxy-3-trichloromethyl-1,2,4-thiadiazole (etridiazole); thiophanate-methyl (dimethyl[1,2-phenylene)bis(iminocarbonothioyl)]bis[carbamate]) (thiophanate-methyl); N-(2,6-dimethylphenyl)-N-methoxyacetyl) alanine methyl ester (metalaxyl); aluminum tris (O-ethyl phosphonate) (fosetyl-Al).

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Mei Yuan, William H. Carlson, Royal D. Heins and Arthur C. Cameron

Most plants have a postgermination juvenile phase in which flower induction will not occur. Some species require a cold period for flower induction and will not respond to the cold treatments during the juvenile phase. We determined juvenile phases of Coreopsis grandiflora `Sunray', Gaillardia grandiflora `Goblin', Heuchera sanguinea `Bressingham', and Rudbeckia fulgida `Goldsturm'. Plants were exposed to 5C for 0, 10, or 15 weeks when Coreopsis had 0, 2, 4, 6, 8, or 10 leaves (>1 cm); Gallardia, 4, 8, 12, or 16 leaves; Heuchera, 8, 12, 16, or 20 leaves; Rudbeckia, 5, 10, 15, or 20 leaves. Plants were grown under a 4-h night interruption lighting (LD) or under a 9-h photoperiod (SD) after cold treatments. Based on time to flower and final leaf count, the juvenility of Coreopsis, Gaillardia, Heuchera, and Rudbeckia ended when they had about 6, 10, 12, and 15 leaves, respectively. Cold treatments were necessary for flower induction of Coreopsis and Heuchera and they increased the flowering percentage of Gaillardia and Rudbeckia. Heuhera was a day-neutral plant, Rudbeckia was on obligate LD plant, and Gaillardia and Coreopsis were quantitative LD plants.

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Mei Yuan, William H. Carlson, Royal D. Heins and Arthur C. Cameron

Scheduling crops to flower on specific dates requires a knowledge of the relationship between temperature and time to flower. Our objective was to quantify the effect of temperature on time to flower and plant appearance of four herbaceous perennials. Field-grown, bare-root Coreopsis grandiflora (Hogg ex Sweet.) `Sunray', Gaillardia ×grandiflora (Van Houtte) `Goblin', and Rudbeckia fulgida (Ait.) `Goldsturm', and tissue culture—propagated Leucanthemum ×superbum (Bergman ex J. Ingram) `Snowcap' plants were exposed to 5 °C for 10 weeks and then grown in greenhouse sections set at 15, 18, 21, 24, or 27 °C under 4-hour night-interruption lighting until plants reached anthesis. Days to visible bud (VB), days to anthesis (FLW), and days from VB to FLW decreased as temperature increased. The rate of progress toward FLW increased linearly with temperature, and base temperatures and degree-days of each developmental stage were calculated. For Coreopsis, Leucanthemum, and Rudbeckia, flower size, flower-bud number, and plant height decreased as temperature increased from 15 to 26 °C.