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Plants suitable for extensive green roofs must tolerate extreme rooftop conditions, and the substrates in which they grow must fulfill horticultural and structural requirements. Deeper substrates may retain more water for plants during dry periods, but will also weigh more, especially when near saturation. A study in central Pennsylvania was conducted to evaluate the influence of substrate type and depth on establishment of five green roof plants. Two stonecrops [white stonecrop (Sedum album) and tasteless stonecrop (Sedum sexangulare)], one ice plant (Delosperma nubigenum), and two herbaceous perennials [maiden pink (Dianthus deltoides) and saxifrage pink (Petrorhagia saxifraga)] were planted in three depths (30, 60, and 120 mm) of two commercially available green roof substrates (expanded shale and expanded clay). Study flats inside a plasticulture tunnel received three drought treatments (no drought, 2 weeks early drought, and 2 weeks late drought). The two stonecrops performed well under most conditions, although tasteless stonecrop was stunted by early drought. Ice plant only grew well when provided with water. When subjected to any drought, the herbaceous perennials had the fewest survivors in the expanded shale. Saxifrage pink flowered profusely wherever it survived. The study plants were most affected by substrate depth, except for maiden pink, which responded solely to drought. When subjected to early drought conditions, the herbaceous perennials did not survive in 30 mm of either substrate, or in 60 mm of expanded shale. Although the stonecrops performed well in 60 mm of substrate when subjected to drought, their performance was superior in the expanded clay compared with shale.

Green roof construction is constrained by cost of labor to install the plant material. Optimizing seed germination and establishment could significantly reduce installation costs but would require specific growing conditions that are difficult to provide during installation. Plants of the stonecrop (Sedum) genus are commonly used for the roof top because they will tolerate the high temperatures. This study compared the germination rates of four stonecrop species {goldmoss sedum (Sedum acre), ‘Oracle’ sedum (Sedum forsterianum), blue spruce sedum (Sedum reflexum), and amur sedum [Sedum selskianum (synonm Phedimus selskianum)]} at two temperatures, 70 and 90 °F, following storage of seed in dry, cool (40 °F) conditions of different durations (54, 98, 157, 197, 255, or 343 days). At 70 °F seed of goldmoss sedum, ‘Oracle’ sedum, and blue spruce sedum produced minimum germination rates of 60% at 21 days in seed stored for 54, 98, 157, 197, 255, or 343 days. Goldmoss sedum, ‘Oracle’ sedum, and blue spruce sedum showed reduced germination in 90 °F, probably due to temperature-induced dormancy. Amur sedum had germination of at least 83% at 21 days in both temperatures tested. As amur sedum germination rates appear to be unaffected in the temperatures tested, it could provide an excellent seed for use on green roofs where ideal temperatures are rarely available.

A set of studies was established in Summer 1998 to determine the tolerance of field-grown cut flower species to specific preemergence herbicides, the effectiveness of weed control by those materials, and to determine if productivity of cut flowers is affected either by the herbicides or by colored mulches. Pendimethalin provided excellent early season weed control, but poor late-season control. It consistently caused injury at 4 lb a.i./A and sometimes at the 2 lb a.i./A rate. Oryzalin provided good to excellent weed control, but slightly injured celosia and zinnia when applied at 4 lb a.i./A. Napropamide provided excellent early season weed control, but marginally acceptable weed control later in the season. Though napropamide caused some injury to celosia early in the season when applied at the high rate, no injury to any of the plants was observed later in the season. Prodiamine and trifluralin were the overall safest of the herbicides, but they provided the weakest weed control. OH-2 was very effective when placed on the soil surface, but was less effective when placed on an organic mulch. The organic mulch was designed to keep the OH-2 particles from splashing on to the crop plant and injuring the plants. OH-2 tended to be safer placed on a mulch than on the soil surface, but statice was slightly injured even when a mulch was used.

The Internet offers many new and unique opportunities to disseminate information. The development of the World Wide Web (WWW) and information browsers like Netscap, Mosaic, and simple-to-use server software like MacHTTP provides means to allow low-cost access to information, including pictures and graphics previously unavailable to most people. The Pennsylvania State Univ. variety trial garden annually tests >1000 plants. Information is gathered on garden and pack performance, and photos of superior plants and varieties are taken. To provide wider access to this information, we have begun development of a Cyberspace trial garden on the internet. This server contains a wide variety of garden trial information developed from trials conducted in State College and Dauphin, Pa.. This server and a similar effort at Univ. of Minnesota are being constructed cooperatively. Hot links are provided between the server in Pennsylvania and the one in Minnesota, providing users with seamless access to information from both servers.

The dramatic reduction in available greenhouse insecticides and the potential for increased insect resistance has necessitated a change in insect control techniques. Because of the large acreage of greenhouse production in Pennsylvania and the need for a more environmentally effective method of controlling insects in greenhouses, an aggressive Integrated Pest Management research program was initiated and has been on-going since 1989. Our objectives were to develop a bibliography of major insect pests; to determine effectiveness of parasitoids on greenhouse and silverleaf whitefly, western flower thrip, and aphids; to reduce pesticide usage; and to comply with worker protection standards. The program was implemented by a joint venture among the Pennsylvania State Univ. faculty and technical staff, grower cooperators, the Pennsylvania Dept. of Agriculture, and the Pennsylvania Vegetable Growers Association. The IPM program was started with an active scouting and monitoring program in commercial houses to determine threshold levels. Control measures were implemented with biological controls, cultural management, and lastly chemical. In addition, the implementation of the results of this research to commercial growers has resulted in the formation of a Greenhouse Crop Management Association. Results of the 5-year research program are discussed.

Gardeners can provide the best insight to their gardening experiences and interests. In order to identify potential buyers of the state plant promotional program, Pennsylvania Gardener Selects (PGS), an intercept survey with 243 participants was conducted at the Philadelphia Flower Show on 6-7 Mar. 2003. Objectives were to better understand Pennsylvania consumer's: current gardening related shopping habits; where they obtain gardening information; and their motives and limitations for pursing gardening. Responses were analyzed to identify potential consumer segments who might purchase PGS plants. Participants with an income >$50,000 (55%) are more likely to gather their gardening information from a university website than those with an income <$50,000 (39%). Respondents with a college education (59%) reported that time was the limiting factor when gardening as compared to those with only a high school diploma (44%). Survey responses were also analyzed using Cluster Analysis, which generated three distinct consumer segments: “Novice Gardener” (consumers with limited experience in gardening), “Non-Gardener” (consumers who prefer not to garden), and “Avid Gardener” (consumers who spend the majority of their leisure time gardening). “Avid Gardeners” are likely to purchase plants evaluated for Pennsylvania (average response of 6.5; scale 1 to 7) and 73% have purchased Pennsylvania products. They also are more likely to purchase their landscape plant material at local nurseries/garden centers (82%) than the other segments (68%). Based on the results it can be assumed that “Avid Gardener” could be a potential market for PGS plants. A marketing strategy for reaching this audience may consist of promotions at local nurseries/garden centers along side other Pennsylvania-grown products.

Two separate studies using intercept survey methodology were conducted to define the components of a state plant promotional program—Pennsylvania Gardener Selects (PGS)—based on consumer preference and appeal. The first study, conducted 6 and 7 Mar. 2003 at the Philadelphia Flower Show in Philadelphia, Pa., involved 243 Pennsylvanians. Objectives were to define current gardening-related shopping habits, sources of gardening information, motives and limitations for pursuing gardening, and history of purchasing other Pennsylvania products. Responses were analyzed using cluster analysis to identify consumer–gardener segments that would potentially purchase PGS plants. Three distinct consumer segments were generated: “Novice Gardeners” (consumers with limited experience in gardening), “Casual Gardeners” (consumers with limited confidence in their gardening knowledge), and “Avid Gardeners” (consumers who express great interest in gardening). “Avid Gardeners” exhibited a greater level of interest in purchasing plants evaluated for Pennsylvania (average response, 6.5; based on a scale of 1 to 7, where 1 is very unlikely and 7 is very likely), with 73% indicating that they had purchased Pennsylvania products; hence, they were a potential market for PGS plants. The second study, conducted 8 to 10 Mar. 2004 at the Philadelphia Flower Show involved 250 Pennsylvanians. Objectives for this study were to define consumer brand and product preferences, including container colors for the PGS program, plant tag style/color, and retail price (based on a scale of 1 to 7, where 1 is very unlikely to purchase and 7 is very likely to purchase), as well as brand attributes these consumers valued. Responses were analyzed using conjoint analysis. Participants awarded the highest utilities to the white container with a black-and-white PGS logo (0.1149), keystone-shaped tag with color image and PGS logo (0.1099), and a retail price of $1.98 (0.4751). Spearman's rho was used to identify relationships among existing and related brand attributes. Correlations between participants’ response to brand attributes, including locally grown, ideal for local conditions, quality assurance, and independent testing program, as well as plant guarantee and publication with gardening tips, suggest that promotional materials should emphasize and include these qualities. Results from these studies indicate that there is interest in a state plant promotional program for Pennsylvania. To use resources wisely, consumers classified as “Avid Gardeners” would be the most appropriate to target first. To attract consumer attention and encourage purchasing at a retail outlet, containers and plant tags should have distinctive colors, and brand attributes and resulting consumer benefits should be emphasized on promotional materials.

A consumer-research study was conducted in two locations in Pennsylvania utilizing two survey methods: intercept and telephone. This study was designed to assess: 1) what national brand name plant material participants purchased in the past; 2) the consumer's awareness of the Pennsylvania Gardener Selects (PGS) program; and 3) the gardening habits and demographics of Pennsylvania gardeners. The first survey was an intercept survey of 390 self-selected participants who attended Ag Progress Days (APD), a 3-day outdoor educational event and farm implement show from 20-22 Aug. 2002. The second survey was a telephone survey of 500 randomly selected households in the metro-Philadelphia area and was conducted from 20 Aug. through 17 Sept. 2002. Only responses from Pennsylvania gardeners were used in the analysis of the results. A comparison of survey results indicated that metro-Philadelphia-area participants spent more on plant material annually than APD participants, who primarily resided in rural locations. The results showed that metro-Philadelphia-area gardeners tend to live in single-adult households and have one or more children, whereas APD gardeners tend to live in a household with two or more adults and have no children. Eighty-one percent of APD participants and 62% of metro-Philadelphia participants reported that they would be willing to purchase plant material that has been evaluated and chosen as being outstanding for use in all areas of Pennsylvania, a premise for the PGS program.

Abstract

Lateral shoot growth and plant morphology of poinsettia (Euphorbia pulcherrima Willd.) were influenced by the pinching technique used for apical meristem removal. Plants were pinched in one of four ways: 1) soft (removal of the apical meristem plus stem and leaf tissue associated with leaves ≤2 cm long); 2) medium (removal of the apical meristem plus stem and leaf tissue associated with leaves up to 7 cm long); 3) hard (removal of the apical meristem plus stem and leaf tissue associated with all immature leaves); and 4) leaf removal (LR; soft pinch as defined above plus removal of all immature leaves but not the associated stem tissue). Initial growth of lateral shoots on soft and some medium-pinched plants was less than initial growth of lateral shoots on hard- or LR-pinched plants. Shorter lateral shoots and longer primary stems at anthesis on soft-pinched plants resulted in vertical plant architecture. Hard- and LR-pinched plants had a more horizontal plant architecture. The average height : width ratio of soft-, hard-, and LR-pinched plants at anthesis was 0.77, 0.68, and 0.63, respectively. Of 10 commercial cultivars tested in 1987, 48% of the inflorescences of soft-pinched plants developed below the bract canopy, compared with 27% and 31% for hard- and LR-pinched plants, respectively. These results show that the use of a soft pinch to increase inflorescence number in the bract canopy is not productive if immature leaves are left on the plant when pinching.

Abstract

The effects of photosynthetic photon flux (PPF), day temperature (DT) and night temperature (NT) on leaf number, leaf unfolding rate and shoot length were determined for chrysanthemum (Dendranthema grandiflora Tzvelev. ‘Bright Golden Anne’) grown under short day (SD) conditions. A functional relationship was first developed to predict if flower bud appearance would occur within 100 SD under a given set of environmental conditions. All combinations of DT and NT in the range from 10° to 30°C were predicted to result in flower bud appearance at higher PPF than 10.8 mol·day⁻¹·m⁻². The number of leaves formed below the flower increased quadratically as DT and/or NT increased from 10° to 30°. As PPF increased from 1.8 to 21.6 mol·day⁻¹·m⁻², one to two fewer leaves were formed per shoot. Rate of leaf unfolding increased linearly with increasing average daily temperature from 0.2 leaves/day at 10° to 0.5 leaves/day at 30°. Internode length was highly correlated with the difference between DT and NT (DIF = DT – NT) such that increasing DIF from –12° to 12° resulted in progressively longer internodes.