A forum for discussion of potential collaborations with regards to ornamentals – i.e. floriculture, nursery crops, breeding, turf, ornamentals industry, botanic gardens, landscape industry, orchids, etc.
Increasing the efficiency of irrigation practices is necessary to conserve water resources. However, extreme reductions in irrigation may lead to stunted growth. In this project, we aimed to evaluate if chitosan applied as a substrate amendment influenced plant growth, physiology, and marketable parameters of container-grown ornamental crops cultivated at different container capacities. The experiment was a full-factorial design with two factors: container capacity (100%, 70%, and 40%) and chitosan application timing (No application, Week 1, Week 3). The plants were kept in the greenhouse for six weeks and then in growth chambers set at 30°C or 40°C for two weeks to simulate post-production conditions. Plant growth and stomatal conductance were measured weekly and flower area after the sixth week. Significant differences were observed between the treatments. Plant growth was lowest at 70% and 40% CC when chitosan was applied at week 3. The stomatal conductance of plants under 70% and 40% CC was higher than 100% CC with no chitosan, but plants with chitosan at 40% CC had higher stomatal conductance. Flower coverage did not differ at the end of the crop cycle and in the first week at the two post-production temperatures (30°C and 40°C), but in the second week, the flower coverage decreased drastically in all the treatments, with the lowest values observed at 100% CC in both environmental temperatures. Deficit irrigation in petunia plants could be a strategy to produce marketable plants while reducing the volume of water. Chitosan applied in the first week of production seems to be the best application timing under deficit irrigation to see an amelioration effect from lowering container capacity.
Overwatered spring crops are subject to a range of biotic and abiotic disorders including hypoxia, nutrient deficiencies, and increased susceptibility to root rot diseases. Defining parameters associated with under- and overwatering would demonstrate how watering practices influence growth and abiotic disorders that develop during greenhouse production. Growth and nutrient content of petunia ‘Cascadias Indian Summer’ (IS) and ‘Headliner Strawberry Sky’ (SS; Expt. 1) and calibrachoa ‘Aloha Kona Midnight Blue’ (MB; Expt. 2) plants were grown under three different watering regimes of overwatered (rewatered when weight of sentinel pots dropped to 90 to 95 5% of container capacity, CC), optimally watered (60 5% of CC), and underwatered (35 to 45 5% of CC) and two different fertilizer sources of Jack’s Professional General Purpose and Jack’s Classic Petunia Feed. Across both plant species, the optimal watering regime generally yielded the largest plants based on width, fresh and dry weights. SPAD readings of youngest foliage were different based on fertilizer source. While IS petunia did not develop yellowing of youngest foliage in any treatment, SS petunia developed distinctive symptoms of interveinal chlorosis in youngest foliage of overwatered plants fertilized with general purpose fertilizer. However, tissue analysis of SS petunia revealed no difference in Fe between watering regimes or fertilizer formulations. Differences did occur across watering regimes in tissue P, K, Ca, Mg, S, and Mn and between fertilizer formulations in P, Mg, and S. Overwatering induced visual symptomology of chlorotic young foliage in SS petunia and MB calibrachoa, but not IS petunia, which suggests a genetic component to the disorder. Symptomology is effectively mitigated by using petunia feed. Tissue nutrient content is affected by overwatering, but Fe is not significantly different. Future work will explore a mechanism associated with substrate microbial activity that explains these results.
Sugarcane bagasse (SCB), a byproduct from the refinement of sugar, is an abundantly available material in tropical and semi-tropical regions. The use of SCB as a component in soilless substrates and other horticulture applications has gained attention due to its regional availability, use as a peat alternative in floriculture production, and as a phosphorus-rich material. Phosphorus (P) is an essential element for the growth of plants; however, P leaching losses from excessive fertilizer applications can pose environmental concerns. This study evaluated using SCB as a soilless substrate amendment in the production of Petunia ‘E3 Easy Wave Coral’, where two particle sizes of SCB (hammermilled at 4 mm and 6 mm) were blended with a peat moss/perlite (7:3 by vol.) floriculture media at rates of 15% and 30% by volume. Two fertilizer rates were investigated, one applying P at 100 mg L-1 and one applying P at a reduced rate of 30 mg L-1. Plant growth and vigor was assessed through measuring growth index (average of plant height and two widths) and chlorophyll content (SPAD). Leachate collected from containers following the “Pour-Through” method was assessed for pH and electrical conductivity (EC), with subsamples collected and analyzed for nutrient content. Plants appeared to grow larger in the control (peat moss/perlite media only) and 15% SCB amended soilless substrates compared to the 30% SCB substrates, regardless of SCB size or fertilizer rate. Substrates amended with SCB at 30% resulted in less vigorous growth than either the control or the 15% SCB amended substrates; however, the differences were less visible in the 30% SCB media when provided the higher P fertilizer rate. Given the important role of P in plant growth and the environmental concerns associated with fertilizer applications, evaluating P availability in sugarcane bagasse and its potential contribution to plant nutrition could provide a more sustainable alternative for soilless substrate systems in floriculture production.
In high latitudes (≥40°), commercial greenhouse growers utilize supplemental lighting (SL) and heating to offset low solar radiation, air average daily temperature (ADT), and root-zone temperature (RZT) during peak young-plant production. Growers have historically used high-pressure sodium (HPS) lamps to deliver SL but are transitioning to light-emitting diode (LED) fixtures, mostly because of their improved energy efficacy. However, many growers report changes in crop morphology and undesirable purple leaf pigmentation when cuttings of some species, especially petunia (Petunia ×hybrida), were grown under LEDs. The objectives of this study were to 1) quantify how light intensity during callusing, ADT, RZT, and SL sources influence the morphology, rooting, leaf pigmentation, and quality of petunia and to 2) develop strategies to mitigate the purpling of leaves. Shoot-tip cuttings of petunia SureShot ‘Dark Blue’ and ‘White’ were inserted into 72-cell trays and propagated inside a greenhouse at an air ADT of 21 or 23 °C and with an RZT of 21 or 25 °C. Cuttings were grown under SL delivered by HPS lamps or LED fixtures proving different light qualities (low blue or moderate blue) at a photosynthetic photon flux density of 60 or 120 µmol·m–2·s–1 for the first 6 d, then 120 µmol·m–2·s–1 for the remaining 16 d. Cuttings of both cultivars grown at an air ADT of 23 °C often had greater stem lengths and shoot dry masses than cuttings grown at 21 °C, as well as lower concentrations of anthocyanins. Cuttings of both cultivars grown with an RZT of 25 °C typically had longer stems than those grown with an RZT of 21 °C. Overall, cuttings of both cultivars propagated under LEDs were of greater quality (shorter stems, greater root dry mass) than those grown under HPS lamps. The color of cuttings grown under LEDs were more red and blue than those grown under HPS lamps, especially at low ADT and RZT. Additionally, the anthocyanin content of ‘Dark Blue’ cuttings grown under LEDs was greater than those grown under HPS lamps. Little differences were observed between cuttings grown under either LED fixture. These results indicate that growers using LEDs may have to adjust other environmental parameters, such as light intensity, ADT, and RZT, to produce cuttings of similar morphology and quality to those grown under HPS lamps.
Photo-selective shade nets substantially benefit ornamental plant production by mitigating excessive radiation, enhancing light diffusion, and promoting adequate ventilation. These nets establish favorable microclimates that optimize water utilization, thereby reducing plant water demand through physiological and environmental adjustments. Shade nets of different colors vary notably in their spectral distribution and light transmission characteristics, directly impacting plant morphology, physiology, and development. This study aimed to evaluate how different colored photo-selective shade nets influence physiological, morphological, and floral characteristics, as well as water usage, in Zinnia elegans ‘Cherry Queen’. We used four distinct shade net colors: blue, red, white, and black with 30% shade factor as treatments. The 107 cm x 61 cm shade structure was prepared using the PVC pipes with different colored shade nets wrapped around it. Seeds of zinnia were sown in a commercial substrate, Metro-Mix® 820, and kept on a misting bench. Following germination, the plugs were transplanted in a 3.6 L pot filled with the same commercial substrate and kept under four distinct color shade nets. Substrate moisture content was consistently maintained at 35% volumetric water content using an automated irrigation system using capacitance-based soil moisture sensor, ECH20 10HS from Meter Group. Black shade nets transmitted the least radiation across all wavelengths. Blue shade nets increased transmission in blue and green wavelengths while reducing red and far-red light transmission. Red shade nets enhanced red and far-red wavelength transmission, whereas white nets provided the highest overall radiation across all wavelengths. Morphologically, plants grown under red and white shade nets exhibited similar growth and floral characteristics to those under blue nets, and all showed improved growth compared to plants under black nets. Physiological responses, including photosynthetic assimilation rate, stomatal conductance, chlorophyll fluorescence (Fv/Fm), Soil Plant Analysis Development (SPAD), Normalized Difference Vegetation Index (NDVI), and anthocyanin content measured via leaf spectrometry remained similar across all treatments. Water use per plant was highest under white shade nets, significantly exceeding usage under black nets but comparable to blue and red nets. Growers may prefer red or white shade nets for optimal growth and water efficiency, blue for balanced spectral quality, or black for reduced radiation needs.
Maryland’s cut flower industry represents an expanding sector within the broader U.S. horticultural market, currently valued at $6.69 billion with Maryland alone contributing significantly ($139 million in 2018). Recent surveys conducted at the 2025 Bay Area Fruit School and University of Maryland Eastern Shore, Small Farm Conference-2024 provided critical insights into the demographic diversity, interests, and barriers faced by Maryland cut flower growers. Survey results indicated a diverse population, with participants spanning various ages, experience levels, and farming backgrounds. The largest demographic segment (25%) ranged between 35-44 years, suggesting an active, economically productive age group interested in cut flower production. Notably, the survey underscored a strong existing interest, with half of the respondents expressing a high level of enthusiasm toward cultivating cut flowers. Despite this enthusiasm, significant barriers impede growth and expansion. Key limitations identified included a lack of expertise and technical knowledge (41.7%), limited availability of relevant workshops and training (33.3%), and restricted market access (37.5%). Other reported challenges comprised high production costs (29.2%), pest and disease management issues (25%), limited labor availability (20.8%), and environmental factors such as weather variability and soil conditions. Dahlias emerged from these findings as a particularly promising crop, offering distinct advantages for Maryland farmers, especially those with constrained resources. Due to their delicate blooms and brief vase life, dahlia imports into the U.S. are minimal, primarily limited to pompon varieties. This creates a substantial market gap and an opportunity for local growers to supply diverse, premium-quality blooms tailored to consumer preferences. Consumers increasingly favor locally grown, sustainably produced flowers, especially when sourced directly from local farms, enhancing market potential for dahlias. To enhance dahlia production in Maryland, growers should consider collaborative research trials and evaluations of variety selection, sustainable cultural practices, and integrated pest management strategies under varying conditions, including open fields and protected cultivation such as high tunnels. Developing specialized extension materials, hands-on workshops, and practical demonstrations can also significantly address existing knowledge gaps. Such focused, region-specific guidance and facilitation of access to lucrative markets would empower Maryland's small-scale growers to capitalize fully on the growing demand for locally produced specialty flowers, significantly enhancing their productivity, profitability, and long-term sustainability.
