With spring on the way, many greenhouse sections and greenhouses are filling up with a wide array of crop types including annual bedding plants, herbaceous perennials, vegetable and herbs transplants, and tropical plants. Many of these crop types will have conflicting environmental and cultural requirements. Almost all greenhouse and retail garden center businesses produce flats or containers with a single-species and hanging baskets and decorative patio planters with mixes of multispecies.
The diverse selection of plant material, containers, and combination planters growing side-by-side for a few weeks like annuals bedding plants or longer-term crops like hanging baskets can lead to growing difficulties that affect overall plant quality and aesthetic appeal. In a recent e-GRO alert, The Ohio State University’s W. Garrett Owen outlines how growers can prevent these difficulties by grouping crops to accommodate their environmental and cultural requirements, which can lead to success this production season.
The main factors to consider include:
- Air temperature: In the hierarchy of grouping greenhouse crops, growers can first start by assessing environmental responses such as air temperature. Greenhouse crops can be grouped into three temperature-response categories: cold-tolerant, cold-temperate, and cold sensitive. These categories are based on base temperatures or the temperature in which a plant stops growing and developing. Ideally, growers should strive to separate crops by their base temperature and grow in greenhouses under different temperature set points. This strategy is advantageous for crop scheduling, lowering heating costs, and maintaining crop quality; however, it may not be feasible for all greenhouse and retail garden center businesses due to space constraints and environmental control systems.
- Photosynthetic Daily Light Integral: Greenhouse crops can be grouped by their photosynthetic daily light integral (DLI) requirements or the integrated measurement of light intensity and photoperiod that plants receive over the course of a day. Under low photosynthetic DLIs, growers can deploy supplemental lighting or retract shade curtains, remove external shade, or remove shading compounds. Under high photosynthetic DLIs, growers can stop supplemental lighting and close shade curtains or apply external shade or shading compounds. In certain situations, greenhouse environmental control systems offer growers the capability to set light thresholds, so lighting and shading is manipulated when outdoor conditions are above or below greenhouse setpoints.
For additional information on substrate and fertilizer considerations, check out the original e-GRO alert here.
What’s Important to New Gardeners? Find Out in This Study