Getting Fall Garden Mum Propagation Right
Getting Ready for Propagation Season
Summer is in full swing, and greenhouse growers across the country are receiving their garden mum cuttings for fall production. If you've already gotten your shipments of unrooted cuttings, or are anticipating them soon, now is the time to ensure your propagation environment and practices are dialed in. These reminders will help you get your cuttings off to the best possible start.
Pre-Propagation Checklist
Sanitation
Before the cuttings arrive, thoroughly clean and sanitize the propagation area. Shut off misting systems to allow any algae or debris to dry out for easier removal. Clear out any leftover plant material, weeds, or debris from benches, floors, and mist nozzles. The space should be free of pests, diseases, and contaminants that could affect rooting.
Supplies
Take inventory of your propagation supplies like trays, substrates, rooting hormones, and surfactants. Ensure you have enough stock to avoid shortages mid-propagation. Test the initial substrate pH and soluble salts [referred to as electrical conductivity (EC)] to identify and correct any issues before sticking cuttings.
Disease and Insect Pest Management
Develop a strategy to prevent and manage potential disease and insect pest problems during propagation. This could include prevention, scouting, chemical controls, or biological controls depending on your operation.
Optimizing the Propagation Environment
Misting
Once cuttings are stuck, begin misting. Adjust misting intervals as callusing and rooting progresses – too much mist can inhibit rooting and cause rot or stretching. Discontinue misting once roots are established.
Lighting
Aim for a daily light integral (DLI) of 10 to 12 mol·m–2·d–1 by using shade curtains or whitewashing greenhouse glazing as needed, especially in summer. High DLIs during propagation will produce higher quality rooted cuttings, but too high of light can become detrimental. Supplement with photoperiodic lighting to provide long-days or night interruption.
Temperature
Maintain air and propagation substrate temperatures of 70 to 72°F for optimal rooting. Shading can help manage temperatures in the propagation area.
Monitoring Rooting Conditions
During propagation, routinely check substrate pH and EC using extraction methods like:
- 1:2 Extraction
- SME
- PourThru
- Plug/Liner Press
For fall garden mum liners, keep substrate pH between 5.8 to 6.2 and EC below:
- 1.5 mS/cm–1 (1:2 Extraction)
- 3.3 mS/cm–1 (SME or PourThru)
By following these cultural and environmental guidelines, you'll give your fall garden mum cuttings the best start for developing a healthy, vigorous root system. Proper propagation sets the stage for a successful finished crop.
W. Garrett Owen
Assistant Professor of Sustainable Greenhouse and Nursery Systems, The Ohio State UniversityW. Garrett Owen is an Assistant Professor of Sustainable Greenhouse and Nursery Systems in the Department of Horticulture and Crop Science at The Ohio State University. He has an appointment in research, teaching and Extension. His area of expertise is plant nutrition; plant growth regulation; and production problem diagnostics.
