Frigid temperatures may have some growers wanting to pulling energy curtains. However, if you are beginning to propagate young plants in the next few weeks, you will want to maximize the amount of light available to plants and increase daily light integral (DLI; cumulative measure of light intensity during a 24-hour period), if possible. For future, keep these low light months in mind. Try to keep your glazing material clean (and free of snow), change your old plastic, and if you have it, utilize high-intensity supplemental lighting.
Here are some fact sheets and resources on lighting:
How low can you go? Low daily light integrals impact young plant quality and production time by Michigan State Extension
Scroll down for more links to articles about lighting
Photoperiod and Bedding Plants, University of Mass Extension
Supplemental lighting webinar (or pdf slide show), Roberto Lopez, Purdue University, e-Gro
Tina Smith, UMass Extension and Leanne Pundt, UConn Extension
