We have attached a presentation we recently hosted Webinar style about Energy Efficient Poinsettias and the Cold Grow technique. Please take a look as it may answer some of your questions about dropping temperatures. Since you are concerned with mid season varieties this information may provide useful information in the planning process for next year but it will also give you an idea of what type of delay you can expect by reducing your temperatures further. With all the questions about color development we thought it would be helpful to add our new Poinsettia Bract Meter to the discussions. The Bract Meter features 5 varieties with a set of pictures with plants at varying stages of coloring up. You can reference temperatures and the images and get an accurate picture of how much time you have until the plants are ready for sale. You can also program the crop if you know when you need the plants to be ready by referencing the images and the corresponding temperatures you will know where your temperatures need to be to make that sale date. The Bract Meter is printable and makes a great tool in the greenhouse!
