Potted plants are taken into the greenhouse in December or January after having some good cold weather outside.
I get asked quite often how I handle my seeds. You have to remember, I do all of my hybridizing and starting seeds in the greenhouse. With that in mind, here is how I handle things. Plants are potted in August/September and held outside until they have had enough cold temperatures to grow quickly in a greenhouse environment. Normally that takes place in December or January. In 2008, I started taking them into the greenhouse in the middle of December. Plants are cleaned, Marathon 1% is used to control fungus gnats, thrips, aphids, etc. I use Nutricote slow release 13-13-13 fertilizer with micro nutrients along with a little Milorganite for fertilizing. I also water with a weak solution of water soluble fertilizer each time I hand water. The greenhouse is kept at 55° at night and gets much warmer during the day in the sun. I will start seeing scapes at about 2 1/2 months, and bloom about 3 weeks later.