Aren't orchids surprising? Sometimes nothing you do for them seems to suit and they turn their little roots up and die. Others, you can ignore and they will happily go on living without you! I have been using time release fertilizer pellots with a higher nitrogen content. Cyms really seem to be heavy feeders. I give each plant one teaspoon of three month time release pellots every TWO months. They like tall skinny pots so I put them in plastic lemonade pitchers. The smaller ones in a two quart size and the larger ones in a gallon size. The handle makes the heavy plants a little easier to pick up and move around. What will the temperature in the cold frame drop to over the next few months?