My winter windowsill is too cold for S/H phals
 

I've helped my plants limp through the Massachusetts dim winter with supplemental lighting, and things are starting to grow again. I have a Phal. hieroglyphica that's been in S/H for a couple of years but hasn't bloomed. I have a move coming up the end of the summer and wanted to see how difficult it would be to get my plants out of their jars. They have lots of slimy algae but I've never worried about it. I coaxed my P. hieroglyphica out of its jar easily, only to give a mass of routed roots. It's growing healthy new ones at the top, but the roots that were deeper in S/H were all rotted. I keep the house at 60 or above, but i think it was just to cold this winter in the windowsill. My carts are all fine. They have roots to the bottom of their jars that are nice and solid and white. My phals that suffered this winter will recover, but now I know I really do have to bottom heat the phals here. Fortunately, my wife is taking a job in L.A., and even if I can't give a job there this year I'll surely be there next year! My phals will be so much happier there (and so will I)!

The reason I had to stop using bark was for the same reason. The temperatures by the double-glass sliding doors were just too cold and the bark would never dry out completely in the middle and the roots would all rot. This year, I moved the orchids under lights and wintered over a pom. tree, two figs and a citrus by the doors. Now I understand how people can grow orchids in bark. :|

That's the key for Phals in S/H in a Northern climate- seedling heat mats work great, btw.

At what point should I be using a seedling mat? I'm growing on a windowsill in Oregon, temps in summer in my house not dropping below 60 F at night, but with the evaporative cooling....

Use a heat mat when temps drop below 60. I've seen narrow ones (designed for windowsill applications) online before.

Thanks Marc!