Question
Hello Jim. Thank you for your recent answer. A lot has changed since that time. Flasks finally arrived and last Saturday I placed them in pots. I use electrical blanket to warm propagator and installed little fan inside for air circulation. The problem I faced already twice is the following: two days after potting I saw firs symptoms of grey mildew (I think). Kind of a hairy , grey mould between pieces of medium, pretty similar to the one that appears on bread. I sprayed all plants with solution of Physan 20 in proportion 2tsp/1gallon of water. I thought the problem disappered but apparently not. Today (2 days after spray) I noticed that mildew again. I sprayed again making the solution a bit stronger. What could cause that problem? Is it humidity? An average 80-90% in my propagator. Maybe the temperature? Min 19'C/ max 29 'C. I know that I should reduce a bit humidity but I don't want to expose them to the room atmosphere without preparing them first. What should I do? I would appreciate your help. Best regards, Agnieszka.

Answer
Hello again Agnieszka,

You are correct in that the very high humidity is the probable cause for the grey mildew.  If possible, try to reduce the humidity to around 50% and be careful of watering, especially the amount and frequency.  What you want is the potting mix to be moist but not wet.  If you can, try keeping the propagator lid slightly raised (about half inch to an inch) to help reduce the humidity.  If you can control the amount of heat from the electric blanket, keep it on the lowest setting as what you want is warmth not a hot house in the propagator.  Also, there is no need to raise and lower the temperature within, just keep them warm for now.  About 2 to 3 weeks before you plan to remove them, start raising and lowering the temperature (19C to 25C) to get them acclimated for the outside world.  

If the mildew problem continues, you might think about repotting them into fresh mix.  One of the problems with spraying is that it only treats the leaves and top surface of the mix only.  

Hope this helped.  Good luck and have fun!  

Jim Kawasaki
San Jose, Ca.