I started off my Begonias on March 6th and 13 of the 20 have sprouted with varying degrees of activity! But the remaining seven show no signs of growth. They are all in the same position, on a warm tray of moist compost on a windowsill above a radiator in an upstairs room. The temperature is about 68 degrees Farenheit. None of the tuberous corms has rotted (they were all stored correctly through the winter). I have grown tuberous Begonias many times and never had such a dismal success rate. Any ideas??
Why Have My Begonia Corms Not Sprouted
Certified GKH Gardening Expert
Since it can take some time for these plants to sprout, I would give them a little more time. They may simply be slow to start this year. Also, you may want to check the corms to ensure that they are still firm - even if they were beforehand, something could have gone awry and now causing issues.