Rex Begonia - How to make them happier?
I have several Rex Begonias (all noids) for about 1 1/2 years that I grow in a north window year round in a bright room (north and east windows total about 14 feet tall and 20 feet in width so their area has a lot of light but no sun at all) There is no central air or A/C so during the summer they are generally the same temperature as outside in PA and during the winter it ranges from 68 to 72 day/night. Average natural humidity is high in summer since the windows are open, usually 70% is the lowest, in winter the average natural humidity is 60% -70%.
Last winter I kept them growing in the same soil they came in, they didn't go dormant but did lose a few leaves. Late this summer I repotted all of them in box store african violet soil since I wasn't sure what to use. I water them when they are starting to be a bit dry about 1/2 inch deep - usually once a week, sometimes a little longer depending on season. I fertilize weekly with Schultz African Violet liquid fertilizer in late spring, summer and early fall, no fertilizer in winter.
Here is an example of 2 of them. They aren't doing poorly, yet they aren't doing well either. None are excited to be alive, they are just living. I'd assume that after this much time they would have developed better growth. Does anyone have suggestions how to make them a bit happier? More/less light? Different potting soil (is now a good time to repot?) Different fertilizer? A great website information link? Thank you :)