Growing annual phlox can be frustrating. I get questions about their germination on a pretty frequent basis, and I often feel bad that I can’t offer more exact information about the process. Like many other flowers, I didn’t start trying to grow phlox until after I had started using the winter sowing method. Using containers, or using a low tunnel, I am able to achieve some really great germination rates.
As far as I’ve been able to discern, I believe that these are yet another one of those flower seeds that really benefits from alternating cold and wet temperatures. This is the perfect recipe for success using the winter sowing method. I’m beginning to wonder if the process of germination is even stumping some seed suppliers –
This season, I received a package of cherry caramel phlox from Baker Creek. It was marked as being over packed , due to low germination rates. I winter sowed the seeds at the end of January. It is now mid February, and the seed tray in the low tunnel is absolutely bursting with life. It is quite clear that the actual germination rate for these seeds was much higher – I’m not complaining.
I’ve been working on trying to get the “best bloom” from this flower for a couple seasons. While I’ve never heard that these plants have any tolerance to frost, I’m starting to suspect it and may even try to overwinter some annual phlox in the garden this coming fall.
Have you had luck over wintering your phlox?
Phlox seed doesn’t have a long shelf life, either (I’ve read 1 year). I suspect that a lot of germination issues are due to people using old seed (I’ve had this issue before). But, I also had a lot of success winter sowing (with fresh seed).