I live in Seattle and made the mistake of not looking at the forecast before I planted my first tubers. I planted 8 dinner plate dahlia tubers. This is my first time planting Dahlias, but I did a lot of research before planting, so I believe I did it properly - however.. the day after I planted, we got literally 2-3 weeks of non stop, 24/7 rain (no hyperbole), it maybe stopped raining for a few 10 minute time frames during the last 2-3 weeks. I definitely should have waited, but our rain usually begins tapering off in April, it just hasnt this year. I havent seen any sprouts coming up from the Dahlias, and I know they were basically planted and then essentially they have been doused with non stop rain for weeks. From all of the research I did, I was supposed to plant them - give them 1 good watering, and then most advice said not to water them again until you see growth. Do you think the relentless, non stop, 24/7 night and day rain for 16 days (and another week coming) has damaged all of them?
Will 2 Weeks of Non Stop Rain a Day After Planting Rot the Tubers?
Certified GKH Gardening Expert
If you are pruning properly, the lack of blossoms could be an issue with fertilizer or with the age of the plants. It's possible that your soil already has sufficient nitrogen, and that added nitrogen is suppressing flowering. You could try adding a phosphorus fertilizer that doesn't include nitrogen.
Here are some general reasons a plant may not flower: