Is it helpful to soak Dahlia tubors in water before planting? If so, for how many hours?

Hi there,

I don't recommend doing this at all, as water encourages rot, plus dahlia tubers are not like tulip/daffodil bulbs. Just plant them in soil and go from there.

Thank you, it's our first time planting them (and we're getting a little bit of a late start, but still plenty of time for a good show in later summer and fall). With good sun, about how many weeks do you think it would take from tubors to flowers?

Depends on the variety, smaller ones can bloom in about 8 weeks, while larger ones can be 12-16 weeks.