Both Seattle and Procyon are in the 3-4' range, depending on feeding levels, sun amounts (full sun will give fuller dahlia), water amounts, and so on. Excellent care can cause both to exceed their normal maximum heights and flower more, of course.

Dahlia absolutely require about six hours of direct sun per day, so make sure your indoor location features that. I raise mine outside in my south to west garden where mine receive nine to twelve hours of sun. The mailbox garden dahlia gets sun from sunrise to sunset.

Post-planting, it usually takes about 2 months for the first bloom, but it varies a lot by the individual tuber. I've gotten flowers from my dahlia (Blue Boy and Sun Lady) in as little as five weeks. On the up side, dahlia are in full swing in late summer and early fall when the rest of the garden is getting a little tired.

Number of blooms varies widely by care regimen, plus the larger-blooming dahlia tend have fewer blossoms per plant at any one time. The Seattle, with 8" blooms, is likely to have fewer blooms at once than the smaller-blooming Procyon at 4". Anything from four to fifteen blooms at once is well within the normal range.

There are exceptions. My Color Spectacle can outdo the Blue Boy, featuring fifteen six-inch blooms at a time while the Blue Boy has eight four-inch blooms.

But again, sunlight levels are directly related to blooming strength. If your indoor locale is short on sunlight, the dahlia will bloom poorly, if at all.