You probably haven't really given enough pertinent info for the vets of this board to answer your question so I'll ask the obvious:

Were they 1st year dahlias? Did you get them from neighbors, an online vendor, garage sale or from a box store? What was your watering schedule? Did you prepare the soil and what was there before them, if anything? Are slugs and snails evident in your yard? (And did you mean NO repeat blooms?)

If the soil was good and the watering sufficient - then to have 5 out of 10 not bloom tells me the tubers were not that good to begin with. But that would be the LAST reason - I suspect the soil has too much acid in it from pine (fir) needles and that sufficiently poisoned the ground. Especially if they did not repeat bloom.

Cnote, you said, "They all grew tall, had buds that wanted to bloom, but it didn't happen." What happened to the buds? Did they disappear, turn into a slimy mess, wilt, fall off, blacken? Pictures might help us. :-)

Is it possible that what you thought were buds were actually the seed head of the earlier flowers? Perhaps a deer came by browsing hungrily?

Thanks both for the follow up!

The tubers were all purchased from Dan's Dahlias. I've never had an issue with growing from there before. The only difference this year is that I made a box to place in my yard- it gave them a couple add'l hours of sun each day. I had no slug troubles, and being in the city I don't have to deal with deer.

As for the repeat blooms, not one single plant had add'l blooms after the first 1-3 flowers died off. BUT, new buds formed and eventually blackened- just the buds, no surrounding leaves on the plant.

I'll see if I can get a decent pic, but my plants took heavy damage recently from the outrageous rains we received recently

Look something like this?

I've noticed a dozen or so blackened buds in the last week. Not sure why, but it is not a problem at all for me, as there are many MANY more buds that are just fine.

So sorry that is happening to you! Perhaps extreme weather shift? I have no words of wisdom for a solution to this problem.