It has been such a horribly slow year for our dahlias. We went to a large dahlia garden and it was the same way. By now, they are usually in full bloom. Can someone explain exactly what happened this year since it seems it wasn't just me? We had a very wet and cool June and an unusually hot and sunny July. Is one of these or both of these an issue?

The hot, dry July was the issue plus it was a cool May.
I am in SE Michigan and mine were growing fabulous until the heat stared. Once it did, buds dropped, buds aborted, flowers got smaller and didn't last very long. This is my second season growing dinnerplates and I figured that the heat was the issue.
Now that the weather has changed for the better, they are growing like crazy, branching and making buds all over. It went from 68-74 at night to 58-64 degrees and the days went from 90+ to around 80!
Dahlia friendly weather you could say.

Dahlias always do horribly where I live. They only really bloom for us in mid-late spring and early fall. I imagine it's like what @BigBill was describing. The hot nights here do almost everything I plant, dirty. Tomatoes stop producing, peppers struggle, impatiens take a break, many annuals just stop growing, and dahlias are sadly a part of that list, too. Interestingly, I know of places that have 100+ degree days for weeks, but have cool nights. Their dahlias bloom still. Hot nights are just a plant's worst enemy.

Isn't it strange they are native to Mexico where it is hot as heck then!? This is confusing. And of course there's no way to protect from any of it. I guess one just lives with good years and bad years.

It's hard to get a feel for dahlias since it seems no two years are alike. We had a cool, wet spring and I was still planting some of mine well into June, 2-3 weeks later than normal. Then came the heat and they wilted so much during the day that you'd swear they were goners. But every morning they were always perked back up. Cooler nighttime temps give them a chance to rebound. During hot, stressful weather I give mine a good morning soaking at least twice a week. In 2017, I had more July blooms than ever before. This year I have some that will be lucky to bloom by late September, if at all. Who really knows why? Maybe certain weather conditions just throw off their timing. I keep hoping for a year of "normal" dahlia weather but have forgotten what that's like.

Dan. Great evaluation!
I agree completely. I have experienced that same thing here this year.

I built a list of 374 heat-tolerant dahlias that was compiled from multiple lists...

https://garden.org/lists/view/...

Personally, I have found a few hours of light morning shade to be pretty helpful.

Do any of you have to dig them up and store them for winter?
This would be my 1st time i own dahlias, they look awesome btw. =D
TnksInAdvn.

I do (and I'm in zone 7) and am sure most of us dig and store tubers over winter.

Dahlia 'Alfred C'

Yes! They will never make it if you don't dig them up in zone 6a.

Totally agree!!

Jilllove said:Yes! They will never make it if you don't dig them up in zone 6a.

...hmm any suggestions on how-to?
My 1st time storing cannas went horribly. Lost bout 50giant canna bulbs

This is a loooong story. I suggest you google it and read everything you can. That's what I did in the beginning. But wait until a hard frost kills them. Then cut the stalks down. I leave enough to hang onto to pull from. Then loosen soil around root tubers with a pitch fork and gently remove the ball of tubers. Wash them really well. Get all the dirt off. Let it dry. May take awhile depending on the weather. Then there are a ton of methods to store them. I've tried 3 different methods and am still undecided on the best one.

If you go back a page (page 2) on this forum, there is a short thread titled Digging and Storing Dahlias, 2018. Everyone approaches it differently, depending on their situation and what works for them. A few of us chimed in there with our methods.