I know the answer to this!!!! I am soooo excited!!!!! :D :D :D Ok, milk. You want to dilute the milk so it is about 10-20% of what you have, definitely less than 30% or it will make something else bad that you don't want to happen happen, and spray it on every week or two (don't do it too often or the plants will be unhappy), and this will prevent a lot of powdery mildew. It is more of a preventative measure but you can try it if you see just a little, well, you might as well try it when you see a lot, but it's better to start before you see it at all. This is probably the only answer I will ever know, thank you so much :D

Neem Oil (the brand I posted) was recommended to me by Armstrong Garden Center as an effective way to control powdery mildew in an organic garden. It does not harm bees, as long as you follow instructions and spray at night. It is most effective when used at the first sign of the mildew. It has no apparent effect on the ant population as far as I can tell, just the mildew. For me, it has been used with good results on all types of squash leaves, with butternut seeming to like it almost as nourishment.

While there's clearly a lot of research in your post Jeannie7, the answer you're providing michiman is, well, pure bunk, IMO. That a plant has been grown in a zone does not make it native to that zone...it may make it hardier to that zone, but Dahlias are native to Mexico (zone 11), not the Pacific North West...so pretty much all Dahlias in NA are growing outside their native zone, by 2 or more zones. Weve got posters from zone 4 who have blooms. Dahlias do not produce bulbs, which are stem tubers, they produce root tubers which are significantly different. I seriously doubt that the tubers michiman received from his FIL were "hybridized" for the Pacific North West. Whod want such a plant? Whom would you sell it to, where would you show it? If it wont grow in trial gardens around the country, it cant get its ADS designation (AFAIK.) So unless FIL is genetically engineering some very specific Dahlias, and totally forgot they were hybridized for the PNW and gave them to michiman in order to prove his daughter made a bad choice of husbands (knowing that michiman would never be able to grow them in Michigan) I seriously doubt the tubers are the source of the problem. This is further proven by the fact michimans tubers sprouted, and some flowers do appear. Clearly these are viable tubers IN MICHIGAN. Which part of michimans growth tells you they **cant** grow in Michigan? This isnt to say that the PCN isnt a great place to grow Dahlias, but its not the only place for any varieties Ive ever heard of. Ive got 43 varieties of PCN grown tubers growing here in my zone 5b garden. My point is that this whole zone hardiness bunk is misleading to anyone who might believe you. As long as you can provide a long enough growing season for your Dahlias, whether that is partly inside or not, you can have beautiful blooms practically anywhere. My average from 95 blooming plants right now is ~160 days from the time you take a tuber out of storage to the time it blooms. The quickest was 107 days, the longest 230, so as you can see there can be a huge variation even in the same gardens (as someone else pointed out, there can also be a huge variation in the soil composition/sun/water across a single garden.) Michiman, my best suggestion to you for next year is to take your tubers out of storage any time after mid- January. Stand them up in some soil so the pointy end of the tuber is in the ground, and push them in about half the length of the tuber. You can put them 4"-6" apart. Watch the eyes form (if they hadnt before you divided them) and sprouts form. When the sprout is ~4" long, or has 3 or more sets of leaves, cut it off very close to the tuber. Put that cutting in a 4" pot with Miracle Grow Seed Starter mix. Water thoroughly and keep watered until you see new growth (remember, these arent tubers any more so you cant really hurt them with too much water.) Grow these in your windows, rotating as needed (to keep the stems straight.) In May, when all chances of frost are gone (air frost, now youll be worried about the leaves being frosted so this is a little later than youd worry about frost for tubers,) plant them out in your garden as you would tubers. Leave them in their pots, or take them out...your choice. Leaving them in the pots will make for smaller more compact tuber clumps in the fall and theyll be easier to lift. In all other respects theyll grow identically either way. You should have blooms much earlier this way, regardless the variety. Cheers, Russ

It would have been good to treat them with a fungicide while they were growing, but I wouldn't worry about it. Perhaps dunk the tubers in a mild bleach solution before storage to kill the spores on the outside. One experienced grower hypothesized that powdery mildew compromises the storage quality of the tuber, but that's hit-or-miss, and you can't do much about it if that is the case. I had extreme problems last year with PM, and sprayed every month for it to keep it in check this year. It only presented itself at the end of the season, when the plants were struggling before dormancy.