Hi Grace My answer may not help you at all but... I live in Sf and have grown dahlias out in the sunset for years (which is one of the worst environments for growing flowers) and in my opinion, you are causing more work than you need to for yourself. I NEVER have started my dahlias indoors, I never have dug them up for overwintering and I rarely even touch them after they bloom in year one. And I (just being honest) have a yard that is the envy of my friends and neighbors. Even in heavier rain years, I never worry about my tubers and in years like this, I find I have to go out and water in the winter in order for them to get ANY moisture. Do I lose dahlias? Sure do. But not often and usually only when I am lazy and allow the snails to have at em when they start sprouting. But if I lose a few (out of 90+ and counting), it gives me an excuse to buy more tubers the next year! You may well grow beautiful dahlias with all the dedication you are showing but for my money, it is much ado about nothing. Dahlias are hardy and once they get used to their environments, they last forever. And you know well in the sunset we get up to 2-3 months of NO SUN and heavy fog. So if I can grow beauties with little maintenance, I am sure you can also. If you prefer the high maintenance route, go for it. But I think you will find it a full time job because there will ALWAYS be something - mold, rot, lack of water, too much water, snails, too much heat (sun), not enough heat, freezing temps, long foggy months, staking, and maybe , just maybe, the tuber was no good from the get go DESPITE what you do! Good luck. And if you live in the sunset and want to see my yard some time, I have dahlias from May to November but the best month is August. Come on by!

Are the worms IN your tubers or just around them? In any case, if it were me, I would rinse them off, dust them and isolate them for a while. Without a photo, I couldn't even guess what they are. Good luck.

To keep from loosing your dahlia locations...it is suggested that you plant a stake at each one when you plant. All but the miniature varieties will need staking up later as they grow, so by putting in a stake even a small one when you plant you will know exactly where to put a taller sturdier one when they get up several feet high, without impaling the hidden tuber as you stake it. After many frustrating years, I now also bury a plastic tag with the plant name along with the tuber, so when I go to dig it up after its dormant I know which one I am diving and possibly giving away tubers to. A label just stuck into the ground by it will be pulled out by chickens, crows, children, dogs, ets. Been there, done that! Last year was teh first year with 4 chickens in my garden. They pulled out all 160 labels and flung them as they were scratching for bugs! They also unburied the tops of the tubers. THis year they are no longer allowed in there when the dahlias are growing!

Love opposing views. I have been storing dahlia tubers in plastic bags for over 20 years now and I do not seal the bag so there is some air getting in there and my success rate is outstanding. I store several thousand tubers each year. Not only do cardboard boxes wick moisture but they also can rot when they they get moist and can cause rotten tubers. And I have heard of very many people having their entire crop of tubers eaten by mice that chewed through the cardboard boxes. I experimented with the potting soil and put my best tubers in it. They stored much worse than those in vermiculite and sprouted in storage weeks before the others. Sprouting while in storage is not good. Potting soil is not a good storage medium. I would use nothing at all in preference to potting soil. Swan island Dahlias uses no storage medium and places their tubers into plastic tulip crates that are lined on the top and bottom with sheets of newspaper. There success rate is pretty good and they store several hundred thousand tubers each year. However, they have a dedicated potato root cellar for their storage facility and the temps an humidity are ideal. Off gassing does not occur in plastic bags at any rate that hurts tubers if you use vermiculite in the bag and/or you dry the tubers before storage.