It is very possible that the stalk may develop new shoots if you left it fairly long, the junctions where leaves once where (they look sort of like ridges) may have active growth nodes inside. I have a dahlia clump that amazingly survived severe neglect in the fall prior to my getting it. I have just planted it 3 weeks ago, and it has 4 buds. 2 are from the tubers themselves (well, actually just above at their necks where they join the stem) but 2 are actually on the old woody stem piece that was left. To my somewhat untrained eye, I thought the stem was dead! But obviously it isn't! lol. I plan to take sprout cuttings in a few more weeks from these stem shoots, but, that is another conversation! If you where to dig out the tuber, you would likely find lots of smaller tubers attached to the stem. Interestingly enough, you cannot just break off these tubers and expect them to turn into new plants. It is very near the base of the stem where the eyes, or new shoots develop. Each tuber, needs some stem that is producing at least one eye to develop into a plant! A root that is broken off without an eye, will put out roots, but no foliage! However, I have a feeling you are talking about looking for growth on the stem further up, like where it had leaves last year. This is what I am saying, yes, you may get some new growth from the places where the leaves joined the stem. But... in the spring I would carefully uproot it, and divide the clump, carefully making sure each tuber you take off, has a shoot or eye (growth node). Generally, the fewer tubers you have on the clump, the better the plant. If the plant has a huge clump, it sees its job as being done, and does not have much insentive to grow big and put out flowers. If you don't do this, then at the very least, limit the number of shoots that you allow to continue to grow. don't allow all the tubers in the clump to send up or at least keep shoots up.

A commercial grower should always ship dahlia tubers with visible eyes and you were correct in requesting replacements. Size of the eye or the tuber (unless the tuber is too big) should not be a factor. Any tuber with a visible eye should grow when planted but that is not always the case. Quality of the tuber is not always known due to virus, growing conditions from the previous season(s) and many other reasons that are unknown. Some of them just rot or won't grow even though we do every thing correctly. I plan on needing replacements in my garden based on a number of reasons and always have some plants growing in pots to use and I always need some of them each growing season. Selection of a commercial grower to purchase dahlias from is important and can only be learned through trial & error and that is not always foolproof. I purchased a new release this season from a very reliable commercial grower and it ended up having virus (it didn't look right from the start) and I pulled it up and threw it away. I have found, in the few I have purchased, that tubers from big box stores don't always match the name or picture on the package and there is no recourse. I always purchase named dahlias that I know will do well in our heat here in the South. There are a number of commercial growers that provide excellent tubers/cuttings that I would be glad to recommend to you in a separate email.

Its worth a try, you never know. Sometimes adventisous buds will develop from the energy stored in the tubers, Wait at least two years to see what happens from a normal planting. Al

Potting soil is normally a mix of peat moss, perlite or vermiculite, lime and a wetting agent. The perlite/vermiculite provide drainage and keep the peat from compacting. The lime brings up to a neutral pH, as peat moss by itself is normally on the acidic side for most plants. The wetting agent forces the peat moss to absorb moisture... I make my own potting mix, and use a dab of dish washing soap with warm water to moisten the mix. Without some kind of wetting agent, dry peat moss is a nightmare to hydrate. I don't use sand in my mix- over in Europe (where our friend Lin is located), using sand is standard practice. Sand provides drainage but does not keep peat moss from compacting like perlite/vermiculite does. Regarding a 'warm spot:' Room temp is warm enough- don't use a heating mat! That is overkill, and might cause your tubers to cook! Sunlight is not needed until the tuber sprouts, so the plant doesn't 'stretch' for any available light. If you have it outside, beware rolly pollies, snails and slugs, who might eat the sprout before you even see it. "I was once told it was ok to break off the stem as it will re-grow but yesterday at a tuber sale I heard a club member saying not to break it off." It's okay to break off long nasty sprouts, allowing a nicer one to grow from the tuber. Plant that long nasty sprout in a pot, moisten the mix and stick a baggie over the top for 10 days until you see new growth in the cutting, then take the baggie off. If the tuber's sprout is nice, go ahead and plant with it attached... no worries either way.