As you gain experience, you'll be *better placed* to decide which need "planted out", and which might need a bit more TLC, but, with a bit of extra care.....they all can be planted in the garden. here's my method.
For 'freshly dug" rhizomes.......maybe a week, out of the ground, *probably" given a bleach water dip when they were dug, I give them a quick dip in 10% bleach water , ONLY if I suspect there might be a problem (i.e. obvious insect, or disease damage to the rhizome), and by "quick", I mean , maybe 2 minutes. Then, they go into a bucket of water, to which I've added a dose of Miracle Grow ( 1 tablespoon to 2 gallons of water), where I let them soak (some soak only the roots, and don't let the rhizomes or leaves get submerged...I soak the whole thing !) for an hour (approximately ....a minimum of 1/2 hour, surely, and a maximum of 10-12 hours). When I prepare the planting "hole", I mix either alfalfa pellets, or meal, into the soil.......i.e. I dig a hole 4"-5" deep, and wide, throw in a handful of pellets, rake about half the soil back into the home, and give it a good "stir" with my trowel........how many roots, and the condition of the roots will dictate whether they can be spread out into the hole, and then "back-filled with the remainder of the soil, or, whether (in the case of "almost no viable roots"), you just fill in the remainder of the soil, and rake up enough surrounding soil to make a small hill, maybe an inch and a half higher than the actual soil level, and place the rhizome. In the case of 'no roots (or very closely trimmed roots") you will need to either 'pin" the rhizome to the ground (landscape pins, pieces of coat hanger wire, bent into a candy cane shape) or have a small rock to sit on top of the rhizome to hold it in place) . I sprinkle a very small amount (1 tablespoon) of 5-27-5 fertilizer around the rhizome (try not to actually get it in direct contact with the rhizome. Water the area well (I use the water/ Miracle Grow mix that I used for soaking), and move to the next one !
In the case of very small, very dry, or really damaged rhizomes, the onlyb thing that really changes, is I *may * give them all a 10-12 hour soak, and plant them in pots, using the "lightest" potting medium I can get...mixed with a small handful of alfalfa, watered in with the same solution of MG, and then the pots are placed in a "mostly shade" situation ( or, "filtered" shade) until I see signs of new growth, then into a sun situation , for several weeks, then into the garden.
In the ground, or in the pot, I keep the rhizome watered.....when the top 1" of soil is dry, I water......in hot , dry weather....that may be every day....when signs of growth are seen.....you can stop watering as often.
There are as many methods as there are gardeners, and the trick is to find what works for you, in your dirt, and climate....and, what fits your schedule. Good Luck !