You can over-winter the canna tubers the same way you would your bananas but the coleus has a fibrous root system and is usually grown as an annual in the colder zones. If you really want to keep the coleus going you can take some cuttings. You can buy a cheap grow bulb and keep them inside. The color will fade but the cuttings should easily root and will rebound when they go back out next spring. Unless there's something really special about that particular coleus I'd let it die. You can buy them for a couple dollars in the spring and they grow fast.

karyn is right colues have to be grown all winter. You cannot store them. I wish it was easy to buy colues in my area. I am going to put a couple that I found this year in a old fish tank and see if I can keep them alive this winter. They like humidity and the fish tank light will help with the light requirements.

I wish it was easy to find different coleus every year instead of the common ones you grow from a little seed pack or....This year every place I went all I saw was some huge ugly coleus with the worst colors I have seen in a long time. I refuse to pay a arm and a leg for shipping and 5 bucks for a little plug.

I do not know why the nurseries do not carry the different colues or why all of them insist on purchasing the same one that everybody is selling. I think it is that Kong Series. I do not mean to offend anyone that liked the one that was sold this year but it really was not my taste. There are so many gorgeous coleus out there but the local nurseries do not order them.

Earthworm, the cannas will be fine in the ground for winter in 8b. ..Unless there are cannas that are not as hardy as others?

Coleus can be saved as cuttings in bottles or jars of water on a windowsill.

Good for you. I hoped to get some cannas cheap at the end of the season too. They are one of my favorite plants. I have over wintered them many times, it's easy. I live in zone 5. Based on the other gardener you could plant them.

OR

Take out of pots, wash them off, minamally seperate them until planting in the Spring. Just let the water do the work. Store them in a box with peat moss that is slightly dampened. Check them periodically and mist the peat. You can use other mediums to store the tubers. Newspaper, sawdust, but no more than two layers.

The only other thing I could suggest for the Coleus is to use a Humididome. Take one node cutting if space is an issue. Fill out a flat full of your favorite cuttings, put water in the bottom of the flat and cover with the humididoam. Place on a warm surface, or store between 73-75 degrees.
You may also put soil in that flat, dip cuttings in root hormone, use a dibber to make a hole in the sole, put cuttings in, cover with humididom, place in warm location or under a light for extra warm, not direct sun though. In about three weeks you can tug on them and if you feel resistance you got roots. Of course you can check on them anytime.

Cannas go dormant during the winter either a. if the temperature is low or b. there is insufficent water. If neither of these occurs they will continue to grow and even flower during winter. It is a lot of fun to take some cuttings in fall and keep them warm and wet throughout the winter. Though they will need a lot of sun to flower durring this period they make good foliage plants, esp. the purple-leaved and variegated types. - Ian.