Yes you can do that but why? Unless they are special wax begonias (variegated, double, rare) I'd treat them for what they are sold as - annuals.

If you do overwinter then provide bright light and you should do okay. Spray for mildew as it arises and watch the water - they need to dry out some between watering unlike most other begonias.

I grew them from seed and they never really flowered very well. don't know if it was the soil or mulch that effected them. was going to transplant them in sterile soil as a experiment to find out. thanks for the input.

Go for it. I've done it but the results are not what I wanted - often dying back and then growing and getting mildew and dying back, etc.

I think bright lights will make a huge difference if you can provide them that. I kept mine under a shop light and think they needed more light to thrive.

was going to keep them at 70 deg. and on a timer for 8 hrs. a day.think that will work?

I keep my timers on 12 hours but you could try 8 to begin with.

don't they like 10F temp drop at nite?

Do they?

that's what i remembered. here stated nite 60-65F, day 70-75f
http://www.thegardenhelper.com/wax_begonia.html
when grown as houseplants.
outdoors there's always a temp drop.
another site even said they need cool nites 52F to 65F days to do well. many others just say 70-75 - presuming daytime? it probably depends on the your zone too.
i know we had this discussion with you, hcmcdole, before:).
i don't do wax begonias, but my non-stops positively perked up when it dropped to 60-65F at nite and now close to 55f nightly they are just thriving. but may be that's different...since they are tuberous hybrids? the temp info is all over the place, confusing.

I really don't keep up with temps or swings. I would expect a normal range of temps for us to be comfortable indoors is good for most houseplants too (at least to get through the winter months).

I don't do wax begonias either - too fussy for indoors typically and takes up valuable space that could be used for harder to come by begonias and houseplants. I have wintered over double wax and Charm a few winters. I overwintered B. 'Big' this past winter which is wax like but is much larger than the common bedding wax begonias. But then 'Dragon Wings' and 'Big' are readily available the past several springs at most nursery centers for a nominal price.

Tuberous do have their quirks - probably why the west coast can grow some of the very largest flowers. Another begonia I don't grow due to its demanding care requirements.

You can get an idea of what two 'Big' plants can do in one summer. They are in an 18" container behind an equally large container of alocasias/colocasias. One of my 80+ pound dogs is in front by a couple of feet.

this is some giant begonia! .black with heart-shaped leaves? this BIG???.....oops! i think it's a calo ;))...
the dog looks reticent - doesn't approve of paparazzi?
and finally...the big begonia is red flowers on the left, out of focus? very hard to see. kinda like dragon wing?

Yep, dogs are usually not that interested in sitting still.

Yes, the begonias with red flowers behind the elephant ears are called Begonia 'Big' for obvious reasons.

Out of focus because I focused on the dog and wanted some blur in the background. (subject should be in focus, right?)

Here is a close up of the same begonia but not the whole thing because it is now behind a wire enclosure to keep excited dogs OUT.

nice color contrast and dark bronze? leaves. the enclosure is clever and rather good looking too ;).

I wasn't sure if the original goal/question asked was because there is no room by a window, or it was assumed these plants would be unattractive if brought inside for winter? In a bright, sunny window, wax Begonia is a great plant to have inside, blooming all winter when I've given them such a space before. Is that an option?

They are perennials here, but not all plants live through each winter, not reliable unless the roots can outgrow the peat ball from the 6-pack, so I'm usually breaking off stems to save from frost too, those are goners for sure whether the roots grow new foliage the following year or not. I can't 'break'n'stick' stems as fast as dogs step on them in this yard (I don't have time to get into the visiting dogs situation, in which case measures that work in regard to our great Dane are often useless, so I'll just say I have a definitely skewed opinion of saving Begonias and a Begonia quantity panic mode in general.)