Ed, When dormant they are good down to probably 10 degrees anyway. On occasion here in Florida it gets to the lower 20's and I have never had any damage to them from it. Granted that is several hours at that temperature and they are dormant now week after week of cold not sure what their damage point would be.

Digdirt, hit it. Plants vary. I don't consider it "stunting". Plants will wait until the right temperature/light cycle to take off, as long as they are not damaged. Or just search "cosmos cold tolerance" (example) for each of your plants. One site says cosmos will tolerate 35 degrees. The link below doesn't really pertain, but you can find similar that might. A lot of studies have been produced on the matter. Bob Here is a link that might be useful: frost tolerance

What I do now is keep them in my cold attic, right by a window sill. Temps get into the 30's, but I've never seen any water freeze. Do you have an unheated garage with a window? No garage or attic, I live in a teeny little house! The coldest part of the house is the kitchen floor, it's like ice when it's cold outside, but I don't want to risk him getting too warm and I worry about my devil cat eating him if he's on the floor in there. She mauls my little baby Violets enough as it is, I'm surprised I have any survivors to give away for x-mas! :) I do have an unheated metal shed in the yard, but no window, I think that would be just the same as being outside, but without any sun! :P So far I've been bringing him in whenever it looks like it's going to get under 30 degrees. That's been working great, in at night, out during the day. I guess I'll leave him in the fridge today, surely one day won't hurt, it's supposed to be 33 and sunny tomorrow so I will set him back out then, and they're calling for warmer temps for next week, so he should be able to get out every day. J

You folks kinda "frost me" with a bit of jealously ... because I'm just over the climate cliff, with a solid week of 22 F already this season. Hopefully it's over for winter. (Worst I've seen in last 15 yr is 17 F.) I'm in z8b with cool PNW summers. So I'm currently forgetting anything outdoors with limbs and am testing 1' plant base "stubs" with cold frame protection this winter. At 22 F outside it did not freeze inside at ground level. Next year plan to also try just dry fallen leaves and top tarp to save stubs. Also testing a whole main limb structure stored in our ~40 F garage along with backup cuttings, which I will soon start. Below is 'Frosty Pink' vs 'Little Angel' on the the day before the first hard freeze. It started with a heart breaking "wack em down" step. This was in late Nov with a few prior weeks of below 45 F night temps. BTW the 'Frosty Pink' cutting had finally got big enough above the Y to have its 2nd flower flush. 'Little Angel' in contrast had been blooming since mid summer and still was pumping out, now less full, flowers on the talker stem, with head more exposed to cold breezes. Compare with lower flowers on the backup plant. Note plants more green during the summer. They are cold stressed here (click photo, they're not quite that stressed). BTW this location is my Wife's favorite late summer "hammock spot" l, with these two Brugs at the footend. One poor 4.5' 'Little Angel' tub test is also currently in the garage, in the dark, and not being watered. Essentially leafless now, but with healthy fat stems ... it's pumped out a few half sized flowers in the dark! Past year photos. Another LA cutting from this same plant in a tub planter, in August. BTW this LA only received 3-4 direct summer sun midday in this location. This is a cool forested yard in Woodinville, WA. A lawn chair here put next to this tubbed plant placed that top leaf leaf node at hair level ... yep, my evening "Incense(d)" area. LA grows fast and has a flower or bud at every node, with staged nodes always visible for the next 2 to 4 flush cycles. She also throws a few flowers between flushes. So once it starts LA is always in bloom for us. "Floral attack*" gets exciting from mid summer onwards ... with 2, 4, 8, 16, 32, 64 ... but I've not yet made it further outdoors before frost, when starting from a same year cutting. LA is a VERY nice fragrance plant so you need to strategically place that lawn chair to get just the right exposure. Truly mind boggling when you want it! My style. (Should it be legal sitting that close without a license?) I saved a few nice cuttings for trades.