What potted plants do you have? How many and how big?
Its not just the cold...plants need light too...most garages do not have very many windows...if any and it will be too dark....if you want to save them they will need to come inside. If space is an issue move some thing else from inside to the garage ( like an extra chair of sofa) and give the plants a warm well lit space.....other options are to donate to people who have the room for them.
About 30 plants total. Perennials like abelia, leucantha, mexican petunias, gardenia , etc. There are windows. Loaning them out is a great idea. I'd like to keep them here. Can I wrap them with something?
You can create a mini greenhouse type affair in your garage. Make a fort out of mulch bags or straw bales as close to the windows as you can, put heat mats underneath the pots. cover the fort with plastic. Remove as temperatures moderate. You will need to monitor as the temps go up and down. Also bottom heat will dry your plants out faster. http://www.greenhousemegastore.com/category/seed-starting
Some people use low watt lamps, but due to liability, I am not advising such. I certainly don't want you to burn your house down for 30 plants!
Your gardenias would probably withstand the cold. But, do this for all your plants in a pinch...
* Group them all together with just a little space between each.
* Use shredded paper that you can probably get from businesses and offices if you don't use a paper shredder at home.
* Spread them LOOSELY around & over the plants.
* Do NOT squish them up. You need air in between for insulation.
* In my opinion... don't worry about the lighting factor. You want them hibernating not actively growing. As long as they have moisture, you want the roots to thrive/survive 'til Spring.
* Encouraging growth will weaken the whole plant structure.
* BE Careful about using anything like straw, hay or even mulch; you don't want to introduce foreign bacteria, fungus or mold. Besides, in any garage... it INVITES critters.
Oh... BTW, Good Luck and happy planting in the Spring, Brad!
How about a space heater the kind that uses a bulb instead of a heating coil. (for safety) and plant lights. Hope the electric bill isn't too high...LOL
I have some what the same problem. I put my plants in my husbands shop if the temperatures are in the 30's to low 40's. If they are in the mid 40's are above I bring them outside. Anything below 25 I am fortunate to have a sun porch that I make room for them for a few days. Wish there was room for them all winter on the sun porch.
For years Anne has rooted camellia cuttings in styrofoam coolers, with a transparent plastic cover, and left them outdoors for the winter in Raleigh, NC. If it is a plant that you would normally be growing outdoors it is fairly easy to make a small cold frame and cover it with clear plastic. If you have a garden you can submerge the pots to protect the roots and make a frame to fit over the area to keep it warmer and provide light for the plants.
I like the cooler idea
I do too.
Make a light stand by taking a metal shelving unit and hanging strip fluorescent lights with chains on underside of shelves. The lights can be adjusted up as plants grow and the heat from lights will keep them warm during very cold temps.
you might try a pvc pipe type green house.....covered in heavy gauge clear plastic and halogen light (s) for warmth, w/ full spectrum florescent for growing. the green house can be broken apart if not glued, and stored for next winter- , also fatigue mats- those foam play mat type things that hook together in 2 ft x 2ft section, will keep cold from coming up from the floor, and they are ok with getting watered.
Well maybe I got lucky but a hosta which I started in a pot has survived 2 winters. As well I have a tiger lady that I potted up last fall and it has been growing all winter. Both of these are in my garage and I live in Ontario Canada.