Do you know if the temperature of the garage drops below freezing? If so, then it will be risky. If the mulch is on top of a potted bulb, it will not help much unless freezing temperatures are reached for only a few hours at a time. The best would be to monitor temperature and bring them in or provide additional heat when it gets close to freezing. Mulch will slow the rate at which the pot loses heat, but will not keep it warm for long. Mulch works for plants that are in the ground because there is so much heat still remaining in the earth from the previous summer(s). By slowing the rate of heat loss, mulch allows shallow soils to remain at a temperature that is more similar to that of the deeper soil.

I used to do this when I had them in New Zealand and found if your garage is fully closed in you should have no problem's. Try to keep them as far inside as you can to store them.But as said just check what temp your garage area gets to.

I may have mentioned this before but if your garage is attached to your house or a heated building then keeping the pots as close to that wall would be a bit warmer than one of the outside walls. If not than do as Dobbin4 suggests and keep them in the middle, but...isn't that where your car would be?

Our garage is attached to our house and it is at least 10ð warmer than the outside temperatures. You might throw a warm blanket or two on your bulbs on those nights when the temperatures go too low for comfort...and then of course you can always relent and bring them in for the winter! ;-)

Thanks all!

My garage is not used for cars but it is unheated and I just realized that a window is broken. So I don't think mulch will solve my problems of 10 degree winter nights!

I don't want to lose what I spent 3 years growing....
I have a neighbor with a unheated indoor porch which will stay warmer than my garage. They should stay over freezing there hopefully..

What about adding a small electric heater? Can you cover the broken window with a couple layers of cardboard? How many pots are we talking about?
K

It's a 20 gallon or so container jammed with about 15 bulbs.

I already moved them to my friens unheated indoor porch - I hope that will work.