Answer: Your situation is a real challenge! Hyacinth bulbs need 10-12 weeks of chilling at an optimal temperature of 35-48F in order to produce roots. Temperatures below that will retard root formation. Ordinarily we'd suggest placing the styrofoam container near a door that leads inside because the area would be warmer. Having a detached garage complicates the matter. Wrapping in bubble wrap will insulate the container, but if the temperature is below freezing, that won't alleviate the problem. Is it possible to place a light bulb in the immediate vicinity? The heat from a single bulb might be enough to keep the air temperature elevated. An old lamp without a shade would work, as would an automotive work light, hung in the vicinity. If neither of these are available, you may need to set your pots inside your refrigerator in the house. Wish I had more suggestions!
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