How cold can my outside girls get without dying?

So overnight low temps are dropping into the high 40s later this week, with daily highs anywhere from mid 60s to nearly 80. I have a nice Blue Mystic around 3ft tall, and a beautiful Northern Lights over 5 feet. Both are flowering pretty good now, and I hope they will have time to finish. I'm worried about the overnight temps getting so cold that my girls won't make it. How low can they go, and what can I do to discreetly try to protect them?

Yer fine down to a hard frost of 28* f. So not till oct 18 and even then growing a green sheet over them works

Joedank said:

Yer fine down to a hard frost of 28* f. So not till oct 18 and even then growing a green sheet over them works

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Wow, they can take it that cold? If I put a couple big lawn and leaf bags over them, will that be enough when there is a frost advisory as it gets closer to October? Do I cover only the greenery, or do I need to wrap the pot they're in too? The Northern Lights is in a 7gal rubber like tub that has only about 5-6gal soil in it. Since its not a hard plastic pail like most 5gal buckets, will it need more insulation from the cold?

manditroy said:

Wow, they can take it that cold? If I put a couple big lawn and leaf bags over them, will that be enough when there is a frost advisory as it gets closer to October? Do I cover only the greenery, or do I need to wrap the pot they're in too? The Northern Lights is in a 7gal rubber like tub that has only about 5-6gal soil in it. Since its not a hard plastic pail like most 5gal buckets, will it need more insulation from the cold?

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You want to protect the vegitation from frost which is what kills the plant material, so you only need to cover the vegetation itself.