Carencia, sobre fertilizacion o quemadura por frio?

Unless your on Antarctica or the Sahara desert they should be fine :D Most deficiencies are a result of overwatering, killing the roothairs in the proces. Even dumping in loads of calcium and magnesium wont do the trick. GL!

I would check run off ph first and make sure you are in range for proper growth. If so some cal mag and potassium will stop spotting. Leaves won't repair themselves.

Yea 13° is about as cold as you can go without killing them. If you're mid-flower, that could also be PK deficiency.