That's incorrect and I can GUESS who posted that pH number... grr... just one more reason I'm glad he's on vacation.
Soil pH range is 6.5-6.8.
Get your minimum temp up to 65.
FLUSH those plants well with water adjusted to pH 6.8 to bring your soil in range.
Those skinny leaves look to me like cold +too wet + too acidic = plant is not able to uptake nutes properly. You're in a flush-or-die situation! Fluuuuuush!!!!!