My kale survived the cold snap. Both at "the garden" (above) and next to my house (below). I didn't cover either.
Below is at the garden. I've been picking leaves from the bottom for months. Next fall I will plant more kale. We love it.
I planted two varieties of kale and both survived.
The above bunch doesn't look so good but it will perk back up as the temps rise.
Below are mustard greens that didn't make it.
I need to give all my boxes some fertilizer as the nutrients wash out of these raised beds quickly.