- Author: Susan Croissant
I still have not cut back anything in the garden because although temperatures "appear" to be rising, where I live, we're not quite past the danger of overnight frost. Just a reminder, you still have until around Valentine's Day to cut back your roses, so don't stress on that.
As I said in my January blog, frost is water vapor freezing on the surface at a temperature of 32˚F or below, forming tiny ice crystals when the water vapor condenses. Frost injury occurs when these tiny ice crystals form on the leaf surface, drawing moisture from the leaf tissue. Thus, dehydrated plants are vulnerable. Keeping them watered helps to protect the roots and warm the air near the soil (water gives off heat, damp soil retains heat better than dry soil).
I have two Salvia leucantha (Velvet sage or Mexican bush sage) in my front yard. The one nearer the street is more susceptible to wind and cold and always has a tougher struggle. They have been surviving the frost quite nicely, thank you, both hanging on pretty good through this cold spell while I was watering once a week. I had not watered the last three weeks plus there were continuous overnight frosts. Alas, both Salvia's finally bit the dust.
On the bright side, this has happened a couple times before. I'll do the same thing I did then--cut them back (once the danger of frost has completely passed). They WILL revive and thrive, as you can see from these photos taken AFTER I lost them the last time. Some advocate cutting it back every year anyway. http://www.morningsunherbfarm.com/product_info.php?products_id=335
Meanwhile, the Lavandula dentata (French Lavender) hasn't missed a beat during these frosty nights and, indeed, appears to have thrived.
Again, check this website: http://ucanr.org/sites/sacmg/Frost_Protection