Look at these photos of my angel trumpet (Brugmansia). Two days ago, it was big and lush and bright green like the photo on the left. Yesterday morning, the poor thing looked like the photo on the right – all pooped out. Today, it’s even more pooped out. What’s happening? Blame the cold.
While angel trumpets are subtropical plants, my garden’s temperatures dip well below freezing in January and February, despite being only a few miles from the beach.
In the 32 years I’ve gardened here, I’ve learned which plants manage the cold and which get damaged by the cold, then pop right back in spring. Fortunately, angel trumpet bounces back. But in the meantime, for a few months it looks really sad.
Notice how the top-most leaves look the worst, while the lower leaves don’t look too bad? The top and outer leaves are most exposed to the cold, while the lower and inner leaves are protected by the upper branches and nearby plants.
This is why I tell gardeners to leave all damaged plant parts until spring. Those outer leaves and stems damaged will protect the lower and inner leaves and stems from the next round of cold temperatures. So just leave them in place.
What's happening here?
Remember how water freezes when it expands? It’s why you leave space when filling ice cube trays or freezing containers of juice, soup, and other liquids.
Leaves are typically 80% to 98% water. In freezing temperatures, water in and around leaf cells form ice crystals and expand. That disrupts the structure of both the cells and the leaves. As the day warms, the water thaws and escapes. The leaf dehydrates and collapses, hence my angel trumpet’s sad looking leaves.