Snug in its glassy igloo, the cardoon slumbers peacefully through the winter. Although the leaves die back, the plant reawakens in spring to grow with a vengeance. Protecting larger plants, especially those with woody stems, requires a little more ingenuity. For anything under 15 inches, I carefully bundle the branches together and cap them with a large, overturned, plastic pot covered with leaves or pine boughs to ward off heat on a sunny day. Plants that are larger require a custom approach.
Coddled plants can look intriguing.
Ever since I saw a Euphorbia characias ssp. It's nowhere near hardy here, but I figured a little protection might go a long way. The first winter, my protected plants died, but I attributed that to winter wetness, and amended the soil to improve drainage. The next fall I surrounded a new plant with bubble wrap wound around four stakes and stapled into place. For a roof, I tied stakes to the pillars as rafters and topped it off with a sheet of plastic.