The first year they self seed they form a low rosette of thick, grey/green leaves about 25 cm in diameter and in their second year they grow a tall flower spike up to 2m tall covered in primrose yellow flowers. The plant then sets seed and dies. They are biennials rather like foxgloves (Digitalis) in their life-cycle. They are pretty tough and en masse or in ones, twos and threes they can add a dramatic impact to a border.
At the end of their first year we tend to dig them up carefully (they have a long tap root that can easily snap) and move them to a place in the garden with plenty of space.
The latin name is Verbascum bombyciferum, the common name is Mullein.
Attractive as they are, they can also be devastated by the caterpillar of the Mullein Moth. This is easily recognised by its white, yellow, and black markings:
These are first noticeable when you see holes appearing in the leaves and the caterpillars are vey small. They chomp away at the huge leaves and by the time the plant has matured, so the caterpillars have become big and fat and the lower leaf stumps of the plant are covered in black caterpillar poo. They are so unsightly then that we normally pull or dig these plants out. You could go round picking off the caterpillars or spray them off with a jet of water. We generally have so many plants that we just don’t have time to do this and luckily some plants will escape the massacre.
These caterpillars are harmless to other plants around them, although I understand they they are quite partial to a Buddeja leaf too.
I haven’t found them on these plants yet.