Penstemons

These upright, bushy plants, with narrow pointed leaves, produce spires of thimble-like flowers, sometimes flaring at the tip. Colours include white, pink, red, blue and purple; some flowers combining two colours known as bi-colours.

Penstemons grow in most soils that drain freely, flowering prolifically in fertile soils. They need full sun. In cold areas, they appreciate the protection of growing near a sunny, warm wall.

Wet, heavy soils are unsuitable for penstemons. They will not flower much in shade.

Deadheading plants encourages them to continue flowering. In cold areas, take cuttings in late summer and overwintering these in a cool greenhouse is a good way to safeguard against potential winter losses.