Phlomoides tuberosa aka Tuberous Jerusalem Sage

Phlomoides tuberosa is a perennial in the mint family. Sources also list it under the name Phlomis tuberosa. Common names include sage-leaf mullein and Jerusalem sage. Its native range spans parts of Europe and temperate Asia. This range reaches east through Siberia, Mongolia, and China. It is not native to Britain or Ireland. Wild plants grow on dry, rocky ground among other herbs. They also occur in wet grasslands and valleys in northern China.

The plant forms a clump above roots with tubers. Garden plants stand about 3–5 feet (0.9–1.5 m) tall. Their spread reaches about 2 feet (0.61 m). The basal leaves form a lower mound of green growth. This mound can reach about 1.25 feet (0.38 m) high. Each leaf has an arrow shape and a rough surface. Deep veins and sharp teeth give the leaves clear texture. The foliage dies back rather than staying green all year. Tall, leafy flower stems rise above the basal mound. These stems have four angles and dark red to purple tones.

Small, tube-shaped flowers grow in dense rings along the stems. A stem can carry as many as eight flower clusters. Flower colours range from pink to lavender and purple. Reports place bloom from May into August, depending on location. Seed heads follow the flowers during summer. They keep their shape through autumn and into winter. The flowers and lasting heads give borders height and structure. Gardens also use this plant in meadows and gravel beds. Missouri Botanical Garden lists birds and butterflies among its visitors.

Grow it in fertile soil that drains well. Full sun suits it best, though it tolerates some shade. Sandy loam works well, and added organic matter suits cultivation. It accepts acid, neutral, and alkaline soils. Moderate soil moisture supports growth, but plants can withstand drought. Avoid wet soil when choosing a garden site. Chicago Botanic Garden gives USDA zones 6–9. The RHS rates its UK hardiness as H5. Divide plants in spring, or sow seed that season.

Serious pest and disease problems are not widely reported. Leafhoppers may still attack the plant. Plants For A Future lists the cooked root as edible. It contains starch but has a somewhat bitter taste. That source reports no known hazards or medicinal uses. This does not establish safety for pets or every use.