|1||15C+||Indoor||Grow as a houseplant or under heated glass.|
|2||10 to 15C+||Indoor / Outdoor||Grow indoors, or outdoors in summer in a sheltered spot|
|3||5 to 10C||Tender||Grow outdoors in summer, and in a heated glasshouse in winter.|
|4||1 to 5C||Tender||Grow outdoors or under glass without risk of frost.|
|5||-5 to 1C||Half-Hardy||Hardy in coastal/mild/sheltered areas. Will not tolerate hard/sudden frost. May require winter protection in situ. such as fleece or straw mulch.|
|6||-10 to -5C||Hardy||May suffer at altitude, central/northerly locations, harsh winters, cold gardens and when grown in pots.|
|7||-15 to -10C+||Hardy||Will survive most severe winters but may be at risk in central/northerly locations and in pots. Top growth may be destroyed but will usually re-grow.|
|8||-20 to -15C||Hardy||Will survive severe winter, but may need protection when grown in pots.|
|9||-20C & Colder||Very Hardy / Hardy||in the severest European climates.|
Out of stock
Deciduous clump-forming perennial with strongly toothed heart-shaped leaves and tall, dense racemes of small deep yellow flowers on contrasting black stems.
Grow in deep, fertile, reliably moist soil in full sun but with some shelter from midday sun. Protect from strong drying winds.
Height and spread after 1 – 2 years 1.5cm x 50cm
Mature height and spread after 3 – 4 years 1.8mm x 1m