Hypericum kalmianum 'Smhkbf' COBALT-N-GOLD (Blues Festival®) St. John's Wort
size/type
medium-sized shrub,small shrub
usual height
0,6-0,8m
usual width
0,8-1,3m
leaves
deciduous broadleaf
colour of leaves
flowers
showy
colour of flowers
blooming time
July-September
location
full to partial sun
soil type
any (acidic to alkaline)
soil moisture requirements
evenly moist but well-drained
USDA zone (lowest)
4 (down to -34°C)
winter protection
for zone 5+6
for zone 7
categorized
St. John’s Wort is a well know perennial from our meadows and fields. However, there are also a few woody species popular for their shrubby habit and extended flowering period in summer. Kalm’s St. John’s wort is one of them and COBALT-N-GOLD is a variety from 2009, bred by Timothy D. Wood from Grand Haven in Michigan, USA, the same man behind the previous variety SUNNY BOULEVARD®. It was granted a US patent No. 25795 in 2015.
Description of the plant:
COBALT-N-GOLD is a low, dense growing variety of St. John’s Wort with erect stems and rosemary-like leaves. Each stem bears cymes composed of saucer-shaped, 3-4 cm across, golden yellow flowers with profusion of stamens in the centre. Its starts blooming in July and continues until early autumn which makes it one of the most attractive and longest flowering shrubs of late summer. Compared to SUNNY BOULEVARD® this variety bears glaucous foliage which is still narrow, yet a little a wider. COBALT-N-GOLD makes compact, densely branched, mounding shrubs perfect for informal hedges along pathways or companion plants for multi-stemmed, taller growing shrubs as an understory. It can take a little bit of shade but performs best in full sun.
Prune it in early spring – cut last year’s growths by 30-80% - the harder you prune the better-looking shrub you gain. Grow these smaller hypericums in full sun, moderately fertile soil that is very well drained. It is absolutely pest-free and disease resistant. Fully hardy to about -34 °C (USDA zone 4) and suitable for year-round cultivation in outdoor pots with good drainage and without saucers.
Last update 02-10-2022
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