Culture
Best grown in organically rich, consistently moist, well-drained soils in part shade. Tolerates close to full shade. Plants prefer cool summer climates where they tolerate full sun conditions, but they appreciate significant afternoon shade in the heat and humidity of a typical St. Louis summer. Plants do have somewhat better tolerance for summer heat than some other species of primula. Plants often perform best with a spring-summer mulch that helps maintain soil moisture and keeps roots cool. Plants thrive in placements along streams or ponds and tolerate some wet soils. Plant foliage may depreciate in the heat of the summer. Propagate by division in spring after bloom.
Noteworthy Characteristics
Primula vulgaris, commonly called primrose, is a semi-evergreen, rosette-forming perennial that is native from southern Europe to western Asia. Short-stalked, often fragrant, salverform, pale yellow flowers (each to 1" across) bloom in clusters rising to 6" tall from the center of an open basal rosette of wrinkled obovate leaves with pubescent undersides. Leaves elongate after flowering to 6-8" long.
The genus name Primula means "little earliest one" and is the feminine diminutive of the Latin primus.
Specific epithet means common.
'Kerbelcob' features deep blue, 1.25" diameter, double flowers held above clumps of dense, uniform foliage. Plants will reach up to 8" tall and 12" wide at maturity. This plant is protected by patent number PP16397.
Problems
Slugs, snails, aphids and red spider mites are sometimes seen. Botritis, gray mold, root rot, rust, powdery mildew and leaf spots may occur. Susceptible to several viruses.
Uses
Bright spring flowers that grow well in part shade locations including border fronts, rock gardens, open woodland gardens, under trees, along paths, along streams/ponds or in boggy areas. May be an effective edger. Also may be grown in pots.