Coronilla valentina subsp. glauca 'Citrina'
Coronilla valentina the subspecies glauca 'Citrina' is not only evergreen but produces numerous bright yellow flowers in winter that have a fantastic perfume.
Coronilla valentina the subspecies glauca including 'Citrina' is an evergreen with a slight blue tinge to the green leaves.
Its big appeal are the numerous yellow deliciously perfumed flowers. Coronilla glauca Citrina has paler lemon yellow flowers over winter and spring whilst Coronilla glauca provides a brighter deeper yellow floral display over the spring and summer period.
Coronilla Winter Hardiness
Plant Post is a specialist plant site that predominantly focuses on evergreen plants for year round colour and greenery so hardiness has to be taken into account.
Most Cultivars of Coronilla valentina have an RHS hardiness rating of H4 so generally hardy down to -10°C. It seems to do best in full sun although I have been experimenting growing it against a north facing wall scrambling through an evergreen Magnolia which it seems to like.
I also grow the variegated Coronilla valentina subsp. Glauca 'Variegata' which is meant to be less hardy although it has taken plenty of frost and temperatures down to -5°C.
Sunshine does seem to encourage it to flower more profusely and raised, dry or well drained soil doesn't seem to cause a problem. I have tried these in pots which I never water so the only water they get are from rainfall and they survive although not as happy as being grown in the ground.
Coronilla being from the mediterranean is suited to dry soil and so is suited to raised ground, pots and rain shadow positions near walls. The oldest and largest one I grow is on a south facing wall on slightly raised ground where no rain reaches the ground. I do have difficulty growing anything there due to the summer heat and lack of rainfall and this plant tolerates the position beautifully.
Coronilla Valentina Subsp Glauca Flowers
All of the flowers for the subspecies glauca are yellow, the difference is that the glaucous scorpion-vetch and glauca Variegata have deep yellow flowers whereas Citrina has lemon yellow flowers. All three have a gorgeous fragrance so growing near a front or back door you can appreciate the perfume.
When Does Coronilla Flower?
By my experience this doesn't seem to be a plant that keeps to strict flowering schedules. In 2017 with a mild winter all of the Coronilla glauca I grow started flowering in late February to Early March time.
Flowering has occurred in September although as a rule they do not seem to produce any flowers in autumn.
How Big Does Coronilla Grow?
There is some variation in the different cultivars but generally it doesn't tend to grow much larger than a metre tall and about a metre diameter, generally less. It is more of a bushy shrub and benefits from being trimmed back from time to time as it can get quite woody.
Whilst Coronilla glauca is not a climber it does prefer to be grown against a wall especially if it is south facing so it catches some direct sun.
I have found it can sometimes need support so can be trained against a wall or staked to give the base some aid against strong winds and soggy ground. In winter if the ground gets saturated and softens the stem can rock especially in strong winds.
This is also a useful plant to grow amongst others, particularly the variegated sport Coronilla valentina subsp. glauca 'Variegata' which tend to be less hardier. This shelter affords some protection being grown amongst other plants which also offer growing support. The white cream and blue grey green leaves also stand out surrounded by deeper green foliage.
Coronilla Attracts Bees
Just like some other shrubs that hail from the mediterranean such as Rosmarinus officinalis, the early flowering Coronilla which incidentally starts flowering about the same time as Rosemary in the UK, is Bee friendly.
Around March and April time when they are in full bloom the garden has a constant stream of Bee visitors that are attracted to this source of pollen and nectar. It is well worth growing the yellow flowering Coronilla as well as the lilac flowering Rosemary just for the fact they are a valuable early food source for Bees in the UK.
List of cultivars
Coronilla valentina subsp. glauca glaucous scorpion-vetch
Coronilla valentina subsp. glauca 'Citrina' bastard senna 'Citrina'
Coronilla valentina subsp. valentina
Coronilla valentina 'Sulphurea'
Coronilla valentina 'Cotswold Cream'
Coronilla valentina subsp. glauca 'Variegata'
Coronilla valentina subsp. glauca 'Pygmaea'
Coronilla valentina 'Variegata'
Coronilla valentina 'Clotted Cream'
Coronilla valentina subsp. glauca 'Brockhill Blue'
Coronilla valentina bastard senna
Coronilla valentina 'Creamed Corn'
Coronilla valentina 'Lauren Stevenson'
Coronilla valentina 'XXS'
Coronilla valentina subsp. glauca Large Leaved 'Citrina'